%if 0 ; docs{ A BOOTABLE FORTH STYLE "OS" This file represents a bootable readonly forth-like system. It uses a byte-code approach to creating a simple forth dictionary. Its overall aim is to create a portable and minimal booting interactive system. All commands entered interactively (in the SHELL loop) are 'compiled' into bytecode either into an anonymous code buffer or to the dictionary and then executed. Also, the general aim of the code is to get to a source interpreter and compiler in the minimum code size possible. This is by no means a standard forth! It is an experiment. MOTIVATION "our civilization will collapse under the weight of its own complexity" charles moore. "simplicity is more fertile than complexity" anon This code is an attempt to answer a question: "what is the smallest bootable, interactive, portable system that can add to itself from source code, in a structured, orderly and understandable way?" To elaborate... "Smallest" The aim of any developer should be to reduce the size and complexity of the core system (not increase it) while satisfying the conditions below. Currently (2018) about 7K core system. "Portable" from microcontroller to mainframe using a rigorous practical virtual machine and bytecodes. "interactive": actually this condition is not so important because a system that can add to itself from source code can easily compile and execute an interactive REPL interpreter or shell. But it is important that the user can choose what bits to add to the system, and what not to add. "Add to itself" via disk, serial connection, or tcp, using globally unique and locatable object names (words). So each word has a domain name which, when combined with the word itself, forms a globallly unique name. "from source code" This condition implies that a compiler must be present "Bootable" doesnt require any operating system on any architecture. "Structured" must add to itself in manageable, contained units of code that can be debugged individually. "Understandable" must strive to be simple enough for an average coder to understand after reading for a few days. Actually forth contains partial but powerful solutions to some of these criteria. The question above is important because it has implications for our consumption of resources, impact on the environment, beholden-ness to obsolescence and relationship with technology. In particular power consumption is related to software complexity. Simple software can run on small low-power consumption computers (such as a coin-cell powered bicycle computer). Another important aspect is digital security and the "knowability" of code. Opaque massive compiled code is inherently insecure because it is unknown and unknowable. At some point governments will need to acknowledge this, because the trojan horses they implant in various systems will be compromised by the trojan horses that others place in their systems. It is a futile arms race of insecurity. This question also has implications for how human beings interact with technology and whether they are in control of those interactions or are victims of them. The divide between "programmer" and "user" is artificial and serves commercial purposes not human ones. Just as the divide between operating system and software is also artificial. To expand a little, the code uses bytecode and a simple 2 stack virtual machine to hopefully allow portability between microcontrollers and modern laptops/desktops. By attempting to port to very disparate chip architectures (avr micros, x86, z80, arm), the designer is encouraged to think about what is essential for usability and what is just fluff. This may seem to contradict one of charles moore's principles which is "dont code for what you may need in the future, dont try to generalise your code". But it is more an attempt to harness the power of the commonality of the internet and the power of virtual machines to cheat obsolescence. Tinyness and minimalism will hopefully not be sacrificed. The system tries to make the core as tiny as possible while not sacrificing "understandability". So the aim is to get to a source code compiler in the minimum amount of code. Forth ideas facilitate this. Another important idea is that of universal naming. All objects (in this case forth words) should have a resolvable, locatable, unambiguous universal name eg 4th.core.dup Since almost all code is source, then each object (forth word) consists of a minimal syntax (space delimited words) and a series of named-objects (other forth words). This has the simple but powerful consequence that, given the name of a word, all "dependencies" can can be located and obtained, and the given word can be compiled and run. This also applies to data structures. On top of this system we could code a parsing machine see bumble.sf.net/books/gh/gh.c (nearly but incomplete) which would allow the forth machine to recognise and assemble more expressive syntaxes for code and data structures. JOURNEY copying machine code or peeks and pokes into a vic20 (?) qbasic as a teenager. Nice help screens on an IBM XT? First had to learn x86 assembly which I had been meaning to do since the age of 12. Learn about x86 bios calls. Then had to think about forth for a number of years. First heard of forth from D. McBain. Then had to think about parsing and compiling etc. Coding php scripts, in Wagga Wagga NSW. html-form code editor in php, writing text converters in #!/usr/bin/sed and thinking about the sed "virtual machine" in Almetlla de Mar, Catalunya. learning [TCL] and its simple bracket syntax (almost as simple as forth). Learning a little Java in Bogota, but never achieving anything useful. Linux shell scripting and bash. c coding. Writing the pattern parser unsuccessfully in many languages. Some avr assembly. Markdown and code that produces code. Learning x86 assembly booting from MikeOs template. FEATURES Case sensitive, and all core words are lower case, but in documentation I may make them upper case so that it is obvious that I am referring to the forth WORD and not the English word. Unlike some forths, this version compiles commands entered interactively to an anonymous buffer. The advantage of this is that flow control words like if, fi, else, begin, until... can be used interactively, not just in colon : definitions. Bytecode. Not a standard forth: eg, THEN is FI "execute" is "pcall" to match with "fcall" opcode Even "proceedures" (everything after the no-op procedure) are written in pseudo forth. That means that they are just a series of calls - to opcodes and other proceedures. The idea is to make porting to another architecture simpler. DIFFERENCES FROM (94?) STANDARD FORTH I have attempted to keep the idea of a "compiling" forth. This means that there is really no such thing as "interpreting" in this forth. The only interpreting opcode is PCALL and I may remove it. My motivation for this is to stick as closely to the operation of real machines. Chips general can only execute machine code that exists at some location in memory. I want to adhere to this principle to make the idea of a "virtual machine" more coherent. * All defining words will probably have to be immediate. * All standard words are lower case. postpone is post RECURSE is just the name of the word. For example : gcd ( a b -- gcd) ?dup if tuck mod gcd fi ; just works and finds the greatest common divisor. This may have the implication that two words cannot have the same name (which is also required by unique naming ideas and namespaces) IF/THEN is IF/FI because I find THEN just too different to every other computer language ever invented. EXECUTE is PCALL WORD is WPARSE because the word word is used for way too many things in Forth. eg function in dictionary, 2 bytes of data, space delimited text ...Also wparse works for various whitespace characters (tab, newline, space ) not just the space (asci 32) character. VARIABLE is VAR because I dont need to type any more than I already do. IMMEDIATE is IMM COMPILE, is ITEM, and works slightly differently from COMPILE, (it takes a flag that indicates if the argument is an opcode, literal or procedure) But that may change. I is ii J is jj CHAR is an immediate word. To use CHAR in a colon definition, do "char * literal" or just use [char] accept does not take a character limit, yet. COMPARE is ( a A n -- flag ) rather than ( a n A N -- a' ) so this compare assumes that the 2 strings are of equal length. STATUS The system is edging towards a usable forth-style system. It can read and write to usb from an x86 system in real mode, but there is no easy way to edit buffers yet (apart from 'accept') so is probably not usable as a standalone system yet. PROBLEMS defining words do not update the dictionary code pointer but 'does>' does, so we can use does at the end of a defining word to make sure the code pointer is updated PERFORMANCE A virtual machine is normally considered to run slower than native machine code, but some optimisation techiques are possible. We can replace x86 'calls' to opcodes with jumps and we can keep the top of the stack in ax. Also it should not be too difficult to compile bytecode to native machine code, if necessary. * 16 june 2018 performance testing: With exec.x using calls to opcodes and pop/push return pointer in the opcodes, performance is as follows using the word 'timeloop' to measure looping speed With qemu on asus e402m machine 500 000 loops took 495 milliseconds 1000 000 loops took 935 milliseconds Booting from usb 1 million loops took 110 ms 2 million loops took 220 ms 10 million loops took 1100 ms So as expected, much faster on the actually machine rather than in qemu. But is this fast enough to play chess? * 17 june 2018 On Ibm thinkpad r52, using exec/call version, real mode using word 'timeloop'. booting from usb. Strangely this seems twice as fast as when I converted to using jmps and having top of stack held in dx. 1 million loops took 55 milliseconds 10 million loops took 275 ms 40 million loops took 1155 ms So surprisingly the old r52 thinkpad was 4 times faster than the more modern asus machine in real mode. * 18 june 2018 system converted from call/ret (in exec.x) to jmp ... With qemu on asus e402m machine. Using word 'timeloop' 500 000 loops took 275 milliseconds 1000 000 loops took 605 milliseconds So by converting from call/ret to jmp there is about a 30% improvement in qemu. On asus eeepc (seashell), using jmp in exec/opcode, real mode booting from usb. 1 million loops took 55 milliseconds 10 million loops took 605 ms 16 million loops took 1045 ms asus e402m machine Booting from usb, jmp (not call/ret) 10 million loops took 990 ms So not much improvement on modern machine. Perhaps modern chips do realmode very badly. With qemu on asus e402m machine, jmps and top of stack in DX real mode. 1 million loops took 385 milliseconds 2 million loops took 825 milliseconds So there seems to be a significant improvement with top of stack in DX. VIRTUAL MACHINE AND OPCODES This forth system tries to emphasize portability, knowability and interoperability. The idea is that each opcode should be standard and have a defined semantic operation on the machine. Also, periferals are considered part of the machine. But periferals (sensors, actuator, transducers etc) are myriad and pluggable and unpluggable. So how do we handle this situation: The answer is that the set of available opcodes defines the machine- actually forms the machines "signature". Since possible periferals and devices attached to the core 2-stack machine are infinite, we need at least 2 bytes to describe them. Or a utf8 type of variable length encoding. So: "1234567" may be the opcode to read a 3 axis accelerometer. The number 1234567 must be unique, universal and defined in some public document. But in the actual machine this opcode will be probably mapped to a much smaller number (say 66) so that it can be encoded in one byte or less (depending on how many periferals/sensors the actual machine has). So the signature of the stack machine includes all standard opcodes expressed as a list of ranges 1-4, 7-9, 11, 13 etc as well as any mappings eg 1-4,7,9,66:1234567 Also there are further subtleties here, which need attention. Eg: Absent opcodes can be "emulated" or in some cases just keyed to NOP. For example an opcode which moves a robotic arm could be emulated as a video monitor display of the robotic arm moving. An opcode which sets the text colour for a monitor may not be essential for the operation of the software and may just be keyed to NOP. It would be nice to be able to create missing opcodes using "high level" forth (source code) as well as assembler appropriate to the current chip architecture. Some opcodes, even if absent, can always be constructed from core stack machine operations. For example double precision arithmetic (eg D+ D- ) can be constructed from 16 bit forth opcodes (+ - dup swap etc). But if speed and efficiency is important for the given application, then these operations should be coded as opcodes written in assembler. The general aim is for the structure of the target machine to be knowable and analysable from within code. STRUCTURE OF THE DICTIONARY One of the key ideas of a forth-like system is the use of a linked list with each item in the list being a data structure with the name and code for a particular function. This linked list is called the dictionary. The current code uses the following structure for the dictionary: [link to previous word] 2 bytes [name of word] [count of name] 1 byte || IMMEDIATE FLAG [code] [data or "parameters"] ... next word structure This uses "reverse" name counts. So the byte containing the length of the name is after the name, not before as in the majority of forths. This allows us to decompile byte code by getting a list of pointers to code and then looking up the name. But it may have other unknown disadvantages. eg db 'minus', 5 dw exec ; link to previous Another refinement is to hold the top element of the stack in ax, which simplifies a lot of stack manipulation. eg 1+ becomes "inc ax" etc. OBJECT ORIENTATION The code below may contain a hint as to how to emulated object orientation with forth. Each of the function pointers could be like a method on an object. create buttons ' ring , ' open , ' laugh , ' cry , : button ( nth --) 0 max 3 min cells buttons + @ execute ; IDIOMS This section contains recipes for doing simple or common programming tasks with this forth * use a counter to print something once every 8 loops ------- var nn : ++ dup @ 1+ swap ! ; : something ; initialise counter to 0 0 nn ! begin ; print 8 words to a line nn ++ nn 8 mod 0 = if cr fi again ; ,,, CULTURE Forth has its own culture. It uses a set of words and concepts which are completely different from the main stream coding world. It has a set of naming conventions which are not related to normal coding naming conventions. These days forth is a forgotten backwater with little or no mainstream relevance apart from embedded systems, but its ideas remain powerful. NAMING Since Forth words can contain any punctuation, these little characters are (over?) used extensively to try to convey the meaning and purpose of words. Below are some notes about traditional ways that this has been done TOS top of stack, displayed as rightmost element. NOS next element on stack. / divide by something eg 2/ divide by 2 / word divider eg: r/w "read/write" s/o "search order" / search for something (convention from unix) eg ss/ search for words in source code blocks . display something (print to screen and remove from stack) , compile something (store executable code or data in memory) : define a new word or data buffer @ fetch something from memory (and push to data stack) ! store something in memory. ' get the execution address of something. ' modify something (in stack comments) eg x' "x modified" c character operation eg: c@ fetch one character (8 bits) (something) is the runtime behaviour of "something" [something] is an immediate version of the word "something" That means that it executes "immediately" or at compile-time. XT means "execution token" which is just the address of code that can be run by the virtual machine. (either byte code or machine-code). INSPIRATION The code was original inspired by the helpful and simple instructions from MikeOS on how to get a minimal booting x86 "operating system" working. The code was also inspired by the incredible simplicity of forth-like systems, and also, the ease of implementing a bytecode system using indirect jumps. In general, simplicity appears to be much more fertile than complexity. Linus Torvalds was inspired by the simplicity of Tannenbaum's minix system to start the Linux journey. Tannenbaum may have been inspired by the simplicity of early unix systems. Donald Knuths "literate programming" where the source code includes the documentation and also self-documents. The idea is that the source code is a document which describes itself, both at compile-time and at run-time IMMEDIATE WORDS One of the main semantic problems of forth systems is the idea of immediate vs non-immediate words and "run-time" versus "compile-time". Immediate words execute at compile-time and non-immediate words execute at run-time. These ideas occur because forth is a compiling system. eg char " puts the character " (integer 34) on the stack at run-time but [char] " or [ char ] " does the same thing at compile time, no not correct... FORTH BOOKS "An invitation to forth" ... "Threaded Interpretive Languages" by RG Loeliger Apparently some info on how to build a forth system. "A Complete Forth" (1983) A good general overview of early forth "Thinking Forth": Brodie An introduction to forth. Available free online. "Forth Programming Handbook" 3rd Edition, Conklin, Rather (2007) A good reference and explainer for the 1994 standard language. Also reasonable recent. "Forth: The next step" by Ron Geere This is a simple and useful book which defines some handy new words in forth (such as squareroot etc). "Forth Application", S.D.Roberts Strange and unreadable, at least to me. But no doubt with some good ideas. Scientific Forth: Julian V. Noble A vey well regarded forth book but out of print. Finite State Machines in Forth, an article by J.V.Noble http://galileo.phys.virginia.edu/classes/551.jvn.fall01/fsm.html Good articles by Noble http://galileo.phys.virginia.edu/classes/551.jvn.fall01/primer.htm http://galileo.phys.virginia.edu/classes/551.jvn.fall01/primer.htm Realtime forth PEOPLE Anton Ertl Mitch Bradley FORTH SYSTEMS This is a cursory overview of various active and historical forth systems. Dr dobbs: the commando forth compiler GFOS A booting forth system for x86, some sound and image support. HDE ide https://el-tramo.be/blog/waforth spf.sf.net Figforth, forth 79 standard, forth 94 standard LMI-Forth for the IBM pc MVP-Forth not sure where it ran Open Firmware (Mitch Bradley) Still used at OLPC for booting laptops. A major project. cforth based on mitch bradley olpc forth gforth a big complete forth written in c. (non-booting) amforth for avr chips flashforth for microcontrollers, eg avr (arduino) using flash memory. Runs on Harvard architecture microcontrollers and uses a "memory map" technique to separate data memory from program memory. Multos - stack based vm os Colour vision systems, bacchus marsh, victoria, au Keycorp, chatswood, KYC www.keycorp.net www.forthos.org http://www.vsta.org/contact/andy.html A bootable x86 forth in protected mode with oo extension Example of forthos oo syntax Set -> new constant mySet 1 mySet -> add 123 mySet -> add * Add a method to a class Set -> :method addRange ( high low self -- ) -rot do i over -> add loop drop method; GOTCHAS * There is no way to list all wordlists, unless we maintain a list and add to it every time a vocab is created. * In old forths u* and u/ leave a double precision result. so u/ is "um/mod" and u* is "um*" I think. So that code needs to be translated. * If one of the word counts in bytecode is wrong you get an error: "emit ?? @last " SOLVED BUGS * I think having a signed c@ etc is a bug. We need an extend sign opcode for relative byte jumps but not automatic signing of c@ * u. stopped working because I changed /mod to be a signed division. Change u. to use u/mod instead * mod /mod and / did not work for negative numbers !!! Needed to use a signed division instruction in x86 * ifnot was broken (feb2019) by the new version of if (long jumps) BUGS * The old >code here problem arises with the def below : Defer create reset [op:] exit 0 , 0 c, ; imm If we do "defer t1 defer t2" then t2 is compiled right after the count field of t1 ! I dont think the "does>" trick will work here. But adding a "code>here" cludge does work. Eg : Defer create reset [op:] exit 0 , 0 c, code>here ; imm The problem can be seen by using the first "Defer" (with no "code>here") and inspecting >code For example: Defer t1 >code @ * The following definition is causing a spectacular meltdown. The "3 allot" is causing the problem, but I dont know why. : Defer create [op:] exit 3 allot ; imm * nop should be "noop" to be more standardish * circle and fcircle have a zero bug at the moment. * "deci 256 hex U." prints 256. This is because the interpreter convert the string 256 to a number at compile time which is before "hex" has executed... Then a litw is compiled but it is not affected by hex. So we could make hex immediate? Or have a "state smart" hex? Could we have 3 states immediate/normal/defining. In defining state something is actually being added to the dictionary, in normal mode things are being compiled but not anything permanent to the dictionary. This is an added complication... * "pad char z" actually puts asci code for 'z' on the stack before pad! This is because "char z" is getting executed immediately and "pad" isnt. One solution might be to make "char" the same definition as [char] but then how do we do [ char z ] ??? All this arises because I try to compile even interactive commands... * use EOL instead of 13/10 numbers etc. This is more portable * Also either 2* or /2 should be the other way round * semicolons with no preceding : def will crash the system. Eg nop ; * The code below causes problems. It executes correctly, header is created and the data "abc" is written to the dictionary, but the ">code" variable is not updated properly [ create test char a c, char b c, char c c, ] We can fix the problem with: [ create how char a c, char b c, char z c, code>here ] or with [ create how char a c, char b c, char z c, sync ] But or some reason, if I put sync, or code>here in c, then the system crashes. * need to do [ create table 1 , 2 , 3 , 4 , ] in the interactive interpreter to make a list of values * thinking about words like [op'] [op:] call: can be difficult. The best idea is to use them in a word and see how they compile with "see". * doing "post >r .s" in the interactive interpreter crashes the system. * If you write -1 instead of 1- there will be no error but the word will not do what you want. 1- is an opcode the decrements the top stack item. -1 pushes -1 onto the stack. This is an easy mistake to make. * do/loop still has the +/-128 byte limit which is a great handicap! * doing do/loop in the interpreter is crashing with showglyph and "ms" etc. but seems to work in source code * running on asus e402M the cursor flashes even when I try to hide it. Need to set bit 5 ? Also, green cursor leaving green lines on screen. * watch for any defining word that is not immediate! eg var, con, 2con etc. * watch for nested comments ( ( ... ) ) ! * see the xyset: code to see how to create a data array in this dodgy and buggy forth (need a superfluous "does>") * to define a new word in a source block, eg "xyset: test" we have to put that phrase after all other definitions in the block, otherwise it causes and error. This comes back to the old dictionary/anon switch bug. * [ create data 0 , 1 , 2 , ] this works in the interactive interpreter but not in a source block. In source we have to do : data [ 0 , 1 , 2 , ] ; which is odd. Also, in standard forth you dont need [...] around the words. * When a defining word uses create but is not immediate then it crashes the whole system, which seems a little overly dramatic. * "see" doesnt display defined words very well. This is because see cant, at the moment, display data fields (strings etc) within words. * how to return the parameter (data field) for a defined word? * c@ and c@+ convert bytes to signed words, but do we really need signed bytes? * ss/ only prints one match per block * Extra semi-colons give strange errors, like ": ?? within" even though the extra semi-colon was well before the "within" word. * the "ss/" is missing some searches because it seems to add a space at the end of the search word. * "thru" or one of its words is eating 1 stack item. * when running on x86, not qemu, some video modes dont clear text on the screen after backspace space characters are emitted. * "ii" doesnt work within a loop if there is anything extra on the return stack (put there with ">r" for example within the loop). This may just be a feature of forth since there is no way for ii to know what is on the return stack * ./ not working interactively well. That is : ./ 10 parse drop drop ; imm : ./ 10 parse type ; imm truncates one character. This is because the input buffer has no newline ending (just a counted string). And when "parse" doesnt find a character it is truncating one character. One work-around is to put an extra space at the end of the line. Changed the behaviour of parse so that it returns the rest of the input stream when it doesnt find the character. * All words such as "if", "until" etc need to be rewritten in source compiling an jumpz..ljump sequence if the target is further away than +/- 128 bytes. "again" has already been rewritten and removed from bytecode. The new compilation techniques can easily be tested by writing small words using each control word and seeing how the word is compiled. TO DO (june 2018): immediate tasks: * asci animals. using "line" and "rot45" etc words. * make namespaces using interleaved linked lists * list words with their fully qualified name. * fix create bug for defining words by writing (create) and create as an immediate word, and adding code to semicolon to see if def bit is set and compiling semicolon code there. So we check the def bit and either do FCALL (;) or LIT, FCALL C, LITW, (;), , etc depending on whether def is set. Bug has been fixed for does> and (does>) * allow simple editing of blocks to test writing blocks * change 'decomp' so that it displays the address as well as the name of the fcall functions. * use wsize in see see, etc to decompile whole word. * write DEPS ( xt -- ) create a list of xts which are dependencies of word represented by xt. * write a 'dependency' compiler. Find a word on disk, leave its block number + offset and then find all sub-words and leave their block numbers + offset on the stack or in some kind of buffer. Check that no duplicates are added. This is tricky, we need offsets and lengths of each word in the block or file, otherwise we need 1 file per word. A dependency compiler needs a set type and an add word is there any reason to loop on the return stack as opposed to the data stack. It would be more convenient for rloop.x to decrement the top data stack item!!! * a "search bit" in the name count field (next to the immediate bit, perhaps. This makes the word invisible in the dictionary)... not sure if necessary. * make READ do a number of attempts to read disk blocks (1K) * rewrite some words as "source" now that the : compiler more or less works. * find out what words are really necessary for the : word * it would be good to be able to add new "opcodes" dynamically to allow for the situation where new hardware becomes or is available. For example, if a gyroscope is available, then extended opcodes should read data from it. Yes the machine should be able to build apon itself/ add new opcodes to itself. * make a "document" dictionary, or shadow comments to other diskblocks * "dictionary full" check, ie. is there any more memory in which to place new words? 'unused' word or 'free' * stack underflow check? * implement block and buffer. Buffer writes to disk and frees a buffer and block reads from disk. block calls buffer * all defining words need to be immediate, so 'does>' could just do that automatically. see mike gonta: "all you wanted to know about usb booting but were afraid to ask" for important disk geometry info, fat12 info and read/write usb memory. complete source example MEMORY MAP The way that the code and data is laid out in memory is important. The bootloading segment (512 bytes) loads more code into memory (a few K) and then jumps to the entry point. When the code dictionary grows (by the use of new colon : definitions) the new dictionary entries should be placed in memory after the end of the dictionary. CHALLENGES How to write new code words back to disk? We can either write compiled code to disk as part of the dictionary, or just write source code to disk in forth-style "blocks". This is potentially dangerous, if we accidentally write to the computer hard disk we may corrupt the file system or even the operating system! Some kind of fat12 file system would be convenient, so that I could edit source code on some other operating system. Or at least copy it. Harvard architecture is not going to be easy. HOW TO BUILD AND RUN THIS CODE We can either run the code in a virtual machine like qemu or else actually write it to a usb or cd and boot it! The simulator is good for testing, but the usb or cd boot shows you how it works on real hardware! tools: nasm, qemu, dd, bash shell (or any other shell for compiling etc) linux (makes things easier), sed, date, vim, asciidoctor, enscript - for formatting and printing source code * create a printable pdf of the code in 2 columns landscape format enscript -o - -2r -f Courier7 os.asm | ps2pdf - os.pdf * compile with nasm into a bootable executable nasm -fbin -o os.bin os.asm; * make a 1.4Meg floppy image and insert the executable into it. sudo rm os.flp; sudo mkdosfs -C os.flp 1440; sudo dd status=noxfer conv=notrunc if=os.bin of=os.flp' * run the executable floppy image with qemu simulator (VM) sudo qemu-system-i386 -fda os.flp' To "burn" to usb or cd try: * use dmesg to see what your usb flash drive is called * unmount the usb flash drive umount /dev/sdc * write the bootable floppy image to flash drive: WARNING! sudo dd if=os.flp of=/dev/sdc !! The code above deletes all other files on the memory stick Be very very careful that you dont do this to your hard-disk or you will end up with an unbootable computer. !! The light should flash on the usb stick indicating that data is being written. Then just reboot the computer and choose the boot device. I think I had to "enable csm" or "choose floppy" mode in my bios to get the usb stick to boot. Some bash aliases for compiling and running the code. # make qemu open maximised but not full screen alias os='sudo qemu-system-i386 -fda os.flp & sleep 1; wmctrl -r QEMU -b add,maximized_vert,maximized_horz' Below is a bash function which includes preprocessing of forth source code in %if 0; %endif; blocks. The preprocessing code is in os.sed. This is convenient because NASM doesnt seem to have any kind of multiline DB or DW syntax which means for defining forth source code in a nasm file we have to put "db ' " around every line. The sed line deletes the marker lines (lines ending in "code{" and "}code" ) as well as comment and empty lines and put the "db '" syntax around each line of text. # run the forth os os() { if [ -z "$1" ]; then name="os" else name=$1; fi echo " running ${name}.flp " # get rid of other qemu windows for clarity sudo pkill qemu sudo qemu-system-i386 -fda ${name}.flp & sleep 1; wmctrl -r QEMU -b add,maximized_vert,maximized_horz } # compile the forth style byte code system with some sed preprocessing # of the nasm file (to allow multiline text source code) ccos() { if [ -z "$1" ]; then name="os" else name=$1; fi echo "now compiling ${name}.asm " echo $(date +%d%b%Y-%I%P) sed -f os.sed ${name}.asm > ${name}.pre.asm # The line below adds the time and date to the machine name sed -i "/\.sig-machine\.name/s/' *$/.$(date +%d%b%Y-%I%P)'/" ${name}.pre.asm nasm -fbin -o ${name}.bin ${name}.pre.asm; sudo rm ${name}.flp; sudo mkdosfs -C ${name}.flp 1440; sudo dd status=noxfer conv=notrunc if=${name}.bin of=${name}.flp } cos() { cat os.asm | sed -f os.sed > os.pre.asm nasm -fbin -o os.bin os.pre.asm; sudo rm os.flp; sudo mkdosfs -C os.flp 1440; sudo dd status=noxfer conv=notrunc if=os.bin of=os.flp } # compile and run the forth system. alias oss="cos;os" * The sed script used to preprocess the nasm source file #!/bin/sed /code{ *$/,/}code *$/ { # ignore lines starting with "times" in code blocks # 't' jumps to end of script. s/^ *times/times/;t; /^ *$/d; /^ *;/d; /code{/d; /}code/d; # need to 'escape' double quotes s/"/",'"',"/g; s/^ */db " /; # put newline on the end of each line #s/ *$/ "/ #dos line endings #s/ *$/ ",13,10/ # unix new lines are better s/ *$/ ",10/ } HISTORY 21 feb 2019 Ideas: To implement D+ well, we need "add with carry" and "add with overflow" etc like all machines actually have. But we can just implement it by using the FLAGS opcode and examining the individual ov/ca flags. But implementing "flags" on the machine is tricky, because every opcode needs to update the flags properly. Recoded "defer/is" to actually compile an opcode/fcall into the buffer. This allows opcodes to work with defer, which is handy. So we can do: Defer steep ' swap is steep wrote a "reset" word which sets >code and here to point just after the wordname count field. So colon can be defined like " : : create reset ; imm " Although that is a circular definition. Or try this... [ create : ] create reset ; I found this necessary while trying to write a Defer word which is just a buffer to contain code... 20 feb 2019 Realised that dont need "zerolink" word, because create gets the backlink from last/latest. When a vocab is empty it will have a zero backlink anyway. We will just make latest do "current @". And when create sets last, we will set current instead. So current will have to go into bytecode, and it will point to a "dummy" vocab (the core words) until we define real vocabs in source code. 19 feb 2019 Another interesting word would display the search order of wordlists and the name of the last word in each. Trying to respect the forth standards and traditions more by renaming my non-standard words to something different but similar to the Ans forth word. Made alot of progress implementing standardish wordlists. Eg: words.. order, also, defs, context, current, vocab etc Now I need to change the way find gets its search start. Another idea, just use blank lines in blocks to index end/start of words. Can still use an indexing word like ## , maybe at the end of the block. If at end, then have a reverse count (length) at end of block moving away from the idea of having a "wordlist" wordlist. That is a list of wordlists. So, all the "vocabs" such as forth, editor, assembler are words in the core dictionary. But this means there is no simple way to display all existing wordlists. 18 feb 2019 Renamed l.addu etc to li/addu which seems more forthish, but wordlists may obviate such things. Started to write a set of words to implement wordlists (which I like to call namespaces or vocabularies ). Copied useful words vector and cvector from the Ron Geere book. Dont know if they will work. Good test for interactive and block compiling. Seem to be working when compiled from source. Wrote nrect, which makes a rectangle with line of thickness n. todo... ncircle etc try to display coloured circles in a grid (like an iphone calculator. should write "where" word which shows in which blocks a word is defined. eg where Var will list block numbers, and free space in block. 17 feb 2019 Wrote "ccpoints". A pseudo circle with midpoint (200,200) radius 80 can be drawn with "200 200 80 35 ccpoints 35 ctrace" Wrote circle and fcircle but they seem quite slow. Also changed "pong" to use fcircle to show the ball. Wrote "circle" with x^2+y^2=r^2 Tried to write um/mod but it doesnt seem to be working Just behaving like u/mod um/mod ( ud u1 -- r q ) This can be used as the basis for double precision math see "math.txt" at flashforth. If quotient is too big for 16bits then its an error From math.txt ( n1 n2 -- d) : m* 2dup xor >r abs swap abs um* r> ?dnegate 16 feb 2019 wrote um* as an opcode. To write D. and UD. might need uD/ and D/ double division. Fixed u. bug caused by change in /mod (signed). Looking at pforth source. Should change JUMPS to branches? and pix to plot. Half wrote u. in source. This might be useful for D. Also it is probably better to write words like <# # #> for number conversion and use a temporary string rather than just outputting the numbers directly. 14 feb 2019 A solution to block limitations... have an index word at the top of each block. eg ## with binary indexes following indicating the start of each word in the block. Also, at the end of the block, a continuation word such as ... which indicates that the word continues in the next block. 12 feb 2019 todo write a : circle word using y=R*sin(x) and then or just use x2+y2=r2 print 4 points for each x (ie x,y x,-y -x,y -x,-y) Adapt ron geeres trig functions. write : ccpoints ( n a b -- / which returns n points on the circumference of a circle on the data stack. Then use those points to draw lots of radiating lines. Wrote "lineto", sspoints, and polar to give polar co-ordinates Turtle graphics are pretty close. A new solution: dont have an "anon" compile buffer. Just compile non-defining words straight after the last word in the dictionary, keeping a marker of the end of the last word. This has the advantage of allowing anonymous compilations of any length (not limited by the "anon" buffer. A problem: "defer test ' nop is test " is going to fail because "nop" is an opcode. So defer will only work with procedures (words). This is part of a bigger problem... that opcodes and procedures always need to be treated differently. One solution might be to include, eg: NOP, EXIT just after the opcode header for "nop" and just before the machine code for nop. This would be the execution token for nop and would allow the opcode to be called with FCALL, nop.p . It would also allow words like "is" to work just as in standard forths. Also PCALL would just work with opcodes as well and we could execute all opcodes in "immediate" mode without having to compile anything. (Currently they are being compiled to obuff.d with and EXIT and then PCALLed) The disadvantage is and extra 2 bytes per opcode. 10 feb 2019 Working on n degree rotation matrices using scaled trig values (sin*10K, cos*10K). Had the idea for tab complete for long words. Should be able to use the s/ word to implement tab complete. 9 feb 2019 Wrote the scale */ operator ( n1 n2 n3 -- n1*n2/n3) which seems to be working for signed numbers. But still hangs for eg: 1234 1234 23 */ Apparently fixed the signed /mod problem by using "idiv" signed division, with the cdw to extend sign from ax to dx:ax (which is the register pair used by idiv as dividend). But should I used cdw with u/mod as well? 8 feb 2019 Made a key? opcode using int16h ah=1. Made a sign wave graph but discovered that my /mod / mod dont work with negative numbers!! which is a big handicap. Need to look at "idiv" instruction. Wrestling once more with the code>here bug. [ create aword 1 , 2 , 3 , ] fails in source and interactively because the dictionary code point ">code" is not updated by , or c, [ create aword 1 , 2 , 3 , code>here ] Appears to fix the problem but is very inelegant. Also wrote a word "sync" in bytecode that sets >code=here if >code < here All these problems could be avoided by compiling everything into the dictionary (even anonymous definitions). But that means that after every new word definition we would have to build an anonymous header which would slow down source compilation quite a lot. 6 feb 2019 Current size of the system is: Opcodes: 1493 bytes ( 63 opcodes) Byte codes: 2920 bytes ( 74 bytecode words ) Total Size: 15550 bytes ( 328 total words ) The bytecode space has reduced slightly as we move words into source code (do/loop etc) Would like to put "loop" into source, but I dont have enough room in block 0 ( used by thru also there). Also need to change jumpz in loop to jumpnz/ljump. Wrote [call:] which compiles a call to the procedure at runtime. This is also like a double postpone word. Working on an archane word [op:] which compiles the named opcode at runtime, I think. This word is useful for writing words like if/do/loop/again etc. But there may be a simpler way. For example, write a (loop) word that performs the runtime behaviour of "loop". This avoids having to compile code when loop is compiled. This is hard to think about because the compile time for one word is the runtime for another. 5 feb 2019 Maybe "colour pong" would be a good challenge now, for this forth. And then try to compile it to native code. Would like to make a little "glyphmaker" word to create xysets which can be displayed as glyphs (either with asci blocks or with pixels). When displaying with asci blocks the aspect ration is >50% because asci glyphs are 8x16 not 8x8 Made rotations of glyphs work using rot90setn which rotates 90 degress about point n (0,1,2...) of an xyset (point set). A small animation "arot" demonstrates. Because the coordinate system of the screen is +down, -up the rotation actually appears to be happening counter-clockwise, but the matrix rotation is actually positive. A useful paradigm for paging and exiting out of a begin/again or begin/until loop if "q" is pressed... ( nn counts words, ll counts lines typed ) 0 nn ! 0 ll ! begin ( print 8 words to a line ) nn ++ 8 mod 0 = if cr ( page and prompt every 22 lines ) ll ++ 22 mod 0 = if 1 fg [char] > emit key ( quit if 'q' pressed ) [char] q = if exit fi 0 bg cr fi fi again 4 feb 2019 Could write word u.s to display the stack as unsigned values. Might be useful to have a postpost word for situations as below. Made asci box displayer "abox" Wrote rainbow for colourful text. : rb" ( print rainbow coloured text ) post s" ' rainbow literal post call, ; imm Started to write some matrix rotation code. Wrote a simple "ms" based on a loop. Could do better Thinking about asci tetris, xysets, xyglyphs, matrix rotation glyphmaker etc. Interesting maths in all this and seems quite easy to implement in forth. 2 feb 2019 Started to write "edit" based on accept.arrow. With some success. However the stack params should be changed to include a text length, because not all buffers are counted... The length could be stored in a variable. Also, showbuffer can be eliminated. So, need to change various words.. eg prevc, nextc, ctype Looking at the wordlist words such as context, current, vocab, also, only, etc. I may modify some of these words because I want the idea of namespaces to be quite strict. Started to move to unix line endings \n=asci 10 not dos endings. Ignoring asci 13=\r 1 feb 2019 Now get rid of accept.byte in bytecode. Accept.hist is useful because it has some command history. But it needs a lot more history. Also, it would be nice to be able to write this history to disk. Thus we would have a system that can be developed on itself. Also, need an "editor" which is like accept.hist but displays multiline buffers and can navigate with all arrow keys. Same strategy as with accept.hist (use showbuffer/ctype after every keystroke to show the buffer) and same stack structure ( x y A A+i ) . Made accept.hist save the buffer after /enter/ is pressed. Rewrote if0 and ifnot to reflect new longjump if version. Made "defer" and "is". These words allow installing new versions of "accept" into the shell for example. We can use is like this: ' accept.hist is accept This makes the shell (which is already compiled to use the "accept" deferred word) use "accept.hist". 31 jan 2019 Rewrote if/else/fi using jumpz/ljump combination which should allow long text in if clauses. Acceptx is almost working, only bugged by the if/fi +/- 128 byte bug. But it is working with command history (2 buffers) Removed fi.p bytecode and replaced with source. The machine needs a sign extend instruction, eg signed extend byte on stack to word. Also, should c@ and c@+ convert bytes to signed words (16 bits)? What is the utility of this? Bytes are used as relative +/- jump addresses, but not on the stack... Trying to improve dump, but should dump display signed or unsigned hex bytes, or should it display words? Wrote xytype and xyemit. 30 jan 2019 Made PIX display pixel with the forground colour. Made CURSOR opcode which sets the shape, size of the opcode. This is useful for making the text cursor disappear which is often desirable. New ideas for anonymous words: What is now the anonymous buffer will become part of the dictionary. When create executes it will check if anon exists and overwrite it, if so. When does> or semi-colon executes, it will re-establish anon 29 jan 2019 Made "acceptx" work, except for the distracting blinking cursor. Also, it only really works in text mode 3 because as far as I can see, that is the only mode that displays background colours. In other modes we can use different cursor (eg forground colour) by modifying the "ctype" word. wrote "prevc" and "nextc" to advance and regress the insert (cursor) position. 27 jan 2019 wrote delchar and insert. Thought about what happens when "move" tries to move 0 chars. It seems to work. 26 jan 2019 Modified showbuffer to use green cursor. Trying to change acceptx to do a proper backspace. need to debug. Made background colours work in video mode 3 by modifying emit to use ah=0x09 int 0x10 function. Modified "ls" to print 8 words to a line. Strange things with qemu and video modes and background colours... In video mode 3, function ah=0x09 prints forground and background colours, but in mode 16, it only prints forground colours. Also, using ah=0x09 int 0x10 then everything gets printed on one line (if there are no explicit line breaks) but with ah=0x0E int 0x10 then text is displayed on successive lines of the screen. In video mode 3, ah=0x09 cannot print any colours. In conclusion: to get background colours, we need to use function ah=0x09 int 0x10 with video mode 3, or similar. It doesnt seem possible to get background colours with function 0x0E int10 but it is with Ox09. But 0x09 is a bit more work because we have to advance the cursor. Also 0x09 print 13,10 as visible characters (not carriage return) 25 jan 2019 wrote cmove which is just "move" but can handle overlapping memory areas where A > B and A < B. Appears to be working. 24 jan 2019 Now ready to move on to acceptx using x y A A+i and "showbuffer" If words are immediate and should not be, strange errors occur. An vice versa. wrote "append" which appends characters to a counted string. rewrote "all" to load from last loaded block to n. wrote "defblock" which puts on the stack block number of the first def of the word. wrote "lo/" which tries to load all blocks up to a particular word. This is a kind of ersatz dependency loader. We can create a string constant in the dictionary with : message s" hello" ; but this contains an unnecessary jump opcode at the start of the definition. 22 jan 2019 The conversion of acceptx to showbuffer should be quite straight forward once showbuffer is working well. Bug! The phrase "10 10 pad pad 4 + showbuffer" is causing a strange bug... But the word "..sb" works ok! So interactively showbuffer doesnt work but it does within another word. An unusual bug, and its too late tonight to work it out... Working on "showbuffer" word to display a buffer at x,y on the screen with a cursor. Will change acceptx to use it. Realised that editing with arrow keys requires a different approach in "acceptx". Need to reposition cursor and display buffer on each key stroke. But will there be flicker? Fixed a getxy bug which made getxy eat top stack item. It would be good to have a word eg "showdef" that shows the source code for a word from the source blocks. Could just use a dodgy parse for next ';' to get the end of the word. Made "ss/" print the line with "typeline". But typeline could just use parse, no? Made "s/" and "ss/" work with the new (almost standard) "search" word. The idiom to print 3 things to line is 20 0 do ./ print something ii 1+ 3 mod 0 = if cr fi loop Removed the bytecode "again" version. Apparently fixed ljump.x bug (si-3 not si-2 to realign) and wrote a source "again" using ljump which seems to work. Thoughts for words: write a "para" word which is like "accept" but accepts a whole paragraph, and hopefully allows key editing. Also extend acceptx to allow arrow key movement and insertion. These are steps towards writing an editor. 21 jan 2019 Made a source "again" and a long jump version. The begin/again 128 byte bug continues to vex: The solution is to compile something like jumpz, 4; ljump -200, That is compile a short jump over the long jump. In fact we can check if the target is > +/- 128 bytes and then compile the short or long jump depending. Made "search" more standard. But ..search is freezing because of the above bug. Also need to integrate the new search in ss/ 20 jan 2019 Thoughts on the linked list dictionary. If other link fields are included then each word can belong to one or more "categories" not just namespaces. This increases the complexity of the dictionary but also the classificatory power. link field format: n:link, m:link0 etc where n,m are ordinal references to the category list. wrote "cmove" to copy data from source to destination with dest correct if areas overlap. Made wsize a bit more accurate. (mostly correct). Wrote "size" which makes wsize easier to use. Tried to change "search" to leave the found address but gave up for now. Copied some double number definitions from the Ron Geere book. 19 jan 2019 Wrote a square, octagon drawing words, from a "line" word. 18 jan 2019 words: "ns" provides a pointer to the namespace list. "name " create a new namespace (pointer) in the namespace list. 17 jan 2019 Thoughts on source structure: Keep the block structure because it is simple, but have an index which somehow give the location and lenght of each word, without naming each word... Almost fixed the behaviour of parse so that it returns rest of input when the char is not found. But one char is being truncated. Made a word ss/ which searches source blocks for a word. But whole line search is truncating one character. See BUGS Made substr which checks if a string is a substring of another. 16 jan 2019 Need to write a "copy" or "cmove" (standard) word for copying strings/data etc. The word is called cmove because when the data areas overlap only the destination is correct. Otherwise it behaves just like a copy command. This will be used by acceptx to recall history With the arrow keys. Need to improve "dump" so that it shows asci characters too and put 8 or 16 on a line. coded "if0" based on the source version of "if". Worked on acceptx. Made an alias for if0 with the idiom ": ifnot post if0 ; imm" This seems a bit counter intuitive since if0 is itself an immediate word. But it appears to work When an error occurs, made "inputcompile" print the last word compiled in the dictionary. Handy for debugging. Also, add a "block number" to the block buffer, so we know what block is currently in the buffer, also handy for debugging. Also, add a "updated" flag in the block buffer, so that we know when the buffer needs to be written to disk. 15 jan 2019 Bug! begin/again and begin/until compile to relative jumps which have a limit of 128 bytes!! This is not enough!. Need a "break" word that will jump just after the next "again" or "until". Its not necessary to use unloop in a begin/again or begin/until loop. Wrote word 's/ ' which displays all words starting with the given prefix. Also wrote "prefix" and a test loop for it. fixed a bug, bfree was eating the stack, causing .s to crash after 'df' 14 jan 2019 Bug??! unbalanced >r r> will crash the shell because pcall anon will not return properly. There should be a way to "reset the stacks" (both data and return). Eg when an error occurs Also: make "anon" a namespace (so a "sub" linked-list) which will contain command history (like the bash history file) Allow an up arrow in "accept" (use ekey) refining ideas for namespaces: We can create a new word such as :: This will search for in the namespace list. If not found it will create a new namespace variable in the list (with a null pointer since there are no words in this namespace, yet). Then it will create the in the new namespace. Creating the new word involves creating a word with a "zero" backlink (since this is the top word in this dictionary) and then updating the namespace variable to point to this new word (since it is the last word in the list). ::var Will work in a similar fashion 11 jan 2019 An interesting idea!!!: All anonymous commands should be compiled to the dictionary!! That is, words entered interactively should be compiled to the "anon" buffer, (as is done already), and then copied to the end of the dictionary with the name "anon0". The only major change is that the anon buffer should also have a back link to the last word in the dictionary. Also, new defined words are first created in the anon buffer and then copied to the dictionary. This may even resolve the whole here>anon and here>code problems. (Also anon2 is renamed anon3, anon1 is renamed anon2 and anon0 is renamed anon1... this allows for a simple "command history", at least 3 previous commands. Also, this idea is a step towards "dependency compiling", which involves trying to compile a word even even if its dependencies (constituent words) are not in the dictionary. Code is compiling. There is a "creation" namespace: All new words created will be put into that namespace (linked list) until further notice. Then there is also the "search" namespace(s) which are an ordered list of namespaces to search for the given word. The first one found is executed/compiled. And finally there is a unique-name namespace which only applies to the word immediately following it. For example: "forth.math pi" will only search for and exec/compile the word "pi" in the forth.math namespace While fiddling with the code yesterday, about 17 words mysteriously disappeared from the loaded dictionary. The words source, load and inputcompile should return a flag indicating success or failure. This should allow error trapping and easier debugging. Thoughts: when loading blocks (or namespaces) a better message should be displayed (we could put that in "thru") Namespaces should be a namespace! This cryptic phrase means that a word which is a namespace (eg: forth.core) should be in the namespace "namespace". Now, the word "dup" for example is in the namespace "forth.core". Clear as mud. But by putting namespace words in their own namespace we can dealwith them differently. Maybe opcodes should also be in their own namespace but I havent thought that through. 24 dec 2018 Need to solve several problems before writing more forth code. Dependency problems. So a word should be able to look up obtain and compile its dependencies. This is not so hard: the process is, look in the forth dictionary, if the word is not there look on the disk, if the word is not there, look on the net using fullname. Namespaces will be handled by interleaving the lists within the same dictionary. Each word will only link back to the next word in its own namespace (or domain). So there will be several linked lists interleaved in the forth dictionary. At the top of the dict there will be a "start-link" table, associating namespaces with where to start searching in the dictionary. This system should be much faster for look up and compiling that having a domain name prefix field in every word. The other problem in being able to search the code on disk for a word without compiling all words. This may be handled with a simple character lenght field at the start of each word. This allows the coder to skip over that word if it is not the searched for word. Compiling a word with dependencies: Start to compile a word to a "compile buffer" (not to the dictionary). If the word compiles fine then copy to the dict, if not leave a space, search for the dependency word on disk/net and start compiling the dependency word to the compile buffer after the incomplete word. Then copy to the dict. This is recursive. 24 august 2018 A few more move vectors for chess pieces. Thought about words ,{{ } and {{ } which compile byte data to a given address. eg c,{{ 1 2 3 4 5 } or 1234 c{{ 1 2 3 4 } 22 august 2018 Created the chess vectors for knight and bishop on a 12x8 board See the arduino book for a sketch of how to code chess in this forth. Source code on disk needs to be stored in a structured fashion. Or maybe have shadow information about start and end of words. late july 2018 Started a port of this machine to the atmega328p avr chip (the usual "arduino" chip). Then got distracted coding timer/counters in avr asm. 19 july 2018 A big challenge is going to be accomodating Harvard architecture microcontrollers within this machine. Where code and data space are separate. Flashforth may have some answers for this. 17 july 2018 Should use asciidoctor and asciidoc format to create a printable version of this source code. Wrote a palindrome word, which uses recursion, and is possibly the simplest recursive descent parser... Did some work on the 'deps' word, still not recursive. still grappling with code>here problems. hard to visualise. The simplest way seems to be to update the >code point if code < here in the here! word. But this is not working. Machine: 4th.x86.topdx.17july2018-11pm Opcodes: 1410 bytes ( 62 opcodes) Byte codes: 3078 bytes ( 82 bytecode words ) Total Size: 11335 bytes ( 250 total words ) 16 july 2018 might be good to have a begin/until which has a counter with no limit. wrote "page" which prints text one screen at a time. wrote 'println' which is like type but only prints one line. Hopefully fixed a bug in li/0 which sets a list to zero probably will put code in c, and , to update >code if necessary. 11 july 2018 made some progress on : deps. fixed a bug in list.addu more 'create' bugs... The following line doesnt work [ create pawn 1 c, 2 c, 3 c, ] This is because the >code pointer is not updated after the c, words. So, 'here' is updated, I think I need to change the way 'here' and >code work. 6 july 2018 wrote 'within'. ppm image format easiest to display, or pgm as a glyph a random number series. an editable buffer, test.tonumber and test.type removed from bytecode 4 july 2018 also accept can be put in source. wrote a source 'accept' with a maximum number of chars. used a helper variable. wrote a 'continue' which jumps out of an if clause and back to begin. But will fail for 2 nested ifs tried to write an accept with arrow keys but got lost. simplest random seed using the clock, but need a series. eg var R : rnd clock drop 16 mod ; : r' R @ getnext R ! ; 2 july 2018 Would like to write 'accept' as source with some command history. cleaning up. removed old some bytecode words like 'seecomp' and 'one' which were used to debug the system. Left dotstack.p as bytecode because it could be useful to debug bytecode words. 1 july 2018 Moved [ and ] into source. wrote a new shell in source. opcodes: 1410 bytes ( 62 opcodes) bytecode: 3689 bytes ( 89 bytecode words ) total: 9427 bytes ( 221 total words ) 30 june 2018 wrote a source .S version of .s should add some command line history and write that history to blocks, so that work is not lost. write accept as source and allow arrow keys to edit. Multiline accept. Make an asci sperm whale 29 june 2018 asci animals: could do sperm whale, python. 28 june 2018 Writing a little chess: code. Also fixed a cbw sign extension problem for c@ c@+ probably caused in the transition to the top dx engine. Tidying up lib.p block0 now loads all the other blocks. Made numbers and opcodes work in immediate state. The ops get compiled to a short buffer and executed immediately. working on the buffer editor ed: so as to try to make this forth self-supporting. That is, to be able to edit and develop the system with no OS. Need lots more 'line arithmetic' to make it work. Also, how to edit over rs323 connection. eg vi etc opcodes: 1404 bytes ( 62 opcodes) bytecode: 3852 bytes ( 212 words ) total: 9059 bytes 27 june 2018 An x86 assembler can work like this code: doit ax inc, ax bx sub, ;code So the operand comes first and is pushed onto the stack, then the inc, word compiles the mnemonic with its operand. This raises the questions of wordlists and vocabs. ax is a word in the assembler word list. Recursive factorial, and arithmetic, calculate e exponent. Put domain fields in some words. The recursive factorial is very succint, like gcd. 26 june 2018 All this needs reconsideration. But the domain table idea seems sound at the moment. (See later notes about an interleaved dictionary for namespaces) This is claytons object orientation. Domain table is like this domain.table: db 1, 0, 3, '4th' db 2, 1, 1, 4, 'set' ; extra space here for new domains the 1st number is the domain symbolic constant, used in the domain field of the compiled word. The second is a count of how many prefix domains (none for 4th) then comes a list of prefix domains as symbolic constants, then the counted string name. This is compact for compilation but allows all names in the dictionary (and outside of it) to be unique. Claytons oo is like this * define the object and just return a reference to the obj at runtime : set create allot blah blah does> blah, not much ; imm :dom the word ':dom' compiles a new domain for the last compiled word. The new domain 'set' with possible prefix domains will be appended to the domain.table if there is sufficient room. So defining words should automatically set the domain of defined words to the same as themselves? * create an instance of the object 20 set ss When set create 'ss' it probably should sets its domain automatically to 'set'? * create some words which operate on a ref to the instance eg : additem ( address -- ) blah blah ; * set the domain of the new word to set dom set. So additem has a full name of '4th.set.additem' but it could still be used by a different object. * use the new method on the instance ss m> additem 'm>' can use the reference to ss (left on the stack by ss) to get its xt and therefore its domain. Then use that domain to do a special find only searching for that domain. m> could change the domain used by 'find' when searching for a word (eg 'additem') in the dictionary. So find will only find 'methods' of 'set' because they are the only words with that domain. But normally these words/methods will be invisible to find because the domain will be '4th' or somesome. Write a word that prints fully qualified names using the domain field in the compiled word eg 4th.set.additem etc Apart from using this as a claytons OO system, it is a useful step towards universal unique locatable names in source code. Thinking about domain fields and how to use them. Have got this schema so far: domain field is 1 byte in each word. the 'find' word has an implicit or explict domain during its search. Or a list of domains. So when we do a normal 'find' we wont find words with different domains unless we explicitly search for them. This may be parallel to forths 'wordlist' concept, same same but different. Also, we can take one step towards an object system by hiding object methods in their own domain. 25 june 2018 Working on the ed: edit buffer object. This seems promising. Once we can edit a buffer then the system becomes almost self sustaining. Started to put in domain fields. (revise to namespace) Wrote a list: data type that has an addu "method" for adding unique elements as well as a normal add method. I think the code is more readable. Wrote allot0, dump and dumpw wrote !1+ but not !1- That is, decrement the value at the address and store new value there. Modified list: so that object reference is no longer left on stack. Wrote 'thru' to load a series of blocks. .' prints in what word an address is found, and the offset from the start of the word. Thinking about how to code data structures. Put one reference on the stack and make 'methods' that access and manipulate part of the structure. Also, make the methods use a simple reference to the object. Eg an editing buffer has capacity, insertion point and pointer to buffer. 24 june 2018 Found a bug in r@. Needed to dig under the word return pointer (of r@ itself). One extra ';' causes fatal errors. made the 'unloop' word which is needed for exiting from loops before the counter has finished. wrote erase and fill. Wrote set.ls and set.add and set: which appear to create a set that only contains unique items (16bit elements). opcodes: 1302 bytes bytecode: 3847 bytes total: 8274 bytes 23 june 2018 made atxy and getxy as opcodes to obtain and set the current cursor position. wrote 'arrow' to move cursor around. Now the trick is to move the insertion point around in a text buffer. This is a map. Cant do an exit from a do/loop, need an unloop or 'leave' word which will get the loop parameters of the return stack. The create bug still exists but can be avoided by putting does> at the end of defining words. Will try to write ed which allows basic editing of a buffer (1024bytes) which can then be saved to disk with 'save'. opcodes: 1270 bytes bytecode: 3839 bytes total: 7770 bytes 22 june 2018 made write.x appear to work. Wrote 'save' which saves the first buffer to disk block n. This maybe enough to use the os to develop itself. Only tested on qemu. Need to test on real hardware. But need some kind of editor to edit buffers/blocks. opcodes: 1245 bytes bytecode: 3829 bytes total: 7322 bytes included a "sanity-check" in the block writing routine which checks that the number 31415 is the 8th byte of the boot sector 21 june 2018 Since the aim is to achieve a minimum size and simplicity while maintaining portability, it is useful to record the system size. opcodes: 1231 bytes bytecode: 3829 bytes total: 7280 bytes Regarding the create runtime bug (dictionary code pointer not advanced etc): Wrote 'def' to set the defining control bit in a word. After consideration, we see that defining words, when they exit at run-time need to do essentially what ; semicolon does at run-time. However, when a defining word runs, there is no semicolon. This arises because the system compiles even code which is entered interatively. When a defining word stops defining, the compile point needs to be switched back to the 'anon' buffer and the >code point needs to be updated. One solution, is to make CREATE set a 'def' control bit in the count byte of the name. So create becomes an immediate word and compiles a call to (create) which is just the same as the current create. Then when semicolon executes it checks def control bit, and if set, compiles a context switch. This bug also effects does>. The does> bug seems fixed by essentially putting ; semicolon code into (does>) We could write (;) a runtime semicolon. 20 june 2018 Struggling with this code>here bug in defining words. One hack is to define var like : var create 0 , code>here ; imm but that is inelegant. When I put code>here into c, I seem to get a complete meltdown, maybe a stack overflow, or infinite loop. Not sure why yet. Discovered a bug in the way that code>here is called at the end of a new defining word, so that space is not allocated for the data field of the new word. So when we execute a defining word the defined word doesnt get any data space. This is tricky, maybe c, , and allot etc also need to update >code or call code>here. Or in here>anon call code>here first so that the code compile point is set correctly Wrote 'mname' which shows the machine name and signature, and maybe opcodes. Edited the bash script cos.sh (and .bashrc) so that todays date is inserted in the machine name when the code is compiled. This helps to know what version we are running. 19 june 2018 in' is a useful word. Finds the word in which a memory address occurs (this is not its standard name). Wrote a new bash function ccos so that I can compile different versions of the machine easily. 18 june 2018 Realised that a unique machine name is useful for installing or compiling new opcodes. The name indicates the underlying hardware and the 2 stack machine implementation strategy. Converted to holding TOS (top-of-stack) in the dx register. This should improve performance, especially for calculation intensive operations. But the performance difference is not very noticable at the moment. Need better error reporting in IN, or item, so we can work out where something is going wrong. If exec.x was an opcode and could call itself, then using call/ret for each opcode may have some useful and interesting consequences. But real machines dont seem to do this (an opcode which can call itself), and I cant think of any immediate benefit. Converted call/ret in exec.x/opcodes to jmp [] etc. This appears to be working. Thinking about using jit just-in-time opcodes which would allow the compilation to machine code of the most used words. thus improving performance. Conversion appears initially successful. 17 june 2018 will try to convert 'calls' in exec.x to jumps. which should save code-space and time. Old version saved to os.call.asm 16 june 2018 fixed do/loop to make it standard. fixed sed preprocessing for 'times' lines. wrote write.x but havent tested. wrote timeloop to do simple performance testing. appeared to fix read.x by using int 13h ah=8 function to get disk parameters. On the asus computer, sectors=63 and sides=32 drive=0 15 june 2018 Could write a 'set' type, with a capacity and length, with an 'add' method, which would only add a 16bit value if it wasnt already in the set. This would be useful for building a set of unique xts (execution tokens) when finding the compiled dependencies for a given word. Also, could adapt this technique to a 'point set' where each element in the set is 2 16bit values, which could be used for making a list of block number + offsets for a dependency compile from source (only the required word and its dependencies are compiled). Realised that the exec.x function could just jump to the opcodes, rather than calling them, which would simplify the coding of each opcode. made 'splash' show opcode and byte codes sizes. changed ' to make it more standard. rewrote ." to simplify trying to write a new read.x to calculate chs for floppy emulation, but need to print off and analyse. Thought of a dependency compiler creating a list of block numbers and offsets. 13 june 2018 realised that if fi begin again etc can all be coded in source. 12 june 2018 made a splash screen 'splash'. Saw how the scale operator */ is useful for multiplying by fractions without losing precision eg: 100 2 3 */ gives 2/3rds of 100. The intermediate result is a double number. could make 'state' have 3 states, not 2. ie immediate/delegate/compile in immediate, everything is compiled, in delegate, the word itself decides whether to compile or execute, and 'compile' where everything gets compiled even immediate words. 11 june 2018 can define [char] like this. : [char] postpone char postpone literal ; defined ." Also postpone could have a syntax like [: ... :] which basically would force even immediate words to be compiled. This would just be a branch in the item,/compile, word. fixed parse so that it doesnt include final delimiter started a sed preprocessor in a separate file 'os.sed' Need to stop os.sed from mangling labels like 'block1:' etc. Realised that postpone is an important word. It just compiles an FCALL to the word even if the word is immediate. Can be defined in source. Thought about how to emulate opcodes in high level forth. The opcode calls a word similar to FCALL that pushes address of emulating word on call stack. But need to do some very simple assembling to get the write address into the machine code. Does 'call,' need to be immediate? 10 june 2018 made 'postpone' which compiles an fcall to immediate words like sliteral (otherwise they would execute immediatly). This is because we want sliteral to execute when parse has finished (at run time) not at compile time. made s" using postpone. did sliteral and (does>) the runtime behaviour of does> and wrote does> . Made call, ( xt -- ) to compile an FCALL to xt realised the importance of (does>) and other (...) words. Otherwise we would have to compile lots of code while executing 'does>' 9 june 2018 Made the preprocessor put a 13,10 at the end of each line because plain text source will have them. This allows a comment-to-end of line syntax which is handy. Fixed a problem in HERE>CODE. This word executes the ANON buffer but was not resetting it, so words like IMM were executing multiple times. FIB stopped working today, not sure why Made a LITERAL word to use with CHAR in colon defs more or less fixed PARSE. so comments like ( a b --) are easy now. eg: : ( [char] ) parse ; imm 8 june 2018 wrote a very basic sed preprocessor and a bash function to use it (see comments at top of file about how to compile and run). But need a forth comment syntax to make it worthwhile, and to get that I need PARSE to work, either in source or bytecode. rewrote INWORDS and FINDWORDS as source. These words are only really useful as a testing mechanism. 7 june 2018 wrote r.v.nobles recursive euclid "gcd" function. Recursive functions work on this forth!! Copied a recursive FIB fibonacci word. And I didnt even think about them when I was coding! Rewrote keycode as source. When loading source code into a buffer, it might be good to get rid of extra white space... Defined char but realised that there is a problem with the use of char in a colon def, because the character code is pushed onto the stack at compile time, instead of compiling a literal to push onto stack at run time 6 june 2018 Thought that PCALL could be modified to execute opcodes as well. Not so easy. ACCEPT uses the rstack to save the buffer address, but 2DUP makes this unnecessary. Also a char limit would be good In this system, it seems all defining words must be immediate??? So we must do : variable create 0 , ; immediate : var create 0 , ; imm need to fix other parse now. using CREATE in : not so good ? Thinking about how to implement immediate execution of opcodes and literal numbers (to push onto the stack). Could compile to a small anonymous immediate buffer and execute immediately. Wrote CREATE. Appears to be working. Made : COLON and ; use CREATE which appears to be working. 5 june 2018 fixed WPARSE to use the >IN stream and got : COLON to use it. Thought of the idea of a machine "signature". Which is just a list of opcodes plus mappings. eg 1-5,7-33,34:2101 This means that the given machine has standard opcodes 1-5 and 7-33 and the standard opcode 2101 which is mapped to 34. Made a byte code version of [ and ] for testing. Started CREATE. wrote WPARSE for parsing whitespace delimited words, skipping initial whitespace. opcodes cant execute immediately! nor numbers! fix? WPARSE advances the input stream with IN+ >CODE is a pointer but HERE is a value and >IN is 2 values This is a bit confusing and not consistent. Could make >CODE a value, and CODE a pointer. wrote a HERE>CODE word which sets the here var to the next available location in dictionary. It is called by CREATE and thus all defining words. It also writes an EXIT to the end of ANON and executes anon with FCALL This ensures that what is in the anonymous compile buffer ANON will always get executed before new code is written to the dictionary. We can call this a "context switch". The ANON compile buffer is where non-defining interactive commands are compiled to. 4 june 2018 Wrote a whitespace word WSPACE that returns a flag indicating if a char is tab=9 cr=13 space=32 or 0 etc This can be used in WPARSE Wrote LOAD which just loads the first block. A better LOAD would be : load 2* block1 + 2 first read first 1 K source ; which should load any block number eg 3 load. But we should also implement block & buffer. And started to move code into that source code block from lib.p rewrote >IN and IN0 so that they would use a length variable for input streams. Realised that SOURCE and IN, are different, because SOURCE establishes a new input stream. We dont seem to have to save the current one because, by the time it executes the current stream has been compiled... but, if we execute SOURCE immediately then we may get serious problems. 3 june 2018 made an word IMM which sets the last word in the dictionary to immediate. Thinking about the exec function which executes bytecode. should this be able to call itself? I cant think of any analogy in a real machine, so I dont think so. Could be good to have a word which pushes the address of the opcode table onto the stack to allow manipulation of opcodes from within forth 2 june 2018 Changed LAST to be a pointer. Made a STATE variable Put state test into ITEM, WORD. But [ and ] words must be immediate themselves! or they dont work. Made the READ opcode sort of working (up to sector 18 ?) but need to grapple with the idea of emulated disk geometries and convert sector number to head+cylinder+sector number etc Want to make this opaque, so that the opcode handles this mess and the code can just treat the disk as an enormous array of sectors/blocks. After that can code buffer and block words. Maybe use last byte of block to store "update" bit and block number. This info is used by buffer and block words to determine if a read and/or write to disk is necessary. Will just have one source buffer initially for simplicity. Think I am close to achieving a robust, compact, and powerful system. Once LOAD/BUFFER/BLOCK are working well, we can rewrite many words as source code, thus reducing the core even further. Still need to fix DO and LOOP And write VAR/VARIABLE, CON/CONSTANT etc. Also could try to wrap core and source blocks in a super basic fat12 file system so that source code can be edited on another operating system? But even FAT12 looks complicated! 29 may 2018 writing out some standard forth words in %if0 block Will need to preprocess %if0 block below to put "db ' " etc in front of every line of some forth source. squareroot word 28 may 2018 thinking about CREATE and DOES>. realised that the implementation of these words is not that difficult. DOES> needs to compile an FCALL in new defined words to the code immediately after it, as well as an EXIT for the defining word. Probably will do this by jumping over parameter field. 23 may 2018 Made EKEY work on x86 architecture. Made a LOOP immediate word. but its not like the standard forth LOOP at the moment. 15 May 2018 Finally got a : compiler working, so new words can be added to the dictionary. Wrote inputcompile (IN,) to compile the input buffer to the HERE pointer. Made a basic foreground colour changer just for fun FG opcode and a video mode changer VID for colour vga style monitors 11 May 2018 separated this forth-like system into a new file. Up until now, have been developing as part of the osdev booklet. 10 june 2017 made a return stack with es:di and made fcall.x and exit.x use the return stack, apparently successfully which allows nested procedures. %endif ; }docs BITS 16 [ORG 0] jmp 07C0h:bootload ; Goto segment 07C0 db 'pi:' dw 31415 ; magic number drive: db 0 ; a variable to hold boot drive number db 'boot:now' bootload: mov ax, cs ; the code segment is already correct (?!) mov ds, ax ; set up data and extended segments mov es, ax mov [drive], dl ; save the boot drive number mov ax, 07C0h ; Set up 4K stack space after this bootloader add ax, 288 ; (4096 + 512) / 16 bytes per paragraph mov ss, ax ; with a 4K gap between stack and code mov sp, 4096 ; save the DL register or else dont modify it ; it contains the number of the boot medium (hard disk, ; usb memory stick etc) ; The 'floppy' Drive is NOT necesarily 0!!! reset: ; Reset the virtual floppy drive (usb) mov ax, 0 ; mov dl, [drive] ; the boot drive number (eg for usb 128) int 13h ; jc reset ; ERROR => reset again readdisk: mov ax, 1000h ; ES:BX = 1000:0000 mov es, ax ; es:bx determines where data loaded to mov bx, 0 ; mov ah, 2 ; Load disk data to ES:BX ;mov al, 8 ; Load 8 sectors 512 bytes * 8 == 4K mov al, 16 ; Load 16 sectors 512 bytes * 16 == 8K mov ch, 0 ; Cylinder=0 mov cl, 2 ; start sector=2 (sector 1 is the boot sector) mov dh, 0 ; Head=0 mov dl, [drive] ; int 13h ; Read! jc readdisk ; ERROR => Try again or exit jmp 1000h:0000 ; Jump to the loaded code times 510-($-$$) db 0 ; pad out the boot sector ; (512 bytes) dw 0AA55h ; end with standard boot signature ; **** ; this below is the magic line to make the new memory offsets ; work. Or compile the 2 files separately ; https://forum.nasm.us/index.php?topic=2160.0 section stage2 vstart=0 jmp start ; aliases for each bytecode, these aliases need to be in the ; same order as the pointer table below ; The nasm code below gives values of 1,2,3,4,5 etc to each ; bytecode alias. A new opcode can be inserted without having ; to update all the following opcodes. DUP equ 1 DROP equ DUP+1 SWAP equ DROP+1 OVER equ SWAP+1 TWODUP equ OVER+1 FLAGS equ TWODUP+1 DEPTH equ FLAGS+1 RDEPTH equ DEPTH+1 RON equ RDEPTH+1 ROFF equ RON+1 STORE equ ROFF+1 STOREPLUS equ STORE+1 FETCH equ STOREPLUS+1 FETCHPLUS equ FETCH+1 CSTORE equ FETCHPLUS+1 CSTOREPLUS equ CSTORE+1 CFETCH equ CSTOREPLUS+1 CFETCHPLUS equ CFETCH+1 COUNT equ CFETCHPLUS ; count is an alias for c@+ EQUALS equ CFETCHPLUS+1 NOTEQUALS equ EQUALS+1 LESSTHAN equ NOTEQUALS+1 ULESSTHAN equ LESSTHAN+1 LIT equ ULESSTHAN+1 LITW equ LIT+1 EMIT equ LITW+1 AKEY equ EMIT+1 KEY equ AKEY+1 EKEY equ KEY+1 GETXY equ EKEY+1 ATXY equ GETXY+1 PLUS equ ATXY+1 MINUS equ PLUS+1 INCR equ MINUS+1 DECR equ INCR+1 NEGATE equ DECR+1 DPLUS equ NEGATE+1 LOGOR equ DPLUS+1 ; logical or LOGXOR equ LOGOR+1 LOGAND equ LOGXOR+1 SCALE equ LOGAND+1 DIVMOD equ SCALE+1 UDIVMOD equ DIVMOD+1 UMIXDIVMOD equ UDIVMOD+1 TIMESTWO equ UMIXDIVMOD+1 MULT equ TIMESTWO+1 UMULT equ MULT+1 UMIXMULT equ UMULT+1 FCALL equ UMIXMULT+1 PCALL equ FCALL+1 EXIT equ PCALL+1 LJUMP equ EXIT+1 JUMP equ LJUMP+1 JUMPZ equ JUMP+1 JUMPF equ JUMPZ ; jumpf (false) is an aliase for jumpz JUMPNZ equ JUMPZ+1 JUMPT equ JUMPNZ ; jump-true alias for jump-not-zero RLOOP equ JUMPNZ+1 DIVTWO equ RLOOP+1 READ equ DIVTWO+1 ; loads sectors from disk WRITE equ READ+1 ; writes sectors to disk (usb etc) FG equ WRITE+1 ; foreground colour for text and pixels BG equ FG+1 ; background colour CURSOR equ BG+1 ; set the screen cursor shape (0=hidden) CLS equ CURSOR+1 ; clear screen VID equ CLS+1 ; video mode ; changed PIX to PLOT PLOT equ VID+1 ; plot one pixel on screen at xy, with colour FG GLYPH equ PLOT+1 ; display glyph on screen RTC equ GLYPH+1 ; real time clock CLOCK equ RTC+1 ; number of clock ticks since midnight NOOP equ CLOCK+1 ; no operation & end marker ;*** control bits and mask IMMEDIATE equ 0b10000000 MASK equ 0b00011111 ; Machine signature goes here ; machine name: eg x86.v1 opcodes and mappings ; the machine name can be used to install or compile new ; opcodes for this particular architecture ; but should this be an opcode or a forth word? machine.doc: ; db ' allows access to the machine name, signature and opcodes ' ; dw $-machine.doc machine: dw 0 db 'machine', 7 machine.p: db LITW dw machine.name db EXIT machine.name: ; the name of the machine, including on what chip it is ; implemented and a mnemonic about how it is implemented ; maybe include compile date in this machine name. db machine.sig-machine.name-1, '4th.x86.topdx' ; maybe a machine description here ; the machine signature which is like an opcode map machine.sig: db 4, '1-55' ; a table of code pointers. The pointers have the ; same offset in the table as the value of the opcode ; Zero is the false flag in Forth, so it is handy not to ; have any opcode defined for forth op.table: dw 0, dup.x, drop.x, swap.x, over.x, twodup.x dw flags.x, depth.x, rdepth.x dw ron.x, roff.x dw store.x, storeplus.x, fetch.x, fetchplus.x dw cstore.x, cstoreplus.x dw cfetch.x, cfetchplus.x dw equals.x, notequals.x, dw lessthan.x, ulessthan.x, lit.x, litw.x dw emit.x, akey.x, key.x, ekey.x, getxy.x, atxy.x dw plus.x, minus.x, incr.x, decr.x, neg.x dw dplus.x dw logor.x, logxor.x, logand.x dw scale.x, divmod.x, udivmod.x, umixdivmod.x, timestwo.x dw mult.x, umult.x, umixmult.x dw fcall.x, pcall.x, exit.x dw ljump.x, jump.x, jumpz.x, jumpnz.x, rloop.x dw divtwo.x dw read.x, write.x dw fg.x, bg.x, cls.x, cursor.x, vid.x, plot.x dw glyph.x dw rtc.x, clock.x ; could put just-in-time opcodes here. ; I think zero is a better teminator no? Yes because ; -1 is a valid address although unlikely address!!! dw noop.x, -1, 0, 0, 0, 0 ; fill the table with zeros, so we can add more ; in code... ; this is the function which executes the byte codes ; takes a pointer to the code. Jumps are relative to the first ; byte of the jump instruction. This is not an opcode because ; it represents the machine itself... exec: dw machine.p db 'exec', 4 exec.x: ; get exec.x return address out of the way. ; Actually exec.x never returns! (since SHELL is an infinite loop) pop word [returnexec] ; save return ip pop si ; get pointer to code exec.nextopcode: xor ax, ax ; set ax := 0 lodsb ; al := [si]++ cmp al, 0 ; zero marks end of code je .exit .opcode: mov bx, ax ; get opcode (1...nop etc) into bx shl bx, 1 ; double bx because its a word pointer ; each opcode jumps back to exec.nextopcode. This improves speed ; compared to doing call/ret. ; Can hold top of stack in dx "sub dx, bx " etc jmp [op.table+bx] ; use opcode as offset into opcode table ; check for stack underflow here ??? ; Actually this is never executed because each opcode ; jumps straight back to exec.nextopcode: directly jmp exec.nextopcode .exit: ;This never exits. shell is infinite loop, but it could exit... push word [returnexec] ; restore fn return ip ret returnexec dw 0 plus.doc: ; db 'add the top 2 elements of the stack.' ; db ' ( n1 n2 -- n1+n2 ) ' ; db ' This opcode is agnostic about whether the two 16 bit ' ; db ' numbers are signed or unsigned. The flags opcode can be ' ; db ' checked to see if there is an overflow or carry. ' ; dw $-plus.doc plus: dw exec.x db '+', 1 plus.x: pop bx add dx, bx jmp exec.nextopcode ; better to use add with carry on 16bits ; and add with overflow. Then we can implement dplus easily dplus.doc: ; db 'add the 2 double numbers ' ; db ' ( d D -- d+D ) ' ; db ' This opcode is agnostic about whether the two 16 bit ' ; db ' numbers are signed or unsigned. The flags opcode can be ' ; db ' checked to see if there is an overflow or carry. ' ; dw $-dplus.doc dplus: dw plus.x db 'd+', 2 dplus.x: ; TOS (dx) has high word of first double mov ax, dx shl eax, 16 pop ax ; lower word here pop dx shl edx, 16 pop dx add edx, eax push dx ; lsw become NOS shr edx, 16 ; msw becomes TOS (dx) ; a stack method to convert singles to doubles ; push word [wHigh] ; push word [wLow] ; pop dword [dwResult] jmp exec.nextopcode minus.doc: ; db 'subtract the top element of stack from next top' ; db ' ( n1 n2 -- n1-n2 ) ' ; dw $-minus.doc minus: dw dplus.x db '-', 1 minus.x: pop ax sub ax, dx mov dx, ax ; tos=dx jmp exec.nextopcode incr.doc: ; db ' ( n -- n+1 ) ; db 'Increment the top element of the data ; db 'stack by one. ' ; dw $-incr.doc incr: dw minus.x db '1+', 2 incr.x: inc dx jmp exec.nextopcode decr.doc: ; db ' ( n -- n-1 ) ; db 'Decrement top element of the data stack by one. ' ; dw $-decr.doc decr: dw incr.x db '1-', 2 decr.x: dec dx jmp exec.nextopcode ; Called "negate" in standard forths. Called "minus" in older ; forths (figforth?). neg.doc: ; db ' ( n -- -n ) ; db 'Negates the top item of the stack' ; dw $-neg.doc neg: dw decr.x db 'neg', 3 neg.x: neg dx jmp exec.nextopcode logor.doc: ; db ' ( n1 n2 -- n1 V n2 ) ; db 'the logical OR of n1 and n2' ; dw $-logor.doc logor: dw neg.x db 'or', 2 logor.x: pop ax or dx, ax jmp exec.nextopcode logxor.doc: ; db ' ( n1 n2 -- n1 V n2 ) ; db 'the logical or of n1 and n2' ; dw $-logxor.doc logxor: dw logor.x db 'xor', 3 logxor.x: pop ax xor dx, ax ; top of stack == dx jmp exec.nextopcode logand.doc: ; db ' ( n1 n2 -- n1 && n2 ) ; db 'the logical and of n1 and n2' ; dw $-logand.doc logand: dw logxor.x db 'and', 3 logand.x: pop ax and dx, ax jmp exec.nextopcode ; no no, should be 2/ not /2 divtwo.doc: ; db '(n1 - n1/2) ' ; db ' divide n1 by 2 ' ; dw $-divtwo.doc divtwo: dw logand.x db '/2', 2 divtwo.x: shr dx, 1 ; do dx := (dx+1)/2 /tos=dx jmp exec.nextopcode ; this is unsigned division, which is not usually what we want udivmod.doc: ; db '(n1 n2 - remainder quotient) ' ; db ' divide n1 by n2 and provide remainder and quotient. ' ; db ' n2 is the top item on the stack ' ; dw $-divmod.doc udivmod: dw divtwo.x db 'u/mod', 5 udivmod.x: ; maybe could optimise by doing div dx ?? mov bx, dx ; divisor is top of stack. tos=dx, xor dx, dx ; set dx := 0 pop ax ; dividend is next element div bx ; does dx:ax / bx remainder->dx; quotient->ax push dx ; put remainder on stack mov dx, ax ; put quotient on top of stack jmp exec.nextopcode ; this is signed division divmod.doc: ; db '(n1 n2 - remainder quotient) ' ; db ' divide n1 by n2 and leave remainder and quotient. ' ; dw $-divmod.doc divmod: dw udivmod.x db '/mod', 4 divmod.x: ; maybe could optimise by doing div dx ?? mov bx, dx ; divisor is top of stack. tos=dx, xor dx, dx ; set dx := 0 pop ax ; dividend is next element cwd ; sign extend ax -> dx:ax idiv bx ; does dx:ax / bx remainder->dx; quotient->ax push dx ; put remainder on stack mov dx, ax ; put quotient on top of stack jmp exec.nextopcode scale.doc: ; db '(n1 n2 n3 - n1 M* n2 / n3) ' ; db ' do n1*n2 (2 cell result) and divide by n3 (1 cell result) ' ; dw $-scale.doc scale: dw divmod.x db '*/', 2 scale.x: mov bx, dx ; save t-o-s (n3) for later pop ax ; n2 pop dx ; n1 imul dx ; do dx:ax := ax*dx idiv bx ; does dx:ax / bx remainder->dx; quotient->ax mov dx, ax ; put quotient on top of stack jmp exec.nextopcode ; unsigned. This is not working so far. umixdivmod.doc: ; db '(ud n - rem quo) ' ; db ' divide unsigned double by n and provide remainder and quotient. ' umixdivmod: dw scale.x db 'um/mod', 6 umixdivmod.x: xor ebx, ebx ; ebx=0 mov bx, dx ; divisor is top of stack. tos=dx, ;pop dx ; high cell of dividend is higher on stack xor edx, edx ; set dx := 0 xor eax, eax ; pop ax shl eax, 16 ; mov high cell of dividend ; or try edx:eax pop ax ; low cell of dividend div ebx ; does edx:eax ? / bx remainder->edx; quotient->eax push dx ; put remainder on stack mov dx, ax ; put quotient on top of stack jmp exec.nextopcode timestwo.doc: ; db '(n1 -- n1*2 ) ' ; db ' double n1. This basically performs a ' ; db ' left shift on the bits in n1 ' ; dw $-timestwo.doc timestwo: dw umixdivmod.x db '2*', 2 timestwo.x: shl dx, 1 ; tos=dx jmp exec.nextopcode mult.doc: ; db '(n1 n2 -- n1*n2 ) ' ; db ' signed multiplication ' ; dw $-mult.doc mult: dw timestwo.x db '*', 1 mult.x: pop ax imul dx ; do dx:ax := ax*dx ; need to set some overflow flag here if dx<>0 mov dx, ax ; result in top of stack, tos=dx jmp exec.nextopcode umult.doc: ; db '(n1 n2 -- n1*n2 ) ' ; db ' unsigned multiplication ' ; dw $-umult.doc umult: dw mult.x db 'u*', 2 umult.x: ;mov bx, dx ; tos=dx ; we dont use the result in dx here so could not do this ;xor dx, dx ; set dx := 0 pop ax mul dx ; do dx:ax := ax*dx mov dx, ax ; result in top of stack, tos=dx jmp exec.nextopcode ; The high order 16 bits of a double number is on top of the ; stack. umixmult.doc: ; db '(a b -- d / do a*b and leave double result d, unsiged ) ' ; db ' unsigned mixed multiplication ' umixmult: dw umult.x db 'um*', 3 umixmult.x: pop ax ; next-on-stack into AX mul dx ; do dx:ax := ax*dx push ax ; result in top 2 stack items, high item is TOS jmp exec.nextopcode fcall.doc: ; db 'Call a virtual proceedure on the bytecode stack machine' ; db 'The current code pointer (in the SI register)' ; db 'is saved - pushed onto the return stack [es:di] and the address ; db 'of the virtual proc to execute is loaded into SI. ' ; dw $-fcall.doc fcall: dw umixmult.x db 'fcall', 5 fcall.x: lodsw mov [es:di], si add di, 2 mov si, ax ; adjust the si code pointer jmp exec.nextopcode ; We can also write "execute" as well which will work ; with opcodes by using a temporary compile buffer ; in the dictionary or just doing pcall. see word "exec" pcall.doc: ; db ' ( xt -- ) ' ; db ' Call a procedure using the top element on ' ; db ' the data stack as the execution address. This ' ; db ' allows the implementation of function pointers' ; db ' In standard forths this is called "execute". But ' ; standard forth does not distinguish between opcodes and procs ; so execute will do both. ; dw $-pcall.doc pcall: dw fcall.x db 'pcall', 5 ; or call it exec/ex/execute pcall.x: mov [es:di], si ; save ip to return stack add di, 2 mov si, dx ; get proc exec address from stack pop dx jmp exec.nextopcode exit.doc: ; db 'exit a virtual procedure by restoring si ' ; db 'code pointer' ; dw $-exit.doc exit: dw pcall.x db 'exit', 4 exit.x: sub di, 2 mov si, [es:di] ; restore si from rstack jmp exec.nextopcode dup.doc: ; db 'Duplicates the top item on the stack.' ; dw $-dup.doc dup: dw exit.x ; link to previous word db 'dup', 3 ; strings are 'counted' dup.x: push dx ; dup TOS jmp exec.nextopcode drop.doc: ; db 'removes the top item on the stack.' ; dw $-drop.doc drop: dw dup.x ; link to previous word db 'drop', 4 ; name with reverse count drop.x: pop dx ; remove top element of stack jmp exec.nextopcode swap.doc: ; db 'swaps the top 2 items on the stack.' ; dw $-swap.doc swap: dw drop.x ; link to previous word db 'swap', 4 swap.x: pop ax ; get top stack item push dx ; put them back on in reverse order mov dx, ax ; tos=dx jmp exec.nextopcode over.doc: ; db ' ( n1 n2 -- n1 n2 n1 ) ' ; db ' Puts a copy of 2nd stack item on top of stack. ' ; db ' dont use this, will probably remove. ' ; dw $-over.doc over: dw swap.x ; link to previous word db 'over', 4 over.x: pop ax ; get NOS (next-on-stack) stack item push ax ; push dx ; mov dx, ax ; add copy of 2nd item on top of stack jmp exec.nextopcode twodup.doc: ; db ' ( n1 n2 -- n1 n2 n1 n2 ) ' ; db ' copies 2 stack items onto stack ' ; dw $-twodup.doc twodup: dw over.x db '2dup', 4 twodup.x: pop ax ; get NOS next stack item push ax ; push dx ; push ax ; n1 n2 n1 n2 jmp exec.nextopcode flags.doc: ; db ' ( -- n ) ' ; db ' push flag register onto the stack ' ; db ' execution flags such as carry overflow negate etc ' ; db ' are pushed onto the stack ' ; dw $-flags.doc flags: dw twodup.x db 'flags', 5 flags.x: push dx ; save NOS on stack pushf pop dx ; get flags into TOS (dx) jmp exec.nextopcode depth.doc: ; db ' ( -- n ) ' ; db ' Puts on the stack the number of stack items ' ; db ' before this word was executed ' ; dw $-depth.doc depth: dw flags.x db 'depth', 5 depth.x: push dx mov bx, sp mov dx, 4096 ; 4K stack (but could change!) sub dx, bx ; shr dx, 1 ; div by 2 (2 byte stack cell) ;causing problems ??? ;dec ax ; the exec.x call doesnt count jmp exec.nextopcode rdepth.doc: ; db ' ( -- n ) ' ; db ' Puts on the stack the number of stack items ' ; db ' on the return stack before this word ' ; db ' was executed ' ; dw $-rdepth.doc rdepth: dw depth.x db 'rdepth', 6 rdepth.x: push dx mov dx, di shl dx, 1 jmp exec.nextopcode ron.doc: ; db '( S: n -- )( R: -- n ) ' ; db ' put the top item of the data stack onto the return stack.' ; dw $-ron.doc ron: dw rdepth.x db '>r', 2 ron.x: mov ax, dx ; value to store at address (tos=dx) stosw ; [es:di] := ax, di+2 pop dx jmp exec.nextopcode roff.doc: ; db '( S: -- n)( R: n -- ) ' ; db ' put the top item of the return stack onto the data stack.' ; dw $-roff.doc roff: dw ron.x db 'r>', 2 roff.x: push dx ; push new nos on stack sub di, 2 ; mov dx, [es:di] ; get top item off return stack jmp exec.nextopcode store.doc: ; db '( w adr -- ) ' ; db ' place 2 byte value w at address "adr" ' ; dw $-store.doc store: dw roff.x db '!', 1 store.x: mov bx, dx ; pointer to address pop ax ; value to store at address mov [bx], ax ; 2 byte is stored pop dx jmp exec.nextopcode storeplus.doc: ; db '( w adr -- adr+2 ) ' ; dw $-storeplus.doc storeplus: dw store.x ; link to previous word db '!+', 2 storeplus.x: mov bx, dx ; pointer to address pop ax ; value to store at address mov [bx], ax ; 2 byte value is stored inc dx ; advance address and put on stack inc dx ; advance address and put on stack jmp exec.nextopcode fetch.doc: ; db '( adr -- n ) ' ; db ' Replace the top element of the stack with the ' ; db ' value of the 16bites at the given memory address ' ; dw $-fetch.doc fetch: dw storeplus.x ; link to previous word db '@', 1 fetch.x: mov bx, dx ; address in tos mov dx, word [bx] jmp exec.nextopcode fetchplus.doc: ; db '( adr -- adr+2 n ) ' ; db ' Replace the top element of the stack with the ' ; db ' value of the 16bites at the given memory address ' ; db ' and increment the address by 2 bytes. ' ; dw $-fetchplus.doc fetchplus: dw fetch.x ; link to previous word db '@+', 2 fetchplus.x: mov bx, dx mov dx, word [bx] ; value on top of stack add bx, 2 ; increment address by 1 word (2 bytes) push bx ; save address on stack jmp exec.nextopcode cstore.doc: ; db '( n adr -- ) store the byte value n at address adr.' ; db ' eg: 10 myvar ! ' ; db ' puts the value 10 at the address specified by "myvar" ' ; db ' The address is the top value on the stack. ' ; dw $-cstore.doc cstore: dw fetchplus.x ; link to previous word db 'c!', 2 cstore.x: mov bx, dx ; pointer to address pop ax ; value to store at address mov [bx], al ; only the low value byte is stored pop dx jmp exec.nextopcode cstoreplus.doc: ; db '( n adr -- adr+1 ) store the byte value n at address adr.' ; db ' And increment the address ' ; dw $-cstoreplus.doc cstoreplus: dw cstore.x ; link to previous word db 'c!+', 3 cstoreplus.x: mov bx, dx ; pointer to address pop ax ; value to store at address mov [bx], al ; only the low value byte is stored inc dx ; advance address and put on stack (tos=dx) jmp exec.nextopcode cfetch.doc: ; db '( adr -- n ) Replace the top element of the stack with the value ' ; db ' of the byte at the given memory address.' ; db ' eg: myvar @ . ' ; db ' displays the value at the address given by "myvar" ' ; dw $-cfetch.doc cfetch: dw cstoreplus.x ; link to previous word db 'c@', 2 cfetch.x: mov bx, dx ; tos=dx xor dx, dx ; set dx := 0 mov al, byte [bx] cbw ; convert signed byte to signed word ax mov dx, ax ; put literal value on stack (tos=dx) jmp exec.nextopcode ; need to sign extend !! cfetchplus.doc: ; db '( adr -- adr+1 n ) ' ; db ' Replace the top element of the stack with the value ' ; db ' of the byte at the given memory address and increment the ' ; db ' address . This is exactly the same as "count"' ; dw $-fetchplus.doc cfetchplus: dw cfetch.x ; link to previous word db 'c@+', 3 cfetchplus.x: mov bx, dx xor dx, dx ; set dx := 0 mov al, byte [bx] cbw ; convert signed byte to signed word ax mov dx, ax ; put literal value on stack (tos=dx) inc bx ; increment address by 1 push bx ; save new address on stack jmp exec.nextopcode equals.doc: ; db ' ( n1 n2 -- flag ) ' ; db 'Puts -1 (true) on the stack if n1==n2 ' ; db 'otherwise puts zero (false) on the stack. ' ; dw $-equals.doc equals: dw cfetchplus.x ; link to previous word db '=', 1 equals.x: pop bx ; 2nd stack item cmp dx, bx ; if tos==nos je .true .false: mov dx, 0 jmp .exit .true: mov dx, -1 .exit: jmp exec.nextopcode notequals.doc: ; db ' ( n1 n2 -- flag ) ' ; db 'Puts 0 (false) on the stack if n1==n2 ' ; db 'otherwise puts -1 (true) on the data stack' ; dw $-notequals.doc notequals: dw equals.x ; link to previous word db '<>', 2 notequals.x: pop bx ; 2nd stack item cmp dx, bx jne .true .false: mov dx, 0 jmp .exit .true: mov dx, -1 .exit: jmp exec.nextopcode lessthan.doc: ; db ' ( n1 n2 -- flag ) ' ; db 'Puts 0 (false) on the stack if n1 al ; if the character is printable (not cr/nl/tab/ff etc) ; then print it with ah=0x09, otherwise print it with ; ah=0x0E cmp al, 7 jb .printable ; jb (jump if below) is an unsigned comparison cmp al, 13 ja .printable ; ja (jump if above) is an unsigned comparison mov ah, 0x0E ; bios teletype function int 10h pop dx ; tos in dx jmp exec.nextopcode .printable: mov bl, [bg.d] ; high 4 bits are background colour shl bl, 4 ; put the number (0-15) in high bits mov dl, [fg.d] ; low 4 bits are foreground colour or bl, dl ; ;mov bl, 0x2F ; just for debug. ; I dont understand this page number parameter... mov bh, 0 ; assume we are working in the first page mov ah, 0x09 ; the 'function' number for colour print mov cx, 1 ; print the character once int 10h ; increment the cursor position mov ah, 03h ; get cursor position into dx int 10h mov ah, 02h ; set cursor position function inc dl ; increment the column position int 10h pop dx ; tos in dx jmp exec.nextopcode ; The old version of emit using function ah=0x0E int 0x10 ; The main disadvantage is that background colours dont seem to ; work with this teletype function. emito.doc: ; db 'removes and displays top item on stack as an ascii character.' ; db 'I suppose the character is in the low byte of the stack item...' ; dw $-emit.doc emito: dw litw.x db 'emit', 4 emito.x: mov ax, dx ; char in dl (dx is TOS) -> al ; these background colours arent working in qemu (?) mov bl, [bg.d] ; high 4 bits are background colour shl bl, 4 ; put the number (0-15) in high bits mov dl, [fg.d] ; low 4 bits are foreground colour or bl, dl ; mov ah, 0x0E ; bios teletype function int 10h pop dx ; tos in dx jmp exec.nextopcode ; This code uses function ah=0x09 instead of ah=0x0E ; to print a character. The cursor must also be advanced. ; Another option is to write directly to video memory to ; print characters %if 0 mov bh, 0 ; assume we are working in the first page mov ah, 09h ; the 'function' number for colour print mov cx, 1 ; print the character once int 10h ; do it with a bios interrupt mov ah, 03h ; get cursor position into dx int 10h mov ah, 02h ; set cursor position function inc dl ; increment the column position int 10h %endif ; key? can also use 16h ah=01h akey.doc: ; db 'Flag if a key is available' ; dw $-key.doc akey: dw emit.x ; link to prev db 'key?', 4 ; reverse counted string akey.x: push dx ; make tos into nos mov ah, 1 ; check if key available int 16h ; al := ... jz .nokey mov dx, 1 ; put flag on stack jmp exec.nextopcode .nokey: mov dx, 0 jmp exec.nextopcode ; key? can also use 16h ah=01h key.doc: ; db 'Get one keystroke from user and place on stack' ; db 'The key is represented as an ascii code in the low byte ' ; db 'of the stack item.' ; dw $-key.doc key: dw akey.x ; link to prev db 'key', 3 ; reverse counted string key.x: push dx ; make tos into nos mov ah, 0 ; wait for keypress bios function int 16h ; ah := asci code and al := scan code mov ah, 0 ; set ah = 0 mov dx, ax ; save asci code onto stack (tos=dx), high byte zero jmp exec.nextopcode ekey.doc: ; db ' ( -- event flag ) ' ; db 'Get one keyboard event and place on stack' ; db 'This includes arrow keys etc. The flag indicates if the ' ; db 'code represents an extended character (eg arrow key) ' ; db 'or just an ordinary asci character ' ; dw $-ekey.doc ekey: dw key.x ; link to prev db 'ekey', 4 ; reverse counted string ekey.x: push dx mov ah, 0 ; wait for keypress bios function int 16h ; ah := asci code and al := scan code cmp al, 0 ; is extended char (AL == 0) ? je .extended ; wait for next key if not -> mov ah, 0 ; set ah = 0 push ax ; save asci code onto stack, high byte zero mov dx, 0 ; false flag jmp exec.nextopcode .extended: mov al, ah ; set ah = al xor ah, ah ; set high byte to zero push ax ; save event code onto stack, high byte zero mov dx, 1 ; true flag (is extended char) jmp exec.nextopcode getxy.doc: ; db ' ( -- x y ) ; db ' Return the x and y position of the cursor. ' ; dw $-getxy.doc getxy: dw ekey.x ; link to previous db 'getxy', 5 ; reverse counted string getxy.x: ; dl=x/col dh=y/row push dx ; make tos into nos mov ah, 03h ; bios function: get cursor position into dx int 10h ; invoke bios mov bx, dx ; dl=x, dh=y mov dl, dh and dx, 0x00FF and bx, 0x00FF push bx jmp exec.nextopcode atxy.doc: ; db ' ( x y -- ) ; db ' set the x and y position of the cursor. ' ; dw $-setxy.doc atxy: dw getxy.x db 'atxy', 4 atxy.x: ; dl=col dh=row mov dh, dl pop bx mov dl, bl mov ah, 02h ; bios function: set cursor position specified in dx int 10h ; invoke bios pop dx jmp exec.nextopcode ljump.doc: ; db 'jumps to a relative virtual instruction.' ; db ' The jump is given in the next 2 bytes' ; dw $-ljump.doc ljump: dw atxy.x ; link to prev db 'ljump', 5 ; reverse count ljump.x: xor ax, ax ; set ax := 0 lodsw ; al := [si]; si=si+2 get relative jump target into AL sub si, 3 ; realign si to LJUMP instruction (target is 2 bytes) add si, ax ; adjust the si code pointer by offset jmp exec.nextopcode jump.doc: ; db 'jumps to a relative virtual instruction.' ; db ' The relative jump is given in the next byte.' ; db ' eg: JUMP, -2, jumps back 2 instructions in the bytecode' ; db ' eg: LIT, '*', EMIT, JUMP, -3, ' ; db ' prints a never-ending list of asterixes ' ; dw $-jump.doc jump: dw ljump.x ; link to prev db 'jump', 4 ; reverse count jump.x: ; jumps can be handled in the exec routine ; handle jumps by modifying virtual ip (in this case SI) xor ax, ax ; set ax := 0 lodsb ; al := [si]++ get relative jump target into AL cbw ; convert signed byte al to signed word ax (neg offset) sub si, 2 ; realign si to JUMP instruction, add si, ax ; adjust the si code pointer by jump offset ; do we need to decrement si ?? yes, more logical jmp exec.nextopcode jumpz.doc: ; db ' ( n -- ) ; db 'jumps to a relative virtual instruction if top ' ; db 'stack element is zero. The flag value is removed ' ; db 'from the stack ; db ' The relative jump is given in the next byte.' ; db ' eg: JUMPZ, -2, jumps back 2 instructions in the bytecode' ; db ' eg: KEY, DUP, EMIT, LIT, '0', MINUS, JUMPNZ, -6 ' ; db ' allows the user to type until zero is pressed. ' ; dw $-jump.doc ; handle jumps by modifying virtual ip (in this case SI) jumpz: dw jump.x ; link to prev db 'jumpz', 5 ; reverse count jumpz.x: xor ax, ax ; set ax := 0 lodsb ; al := [si]++ get relative jump target into AL ; check stack for zero, if not continue with next instruction cmp dx, 0 ; if dx != 0 continue (tos==dx) jne .exit cbw ; convert signed byte al to signed word ax (neg offset) sub si, 2 ; realign si to JUMP instruction, add si, ax ; adjust the si code pointer by jump offset .exit: pop dx jmp exec.nextopcode ; should jumps take top stack element off ? yes jumpnz.doc: ; db 'jumps to a relative virtual instruction if top stack element ' ; db ' is not zero. ; db ' The relative jump is given in the next byte.' ; db ' eg: JUMPNZ, -2, jumps back 2 instructions in the bytecode' ; db ' eg: KEY, DUP, EMIT, LIT, 'q', MINUS, JUMPNZ, -6 ' ; db ' allows the user to type until "q" is pressed. ' ; dw $-jumpnz.doc jumpnz: dw jumpz.x ; link to prev db 'jumpnz', 6 ; reverse count jumpnz.x: ; handle jumps by modifying virtual ip (in this case SI) xor ax, ax ; set ax := 0 lodsb ; al := [si]++ get relative jump target into AL ; check stack for zero, if so continue with next ; instruction (dont jump) cmp dx, 0 ; if bx != 0 continue je .exit ; the only difference with jumpz ! cbw ; convert signed byte al to signed word ax (neg offset) sub si, 2 ; realign si to JUMP instruction, add si, ax ; adjust the si code pointer by jump offset .exit: pop dx jmp exec.nextopcode rloop.doc: ; db ' ( R: n -- n-1 ) ' ; db ' Decrements loop counter on return stack and jumps to ' ; db ' target if counter > 0 ' ; db ' like the x86 loop instruction this is a pre-decrement ' ; db ' so a loop counter of 2 will loop twice. The disadvantage ' ; db ' is that a loop counter of 0 will loop 2^16 times. ' ; dw $-rloop.doc rloop: dw jumpnz.x ; link to prev db 'rloop', 5 ; reverse count rloop.x: ; handle loops by modifying virtual ip (in this case SI) xor ax, ax ; set ax := 0 lodsb ; al := [si]++ get relative loop target into AL ; check return stack for zero, if so continue with next ; instruction (dont jump/loop) mov bx, [es:di-2] ; get top return stack item into bx dec bx ; decrement the loop counter on the return stack cmp bx, 0 ; if bx != 0 continue mov [es:di-2], bx ; update the counter je .exit ; the only difference with jumpz ! cbw ; convert signed byte al to signed word ax (neg offset) sub si, 2 ; realign si to JUMP instruction, add si, ax ; adjust the si code pointer by jump offset .exit: jmp exec.nextopcode ; sectors/track and sides are set by bootup code int 13h, ah=8 ; SectorsPerTrack: dw 18 ; standard floppy config ; Sides: dw 2 ; floppies only have one 'platter' read.doc: ; db ' ( 1st-sector n addr -- flag=T/F ) ; db ' reads n sectors from disk starting at sector to memory addr ' ; db ' returns 0 on failure, 1 on success. ' ; dw $-read.doc read: dw rloop.x db 'read', 4 read.x: ; 1st-sect n address mov fs, dx ; destination memory address in this segment .reset: ; Reset the virtual floppy drive (usb) mov ax, 0 ; mov dl, byte [drive.d] ;boot drive number (eg for usb 128) int 13h ; jc .reset ; read error => reset again .read: ; need to save es since rstack points with it!! mov [saven.es], es mov ax, ds ; set es:=ds because we read into this segment mov es, ax ; es:bx determines where data loaded to pop gs ; how many sectors ( -> AL) pop ax ; start sector ; -- thanks to mike gonta for this code .logical: ; Will there be issues with multi-track reads? ; Also, sectors start at one not zero !! ; So sector 1 is the boot sector on disk. ; Calculate track (cylinder), head and sector (chs) settings ; for the int 13h (ah=2) read disk function ; IN: logical sector in AX, OUT: correct registers for int 13h ; cl := start sector ; ch := track (or cylinder) ; dh := head (or side) ; dl := drive or boot device ; ah := 2 (Int 13h read sectors from disk function) ; al := how many sectors to read ; es:bx := destination address in memory ; ;push bx ;push ax ; ax has how many sectors to read mov bx, ax ; Save logical sector mov dx, 0 div word [sectorspertrack.d] ; First the sector add dl, 01h ; Physical sectors start at 1 mov cl, dl ; Sectors belong in CL for int 13h mov ax, bx mov dx, 0 ; Now calculate the head div word [sectorspertrack.d] mov dx, 0 div word [sides.d] mov dh, dl ; Head/side mov ch, al ; Track ;pop ax ;pop bx mov dl, byte [drive.d] ; Set correct device mov bx, fs ; es:bx is destination address in ram for read mov ax, gs ; ax (al) := how many sectors to read mov ah, 2 ; int 13H function ah:2 "Load disk data to ES:BX" int 13h ; Read! jc .readerror ; ERROR => Try again ;*** restore es since rstack points with it!! mov es, [saven.es] mov dx, 1 ; return true flag for success jmp exec.nextopcode .readerror: ;*** restore es since rstack points with it!! mov es, [saven.es] mov dx, 0 ; return false flag for read error jmp exec.nextopcode saven.es: dw 0 ; this has the potential to 'brick' a computer so we need to ; get it right before doing it. write.doc: ; db ' ( first-sector n addr -- flag=T/F/2 ) ; db ' write sectors to disk ' ; dw $-write.doc write: dw read.x db 'write', 5 write.x: ; to do: test, very, very, carefully ; 1st-sect n address mov fs, dx ; source memory address in this segment .reset: ; Reset the virtual floppy drive (usb) mov ax, 0 ; mov dl, byte [drive.d] ;boot drive number (eg for usb 128) int 13h ; jc .reset ; read error => reset again .testread: ; below is a sanity check read to make sure we are going ; to write to the correct disk. ; cl := (1) start sector, in this case boot sector ; ch := (0) track (or cylinder) number ; dh := (0) head (or side) ; dl := drive or boot device 0-3=diskette; 80H-81H=hard disk ; ah := 3 (Int 13h write sectors to disk function) ; al := (1) how many sectors to read ; es:bx := where to read data. In this case a testbuffer ; which is 'first' + 512 bytes mov [saven.es], es mov ax, ds ; at the moment 64K segment mov es, ax ; es:bx determines where data is read from mov dh, 0 ; first side mov dl, byte [drive.d] ; Set correct device mov bx, fs ; es:bx is destination address in ram for read add bx, 1024 ; read to next block mov ch, 0 ; first track/cylinder mov cl, 1 ; read boot sector (1) mov ax, 1 ; ax (al) := how many sectors to read mov ah, 2 ; int 13H function ah:2 "read data from disk from ES:BX" int 13h ; read it! jc .readerror ; if error should try again, but we dont... mov dx, word [es:bx+8] ; address of magic number ; if the magic number (pi*10000) is not there then this ; maybe the wrong disk, so dont write to it! cmp dx, 31415 jne .notpi ;mov es, [saven.es] ;jmp exec.nextopcode .write: ;*** need to save es since rstack points with it!! ;mov [saven.es], es mov ax, ds ; at the moment 64K segment mov es, ax ; es:bx determines where data is written from pop gs ; how many sectors ( will go in AL) pop ax ; logical start sector .logical: ; Will there be issues with multi-track write? probably ; So sector 1 is the boot sector on disk. ; Calculate track (cylinder), head and sector (chs) settings ; for the int 13h (ah=3) write to disk function ; IN: logical sector in AX, OUT: correct registers for int 13h, ah=3 ; cl := start sector (1-n) ; ch := track (or cylinder) number (0-n) ; dh := head (or side) ; dl := drive or boot device 0-3=diskette; 80H-81H=hard disk ; ah := 3 (Int 13h write sectors to disk function) ; al := how many sectors to read ; es:bx := source address in memory of data to write ; ; ax has how many sectors to write mov bx, ax ; Save logical sector mov dx, 0 div word [sectorspertrack.d] ; First the sector add dl, 01h ; Physical sectors start at 1 mov cl, dl ; Sectors belong in CL for int 13h mov ax, bx mov dx, 0 ; Now calculate the head div word [sectorspertrack.d] mov dx, 0 div word [sides.d] mov dh, dl ; Head/side mov ch, al ; Track ; setting the drive correctly is pretty ; important, see sanity check above mov dl, byte [drive.d] ; Set correct device mov bx, fs ; es:bx is destination address in ram for write mov ax, gs ; ax (al) := how many sectors to read mov ah, 3 ; int 13H function ah:3 "write data to disk from ES:BX" int 13h ; Write it! jc .writeerror ; if error should try again, but we dont... ;*** restore es since rstack points with it!! mov es, [saven.es] mov dx, 1 ; return true flag for success jmp exec.nextopcode .readerror: .writeerror: ;*** restore es since rstack points with it!! mov es, [saven.es] mov dx, 0 ; return false flag for read error jmp exec.nextopcode .notpi: mov es, [saven.es] mov dx, -1 ; notpi flag jmp exec.nextopcode ; This opcode and vid.x are obviously not going to be ; available on all hardware. So we need to think about ; how to configure plugable opcodes. Eg: what if a device ; has a gyroscope. We want opcodes to read from that gyroscope ; fg.doc: ; db ' ( n -- ) ' ; db ' set foreground colour for emit' ; dw $-fg.doc fg: dw write.x db 'fg', 2 fg.x: mov [fg.d], dl ; pop dx jmp exec.nextopcode fg.d: db 5 ; colour cyan ; not working bg.doc: ; db ' ( n -- ) ' ; db ' set the background colour for emit' ; dw $-bg.doc bg: dw fg.x db 'bg', 2 bg.x: mov [bg.d], dl ; pop dx jmp exec.nextopcode ;ret bg.d: db 0 ; cls.doc: ; db ' ( -- ) ' ; db ' clear screen' ; dw $-cls.doc cls: dw bg.x db 'cls', 3 cls.x: push dx mov ah, 06h ; ah=function number for int10 (06) mov al, 00h ; al=number of lines to scroll (00=clear screen) ;mov bx, 700h ; bh=color attribute for new lines (grey) mov bx, 00h ; bh=color attribute for new lines xor cx, cx ; ch=upper left hand line number of window (dec) ; cl=upper left hand column number of window (dec) mov dx, 184fh ; dh=low right hand line number of window (dec) ; dl=low right hand column number of window (dec) int 10h pop dx jmp exec.nextopcode cursor.doc: ; db ' ( n m -- / display cursor block from row m to row n, n>m *) ' ; db ' sets the text screen cursor shape, with 0 0=hidden' ; dw $-cursor.doc cursor: dw cls.x db 'cursor', 6 cursor.x: ; CH = Scan Row Start, CL = Scan Row End ; CX=0607h normal underline cursor (start at row 6 end row 7) ; CX=0007h full-block ; CX=0706h start=7>end=6 This may hide the cursor! ; Or set bit 5 to hide cursor ; CX=2607h invisible cursor (bit 5 set) ; push dx mov ah, 01h ; int10 set cursor shape function xor cx, cx ; pop cx ; cl <- row end (NOS) mov ch, dl ; top of stack into ch int 10h pop dx ; 3rd-on-stack into DX (new tos) jmp exec.nextopcode vid.doc: ; db ' ( n -- ) ' ; db ' set video mode to n' ; db ' on x86 try 13h mode' ; dw $-vid.doc vid: dw cursor.x db 'vid', 3 vid.x: mov ax, dx ; get video mode mov ah, 0 ; ah=0 set video mode function, al=mode int 10h pop dx jmp exec.nextopcode ; pix is called "plot" in some old forths. plot.doc: ; db ' ( x y -- / show 1 pixel at [x,y] with colour from FG *) ' ; dw $-plot.doc plot: dw vid.x db 'plot', 4 plot.x: ; using interrupts to draw pixels is very slow but ok ; for playing around pop cx ; get x-coordinate ; y-coordinate in dx ; mov al, 15 ; white mov al, [fg.d] ; foreground colour set by FG mov ah, 0ch ; put pixel int 10h ; draw pixel pop dx jmp exec.nextopcode glyph.doc: ; db ' ( a -- ) ' ; db ' display a colour glyph at pixel position xy' ; dw $-glyph.doc glyph: dw plot.x db 'glyph', 5 glyph.x: jmp exec.nextopcode ; this may be useful for timing code ; clock updates at 1193180/65536 (about 18.2) ticks per second. ; counts per second 18 ; counts per minute 1092 ; counts per hour 65543 ; counts per day 1573040 ; clock incremented approx every 55ms clock.doc: ; db ' ( -- D ) ' ; db ' number of clock ticks since midnight ' ; dw $-clock.doc clock: dw glyph.x db 'clock', 5 clock.x: push dx mov ah, 00h ; interrupt to get clock ticks since midnight int 1Ah ; cx:dx now holds number of clock ticks since midnight push dx ; low byte on lower stack position mov dx, cx ; high byte on higher stack position jmp exec.nextopcode ; There are "issues" here. It is not always possible to ; set format for rtc time, so need to check format from status ; register B and convert if necessary. Also, should check for ; 2 values the same in a loop, so overcome updating problems rtc.doc: ; db ' ( -- secs mins hours days months years ) ' ; db 'return 6 values on stack representing real time and date. ' ; db 'called time&date in standard forths. ' ; dw $-rtc.doc rtc: dw clock.x db 'rtc', 3 rtc.x: push dx ; save top of stack xor ax, ax ; set ah, al == 0 ; status register B controls format of rtc values but ; cant always be set cli mov al, 0x0B ; try to set date format out 0x70, al ; address reg ; set bit 1=24hour, bit 2=binary/bcd mov al, 6 ; set 2 low bits on date register B out 0x71, al ; set register sti .updating: ; not used at the moment mov al, 0x0A ; check if an update in progress out 0x70, al ; address reg in al, 0x71 ; get data from cmos data reg test al, 0x80 ; is high bit set? ; in theory we are not supposed to read the real time clock ; data if an update is in progress, but we wont worry at the ; moment about this cli ; disable interrupts mov al, 0x00 ; select seconds out 0x70, al ; address reg in al, 0x71 ; get seconds data from data reg sti push ax cli mov al, 0x02 ; select minutes out 0x70, al ; address rtc minute register in al, 0x71 ; get data from cmos data reg sti push ax cli mov al, 0x04 ; select Hour out 0x70, al ; address rtc minute register in al, 0x71 ; get hour data from cmos data reg sti push ax mov al, 0x07 ; Day of month out 0x70, al ; cmos select reg in al, 0x71 ; cmos data reg push ax mov al, 0x08 ; Month out 0x70, al ; cmos select reg in al, 0x71 ; cmos data reg push ax mov al, 0x09 ; Year out 0x70, al ; cmos select reg in al, 0x71 ; cmos data reg mov dx, ax ; tos=dx jmp exec.nextopcode noop.doc: ; db 'Does nothing. For some reason most machines ' ; db 'include this instruction. Also it is a good ' ; db 'end marker for the opcodes ' ; dw $-noop.doc noop: dw rtc.x db 'nop', 3 noop.x: jmp exec.nextopcode ; ******************************* ; end of opcodes ; ******************************* ; ************ ; some immediate words ; ************ ; namespace table here?? hello.doc: ; db ' ( -- ) ; db ' Just testing immediate procs ' hello: dw noop.x db 'hello', IMMEDIATE | 5 hello.p: db LIT, '!', EMIT db LIT, 'h', EMIT db LIT, 'i', EMIT db EXIT literal.doc: ; db ' (comp: n -- )(run: -- n) ; db ' Push the TOS onto the data stack at run-time ' ; db ' This advances compile point by 3 bytes ' literal: dw noop.x db 'literal', IMMEDIATE | 7 literal.p: db LIT, LITW ; n op=LITW db FCALL dw ccomma.p ; n /compile LITW opcode at HERE db FCALL ; tos is 2bytes so use , not c, dw comma.p ; tos will be pushed onto stack at runtime db EXIT ; create hangs on no input, but wparse doesnt. ; important word!! probably used by all defining words ; including colon : and VAR & CONSTANT ; create is not "immediate" funnily enough but colon is. ; there is a bug with defining words. actually we need a (create) ; which is this code below, and then an immediate create which ; sets a defining bit. create.doc: ; db ' ( -- ) ; db ' create a new word header in the dictionary ' ; db ' CREATE also compiles code to push the address of ' ; db ' the parameter field onto the stack at runtime. ' ; db ' As often pointed out, CREATE does not allocate any space ' ; db ' for the parameter field. The coder can do that with ALLOT or ' ; db ' C, or , etc .' ; db ' In this x86 implementation, the start of the parameter field ' ; db ' is just the next available byte in the dictionary. ' create: dw literal.p db 'create', 6 create.p: ; here>code does lots of important stuff, see above. ; such as executing the anon buffer db FCALL dw heretocode.p ; now compile the name to the dictionary. Use code in colon ; to see how. ; before any new words have been compiled with colon : ; then "last" points to "last" ! After new words have been ; added then "last" will point to the last word added ; (in the current namespace ...) db FCALL dw last.p ; /get pointer to last word in dictionary ; or last word in "current" definition word ; list db FETCH ;*** insert link to previous last word in dict at HERE db FCALL dw comma.p ;*** get the name & length of the new word db FCALL dw wparse.p ; a n ;*** if wparse returns 0 then no name, only whitespace db DUP ; a n n db JUMPZ, .noname-$ ; a n db DUP, RON ; a n r: n ; compile string to current compile position db FCALL dw scompile.p ; r: n db ROFF ; n ; compile count|control byte after name db FCALL dw ccomma.p ; set last pointer to new word execution address db FCALL dw here.p ; adr /xt for new word db FCALL ; change this to FCALL current.p (current definition wordlist) dw last.p ; adr last /pointer to last word db STORE ; now compile some code that puts the parameter field address ; on the stack db FCALL dw here.p ; adr / address of next byte in dict (current xt) db LIT, 4, PLUS ; adr+3 / adjust for LITW, , EXIT == 4 bytes db LIT, LITW ; adr+3 op=LITW db FCALL dw ccomma.p ; adr+3 / compile LITW opcode db FCALL ; address is 2bytes so use , not c, dw comma.p ; /compile address of next byte in dictionary db LIT, EXIT ; op=EXIT db FCALL dw ccomma.p ; / compile EXIT opcode db FCALL dw codetohere.p ; set >code to here db EXIT .noname: db DROP, DROP ; clear data stack db LIT, '?', EMIT ; db LIT, '?', EMIT ; db EXIT callcomma.doc: ; db ' ( xt -- ) ; db ' compile an fcall to xt ' callcomma: dw create.p db 'call,', IMMEDIATE | 5 callcomma.p: db LIT, FCALL ; xt op=fcall db FCALL dw ccomma.p ; xt db FCALL dw comma.p db EXIT ; This can be tested with : d drop ; : var go ; find d (does>)' ; should reset the code field of "go" to behaviour of "d" ; all defining words need to be immediate, so 'create' could ; just do that automatically rundoes.doc: ; db ' ( -- ) ; db ' perform run-time behaviour of does> ' rundoes: dw callcomma.p db '(does>)', 7 rundoes.p: ; xt /xt -> code after does> in defining word ;db EXIT ; when (does>) runs then 'here' should be pointing just after ; the parameter field of the new word. That is, just after any ; data space that has been allotted with 'allot' or ',' etc db FCALL dw here.p ; xt here db DUP ; xt H H db FCALL dw last.p ; xt H H L* db FETCH ; xt H H last db DUP ; xt H H L L ; set new compile point to last xt (word just created) db FCALL dw ishere.p ; xt H H L ; compile jump opcode db LIT, JUMP ; xt H H L op=jump db FCALL dw ccomma.p ; xt H H L ; calculate jump offset. The jump must jump over the ; parameter field of the defined word (this field is ; allocated with 'allot' or , or c, etc) db MINUS ; xt H (H-L) ; compile offset db FCALL dw ccomma.p ; xt H ; reset "here" to end of new word (after parameter field) db FCALL dw ishere.p ; xt ; compile code to push parameter field of new word onto stack ; at the run-time of the new word its param field goes onto ; the stack, so that the code after does> can use it. db FCALL dw last.p ; xt last* db FETCH ; xt last db LIT, 4, PLUS ; xt last+4 db FCALL dw literal.p ; xt ; compile call to xt (code just after does> in defining word) db FCALL dw callcomma.p ; ; the code below is just ; semicolon ; could write ; db FCALL ; dw semicolon.p ; compile an exit for the new word being defined db LIT, EXIT ; op=exit db FCALL dw ccomma.p ; update the dictionary compile point and reset compile ; point to anon buffer (these are tasks that semicolon normally ; does) db FCALL dw codetohere.p ; do code>here db FCALL dw heretoanon.p ; db EXIT ; there are 3 "times" here. Compile-time for the defining word ; run-time for defining word (which is also compile-time for ; the defined word). And run-time for the defined word. ; These three "times" can make thinking about defining words ; tricky does.doc: ; db ' ( -- ) ; does: dw rundoes.p db 'does>', IMMEDIATE | 5 does.p: ; compile current 'here' (compile point) so that it will ; be pushed onto stack at run-time of defining word ; (which is compile-time of defined word) db FCALL dw here.p ; H ; adjust the literal to account for the code following ; which will be compiled db LIT, 7, PLUS ; H+7 db FCALL dw literal.p ; ; compile "fcall (does>)" ; but this is the same as call, db LIT, FCALL ; H op=fcall db FCALL dw ccomma.p ; H db LITW dw rundoes.p ; xt db FCALL dw comma.p ; compile an exit (for does> at run-time) db LIT, EXIT ; op=exit db FCALL dw ccomma.p db EXIT resetp.doc: ; db ' ( -- ) ; db ' Resets >code and here to just after the wordname count byte' resetp: dw does.p db 'reset', 5 resetp.p: ; After create HERE and >CODE @ should both be pointing just after ; code to push parameter field onto stack, so we need to ; repoint these back to the xt (just after the name count byte) db FCALL dw tocode.p ; >code db DUP ; >code >code db FETCH, LIT, 4 ; >code code* 4 db MINUS ; >code code*-4 db SWAP ; code*-4 >code db STORE ; db FCALL dw heretocode.p ; set here to point to >code db EXIT ; things to do in CREATE (called by : COLON) ; Set HERE to next code space with HERE>CODE ; create a header. first link back using LAST ; and set LAST to new word ; then compile name, with S, ; compile count, then just exit and let IN, handle the rest ; (which is actually calling : COLON anyway). ; In semicolon: ; when ; compile "exit" set >code to here ; colon.doc: ; db ' ( -- ) ; db ' Creates a new word in the dictionary.' ; db ' The only difference with the CREATE word is that ' ; db ' no code is appended after the word name and count ' colon: dw resetp.p db ':', IMMEDIATE | 1 colon.p: ; HERE>CODE in CREATE will execute stuff in the ANON buffer ; (as with all defining words which use create.) db FCALL dw create.p db FCALL dw resetp.p db EXIT ;.noname: ; db DROP, DROP ; clear data stack ; db LIT, '?', EMIT ; ; db LIT, '?', EMIT ; ; db EXIT semicolon.doc: ; db ' ( -- ) semicolon: dw colon.p db ';', IMMEDIATE | 1 semicolon.p: ; compile an exit ; set >code to here ; set ishere to anon buffer db LIT, EXIT db FCALL dw ccomma.p ; compile opcode exit db FCALL dw codetohere.p ; do code>here db FCALL dw heretoanon.p ; compile all to anon, not dictionary db EXIT begin.doc: ; db ' ( -- ) ; db ' marks a jump back address for until/again etc' ; db ' the jump address is left on the data stack ' ; db ' forth- : begin here ; immediate ' begin: dw semicolon.p db 'begin', IMMEDIATE | 5 begin.p: db FCALL dw here.p ; ad /current compilation adr db EXIT ; this could be written as source code ; need to change to ljump for long source code until.doc: ; db ' ( n -- ) ; db ' at run-time: jumps back to begin if n is true (non-zero)' ; db ' at compile-time: get begin address from data ' ; db ' stack and compile a conditional relative jump ' ; db ' back to begin. ' until: dw begin.p db 'until', IMMEDIATE | 5 until.p: ; as source ; : until [op'] jumpf c, here 1- - c, ; imm db LIT, JUMPF db LIT, 2 ; jb op 2 db FCALL dw itemcompile.p ; compile to current position (here) db FCALL dw here.p ; jb here db DECR ; jb here-1 /align to jump db MINUS ; jb-here-1 db FCALL dw ccomma.p ; compile to current position (here) db EXIT do.doc: ; db ' (run: limit start -- r: start limit ) ; db ' (comp: -- 'here' ) ; db ' At run-time: puts start and limit on return stack ' ; db ' at compile time: marks a jump back address for loop etc' ; db ' the jump address is left on the data stack ' %if 0 ; in source, can delete do: dw until.p db 'do', IMMEDIATE | 2 do.p: ; : do [op'] >r dup c, c, here ; imm db LIT, RON db FCALL dw ccomma.p db LIT, RON db FCALL dw ccomma.p ; mark code compile point to be used by loop to jump back db FCALL dw here.p ; ad /current compilation adr db EXIT %endif loop.doc: ; db ' (comp: 'here' -- ) (run: -- ) ; db ' at run-time: takes loop parameters off stack ' ; db ' increments the iterator, checks if it is = to limit ' ; db ' and jumps back to DO if not. If = then it removes loop ' ; db ' parameters from the stack and discards them. ' ; db ' at compile-time: get begin address from data ' ; db ' stack and compiles a rloop jump ' ; db ' back to begin (address on data stack). ' loop: dw until.p db 'loop', IMMEDIATE | 4 loop.p: ; as source ; : loop ; [op'] r> dup c, c, ; [op'] 1+ c, [op'] 2dup c, ; [op'] >r dup c, c, ; [op'] = c, ; [op'] jumpf c, ; here 1- - c, ; [op'] r> dup c, c, [op'] drop dup c, c, ; jump-back /left by DO on stack. ; could be better to write (loop) to call at run-time ; compile r> r> to get loop parameters off the stack db LIT, ROFF ; jb op db FCALL dw ccomma.p ; jb ; counter db LIT, ROFF ; jb op db FCALL dw ccomma.p ; jb ; increment the counter by 1 db LIT, INCR ; jb op db FCALL dw ccomma.p ; jb ; 2dup to save rstack values db LIT, TWODUP ; jb op db FCALL dw ccomma.p ; jb ; put them back on rstack db LIT, RON ; jb op db FCALL dw ccomma.p ; jb ; db LIT, RON ; jb op db FCALL dw ccomma.p ; jb ; check if counter==limit db LIT, EQUALS ; jb op db FCALL dw ccomma.p ; jb ; db LIT, JUMPF ; jb op=jumpt db FCALL dw ccomma.p ; compile opcode to current position (here) db FCALL dw here.p ; jb here db DECR ; jb here-1 /align to jump db MINUS ; jb-here-1 db FCALL dw ccomma.p ; compile to current position (here) ; now get rid of the loop parameters ; does: r> r> drop drop db LIT, ROFF ; op db FCALL dw ccomma.p ; db LIT, DROP ; op db FCALL dw ccomma.p ; db LIT, ROFF ; op db FCALL dw ccomma.p ; db LIT, DROP ; op db FCALL dw ccomma.p ; db EXIT %if 0 ; in source, can delete %endif ; this can be written as source but is useful for debugging ; bytecode words and so will be left. dotstack.doc: ; db ' ( -- ) ; db ' display the items on the data stack without ' ; db ' altering it. The top (or most recent) item ' ; db ' is printed rightmost ' dotstack: dw loop.p db '.s', 2 dotstack.p: ; below we need a copy of the stack depth ; because it gets decremented by the rloop ; need to sieve stack items onto rstack ; with >r, swap, r>, swap, >r etc db DEPTH, DUP ; n n db JUMPNZ, 4 ; n db DROP db EXIT ;*** put all items on return stack db DUP ; n n db RON ; n r: n db SWAP, ROFF ; n a n-x db SWAP, RON ; n n-x r: a db RON ; n r: a n-x db RLOOP, -5 ; n r: a n-x-1 db ROFF ; n 0 r: a b c ... db DROP ; n r: a b c ... ;*** print all stack items db RON ; r: a b c ... n db ROFF ; n r: a b c ... db ROFF ; n c r: a b db DUP ; n c c r: a b db FCALL ; this should be dw dot.p because stack is normally shown ; as signed numbers. See source version. dw udot.p ; n c r: a b db LIT, ' ', EMIT ; n c r: a b db SWAP, RON ; c r: a b n db RLOOP, -11 ; c r: a b n-1 db ROFF ; a b c ... 0 db DROP ; a b c ... db EXIT dotrstack.doc: ; db ' ( -- ) ; db ' display the top 2 items on the return stack ' dotrstack: dw dotstack.p db '.r2', 3 dotrstack.p: db LIT, ' ', EMIT db ROFF, ROFF ; n m db DUP ; n m m db FCALL dw udot.p ; n m db LIT, ' ', EMIT db RON ; n db DUP ; n n db FCALL dw udot.p ; n db RON db EXIT rcount.doc: ; db ' ( adr -- adr-n n ) ' ; db ' count a reverse counted string, ignoring control bit(s). ' ; db ' Given a pointer to the count byte of a ' ; db ' reverse counted string, return the address of the 1st byte ' ; db ' of the string and its length. This proceedure ' ; db ' may also handle the anding out of the immediate ' ; db ' control bit which is stored in the msb of the ' ; db ' count for execution tokens ' ; dw $-rcount.doc rcount: dw dotrstack.p db 'rcount', 6 rcount.p: ; adr db DUP, CFETCH ; a n / get the count db LIT, 0b00011111 ; a n mask db LOGAND ; a n&mask db DUP ; a n n db RON, MINUS ; adr-n db ROFF ; adr-n n db EXIT ; this doesnt seem to be used. can remove def.doc: ; db ' ( xt -- ) ' ; db ' Set the "defining" control bit in the count byte ' ; dw $-def.doc def: dw rcount.p db 'def', 3 def.p: ; adr db DECR ; adr-1 db DUP, CFETCH ; a n / get the count ; the def bit is the second bit in count byte db LIT, 0b01000000 ; a n mask db LOGOR ; a n.v.mask db SWAP ; m a db CSTORE ; db EXIT ; used by other bytecode so cant really rewrite as source dotxt.doc: ; db ' ( adr - ) ' ; db ' given a valid execution token on the stack ' ; db ' print the name of the procedure' ; db ' The source definition might be ; db ' : .xt -1 rcount type ; ' ; dw $-dotxt.doc dotxt: dw def.p db '.xt', 3 dotxt.p: ; xt db DECR ; adr-1 db FCALL dw rcount.p db FCALL dw type.p db EXIT xttoop.doc: ; db ' ( adr -- n ) ' ; db ' Given the address of an execution token ' ; db ' or procedure on the stack provides the numeric ' ; db ' opcode for that procedure or else 0 for ' ; db ' an address which does not correspond to a bytecode.' ; db ' This is used to compile text to bytecode ' ; db ' if not an opcode, then compile FCALL etc ' xttoop: dw dotxt.p db 'xt>op', 5 xttoop.p: ; adr db DUP ; adr adr db LITW ; dw op.table ; a a T db FETCHPLUS ; a a T+2 [T] db SWAP, RON ; a a [T] r: T+2 db EQUALS ; a flag r: T+2 db JUMPT, 19 ; a r: T+2 db DUP, ROFF ; a a T+2 ;**** check if end of table db DUP ; a a T+2 T+2 db FETCH ; a a T+2 [T+2] db LIT, -1 ; a a T+2 [T+2] -1 db EQUALS ; a a T+2 flag db JUMPF, .moreops-$ ; a a T+2 db DROP, DROP, DROP ; db LIT, 0 ; 0 / return false if not opcode db EXIT ; .moreops: db JUMP, -21 ; a a T+2 ;** opcode found, calculate offset db DROP, ROFF ; T+2 db DECR, DECR ; T db LITW dw op.table db MINUS ; T - optable db DIVTWO ; opcode db EXIT ; rewrite as source ( also rewrite decomp as source ) dotcode.doc: ; db ' ( opcode - ) ' ; db ' given a valid opcode on the stack, print ' ; db ' the textual version of the opcode. ' ; dw $-dotcode.doc dotcode: dw xttoop.p db '.code', 5 dotcode.p: ; op ;*** check for invalid code, nop always last db DUP ; op op db LIT, NOOP, INCR ; op op nop+1 db ULESSTHAN ; op flag db JUMPT, 12 ; op ;*** invalid code db FCALL dw udot.p db LIT, '?', EMIT db LIT, '?', EMIT db EXIT ;*** valid opcode db DUP, PLUS ; op*2 db LITW dw op.table ; op*2 op.table db PLUS ; op*2+op.table db FETCH ; [op*2+op.table] / get execution adr db DECR ; a-1 db FCALL dw rcount.p ; adr n ;*** does the same as rcount ;db DUP, CFETCH ; adr n / get the count ;db DUP ; adr n n ;db RON, MINUS ; adr-n ;db ROFF ; adr-n n db FCALL dw type.p db EXIT udot.doc: ; db ' ( n -- ) ' ; db ' display top stack element as unsigned ' ; db ' number in the current base. ' ; dw $-udot.doc udot: dw dotcode.p db 'u.', 2 udot.p: ; as source ; : u. ( n -- ) ; 0 >r ; begin ; base c@ ; \ n b r: count ; /mod r> 1+ >r ; ; rem quot ; dup ; until ; db LIT, 0, RON ; n r: 0 .divide: db LITW dw base.d ; n adr r: 0 db CFETCH ; n base db UDIVMOD ; rem quotient db ROFF, INCR, RON ; rem quotient r: 0+1 db DUP db JUMPNZ, .divide-$ ; rem rem rem ... 0 db DROP ; rem rem ... r: x ; as source ; drop r> 0 ; do ; digits ii + c@ emit ; loop drop ; ; .printc: db LITW ; use digit lookup table dw digits.d ; r r r ... adr r: x db PLUS ; r r ... adr+r r: x db CFETCH ; r r ... d r: x db EMIT ; rem ... print asci digit db RLOOP, .printc-$ ; rem ... r: x-1 db ROFF, DROP ; clear rstack db EXIT ; But this is also the way to print a double number, name clash ddot.doc: ; db ' ( n -- ) ' ; db ' display top stack element as unsigned ' ; db ' number in decimal ' ; dw $-ddot.doc ddot: dw udot.p db 'd.', 2 ddot.p: ; n db LIT, 0, RON ; n r: 0 db LIT, 10 ; n 10 r: 0 db DIVMOD ; rem quotient db ROFF, INCR, RON ; rem quotient r: 0+1 db DUP, JUMPNZ, -7 ; rem rem rem ... 0 r: x db DROP ; rem rem ... r: x db LIT, '0', PLUS, EMIT ; rem ... print remainder db RLOOP, -4 ; rem ... r: x-1 db ROFF, DROP ; clear rstack db EXIT dot.doc: ; db ' ( n -- ) ' ; db ' display top stack element as a signed number ' ; db ' in the current base (if u. does so) ' ; dw $-dot.doc dot: dw ddot.p db '.', 1 dot.p: ; n db DUP ; n n db LIT, 0 ; n n 0 db LESSTHAN ; n flag / n<0 ? db JUMPF, 6 ; n db NEGATE ; -n db LIT, '-', EMIT ; -n /print negative sign db FCALL dw udot.p db EXIT cdot.doc: ; db ' ( n -- ) ' ; db ' display top stack element as a signed 8 bit ' ; db ' number in the current base (if u. does so) ' ; db ' This is useful for displaying relative jumps ' ; db ' which are 1 byte signed numbers. ' ; db ' eg: 255 = -1, 254 = -2, 128 = -127 ; dw $-cdot.doc cdot: dw dot.p db 'c.', 2 cdot.p: ; n db DUP ; n n db LITW dw 128 ; n n 128 db LESSTHAN ; n flag / n < 128 db JUMPT, 6 ; n db LITW dw 256 db MINUS ; n-256 db FCALL dw dot.p db EXIT todigit.doc: ; db ' ( c -- n flag ) ' ; db ' converts the ascii character of a digit ' ; db ' on the stack to its corresponding integer ' ; db ' using the base (1digit', 6 todigit.p: ; c db DUP ; c c db LITW dw digits.d ; c c adr db LITW dw base.d ; c c adr adr db CFETCH ; c c a n db RON ; c c a r: n db CFETCHPLUS ; c c a+1 C r: n db SWAP, RON ; c c C r: n a+1 db EQUALS ; c flag r: n a+1 db JUMPT, 10 ; c r: n a+1 db DUP ; c c r: n a+1 db ROFF ; c c a+1 r: n db RLOOP, -8 ; c c a+1 r: n-1 ;*** not a valid digit db DROP, DROP ; c r: 0 db ROFF ; c 0 db EXIT ;*** valid asci digit, convert to number db DROP ; r: n-x a+1 db ROFF, DROP ; r: n-x db ROFF ; n-x db LITW dw base.d ; n-x adr db CFETCH ; n-x n db SWAP ; n n-x db MINUS ; x db LIT, -1 ; x -1 / -1 is true flag db EXIT digits.doc: ; db ' ( -- A ) ' digits: dw todigit.p db 'digits', 6 digits.p: db LITW dw digits.d db EXIT digits.d: db '0123456789ABCDEFGHijklmnopqrstuvwxyz' ; base is 16bits in all forths. so we can do: 10 base ! base.doc: ; db ' ( -- adr ) ' ; db ' puts on the stack the address of the current ' ; db ' numeric base ' ; db ' which is used for displaying and parsing ' ; db ' numbers. The base should be 1 < base < 37 ' ; db ' since these are the digits which can be ' ; db ' displayed using numerals and letters ' ; db ' eg: base c@ . ' ; db ' displays the current base ' ; dw $-base.doc base: dw digits.p db 'base', 4 base.p: db LITW dw base.d db EXIT base.d: db 10 %if 0 %endif tonumber.doc: ; db ' ( adr n -- adr/n flag ) ' ; db ' Given a pointer to string adr with length "n" ' ; db ' attempt to convert the string to ' ; db ' a number. If successful put number and true flag' ; db ' on the stack, if not put pointer to incorrect digit' ; dw $-tonumber.doc tonumber: dw base.p db '>number', 7 tonumber.p: ; a n db LIT, 0, RON ; a n r: 0 /false neg flag db RON ; a r: 0 n ;*** check for +/- at first char db DUP, CFETCH ; a c r: 0 n db LIT, '+' ; a c '+' ... db EQUALS ; a flag ... db JUMPF, 8 ; a ... db ROFF, DECR, RON ; a r: n-1 db INCR ; a+1 r: 0 n-1 db JUMP, 16 ; a+1 r: 0 n-1 db DUP, CFETCH ; a c r: 0 n db LIT, '-' ; a c '-' r: 0 n db EQUALS ; a flag r: 0 n db JUMPF, 9 ; a r: 0 n ;*** set a +/- flag on the rstack db ROFF, DECR ; a n-1 r: 0 db ROFF, DECR ; a n-1 -1 db RON, RON ; a r: -1 n-1 db INCR ; a+1 r: -1 n-1 ;*** exit if zero length string or just +/- db ROFF ; a n r: -1 db DUP ; a n n r: -1 db JUMPNZ, 5 ; a n r: -1 db ROFF, DROP ; a 0 db EXIT db RON ; a r: -1 n db LIT, 0 ; a 0 r: n /initial sum db SWAP ; 0 a r: n db CFETCHPLUS ; 0 a+1 d r: n ;*** check if digit db FCALL dw todigit.p ; 0 a+1 D flag r: n db JUMPF, 24 ; 0 a+1 D r: n ;*** db RON ; 0 a+1 r: n 0-9 db SWAP ; a+1 s r: n digit /s is sum db LITW dw base.d db CFETCH ; a+1 s base r: n digit db UMULT ; a+1 s*base r: n digit db ROFF ; a+1 s*base digit r: n db PLUS ; a+1 s r: -flag n db SWAP ; s a+1 r: -flag n db RLOOP, -16 ; s a+1 r: -flag n-1 /back to c@+ db ROFF, DROP ; s a+1 r: -flag db DROP ; s r: -flag db ROFF ; s -flag db JUMPF, 3 ; s / skip if + db NEGATE ; -s / negate if flag set db LIT, -1 ; s -1 /value and true flag db EXIT ;*** non digit ; sum a+1 d db DROP, SWAP ; a+1 sum r: 0 n db DROP ; a+1 r: 0 n db LIT, 0 ; a+1 0 db ROFF, DROP ; clear return stack db ROFF, DROP ; clear return stack db EXIT toword.doc: ; db ' ( -- adr n ) ' ; db ' put on the stack a pointer to the current ' ; db ' word and its length. ' toword: dw tonumber.p db '>word', 5 toword.p: ; handle zero case (no word found) db LITW dw toword.d ; adr db FETCH ; aw db DUP ; aw aw db LITW dw toin.d ; aw aw a db FETCH ; aw aw ap db SWAP ; aw ap aw db MINUS ; aw n db EXIT toword.d dw 0 ; pointer to start of current word wspace.doc: ; db ' ( c -- flag ) ' ; db ' return true if character c is whitepace (tab, space, 0 etc) ' wspace: dw toword.p db 'wspace', 6 wspace.p: ; stack diagram no good ; c ; space db DUP ; c c db LIT, ' ' ; c c space db EQUALS ; c flag db SWAP ; flag c ; carriage return db DUP ; c c db LIT, 10 ; c c space db EQUALS ; c flag db SWAP ; flag c ; newline db DUP ; flag c c db LIT, 13 ; flag c c cr db EQUALS ; flag c flag db SWAP ; f f c ; zero db DUP ; f f c c db LIT, 0 ; f f c c 0 db EQUALS ; f f c f db SWAP ; f f f c ; tab db DUP ; f f f c c db LIT, 9 ; f f f c c tab db EQUALS ; f f f c f db SWAP ; f f f f c ; combine flags db DROP ; f f f f db LOGOR ; f f f db LOGOR ; f f db LOGOR ; f db LOGOR ; f db EXIT wparse.doc: ; db ' ( -- adr n ) ' ; db ' return next word and length in the current input stream.' ; db ' the input stream is parsed for whitespace delimited words. ' ; db ' WPARSE skips initial whitespace. It is an important word ' ; db ' because it is the standard way to get the next word in ' ; db ' the current input stream, so things like CHAR and CREATE ' ; db ' rely on it. ; db ' For a more traditional forth "parse" see "parse.p" ' ; dw $-parse.doc wparse: dw wspace.p db 'wparse', 6 wparse.p: ; >in db FCALL dw toin.p ; adr n db DUP ; a n n ;*** no more text so nothing to parse db JUMPZ, .notext-$ ; a n ;*** get the name of the new word db RON ; adr r: n .nextspace: db CFETCHPLUS ; a+1 [a] r: n ; check for other whitespace, eg 0 tab, cr etc ; write a "whitespace" word db FCALL dw wspace.p ; a+1 flag r: n /true if whitespace ;db LIT, ' ' ; a+1 c space r: n ;db EQUALS ; a+1 flag ... db JUMPF, .nonspace-$ ; a+1 ... db RLOOP, .nextspace-$ ; a+1 r: n-1 ;*** no char found, so return 0 db DECR ; a r: 0 db ROFF ; a 0 db EXIT ; ;*** char found .nonspace: db DECR ; a r: n-m ;*** for debug ; db DUP, CFETCH, EMIT db DUP ; a a ... ;*** check rstack==0 and exit if so ;*** scan for next whitespace .nextchar: db CFETCHPLUS ; a a+1 [a] r: n-m ;*** check for whitespace character. db FCALL dw wspace.p ; a a+1 flag db JUMPT, .space-$ ; a a+1 ... db RLOOP, .nextchar-$ ; a a+1 r: n-m-1 db INCR ; a a+2 ... /balance decr ;*** .space: db DECR ; a a+p-1 r: 0 db ROFF, DROP ; a a+p-1 /clear rstack ;*** now calculate length of word db RON, DUP, ROFF ; a a a+p-1 db SWAP, MINUS ; a p-1 ; do 2dup, in+ at this point to advance the parse point ; in the input stream. db TWODUP ; a n a n db FCALL dw inplus.p ; a n db EXIT .notext: ; a 0 db EXIT ; the length returned may be +1 (?) ; this allows comments eg ; : ( 41 parse ; imm ; Can write this as source parse.doc: ; db ' ( char -- adr n ) ' ; db ' scan input stream for char and return length and address.' ; db ' The current input stream (IN) is scanned for the next char' ; db ' matching char. The parse position of the stream is advanced ' ; db ' after this call. If not found, then parse position and 0' ; db ' is returned.' ; dw $-parse.doc parse: dw wparse.p db 'parse', 5 parse.p: db RON ; r: char db FCALL dw toin.p ; adr n r: char db DUP ; a n n r: char ;* no more text so nothing to parse db JUMPZ, .notext-$ ; a n r: char ;* make the input stream length the counter db RON ; adr r: char n db DUP ; a a ... ;*** scan for next char .nextchar: db CFETCHPLUS ; a a+1 [a] r: char n ;*** check for scan character. db ROFF, ROFF ; a a+1 [a] n char db TWODUP ; a a+1 [a] n char n char db RON, RON ; a a+1 [a] n char r: char n db SWAP, DROP ; a a+1 [a] char r: char n db EQUALS ; a a+1 T/F r: char n ;db FCALL ;dw wspace.p ; a a+1 flag db JUMPT, .found-$ ; a a+1 r: char n db RLOOP, .nextchar-$ ; a a+1 r: char n .notfound: ; a a+n r: char 0 ; change the behaviour of parse so that it ; advances to the end of the stream if not found. ; db DROP ; a r: char 0 ; db ROFF, ROFF ; a 0 char ; db DROP ; a 0 ; db EXIT ;db INCR ; a a+2 ... /balance the next decr ;*** .found: ;db DECR ; a a+p-1 r: char 0 db ROFF, DROP ; a a+p-1 r: char /clear rstack db ROFF, DROP ; a a+p-1 /clear rstack ; calculate the length until the character db RON, DUP, ROFF ; a a a+p-1 db SWAP, MINUS ; a p-1 ; Advance the parse point in the input stream. db TWODUP ; a n a n db FCALL dw inplus.p ; a n ; decrement text length to ignore final delimiter character db DECR ; a n-1 db EXIT .notext: ; a 0 r: char db ROFF, DROP ; a 0 db EXIT ; this is almost identical to "source" inputcompile.doc: ; db ' ( -- ) ' ; db ' compiles the input stream starting from the current ' ; db ' input parse position until the end of the stream ' ; dw $-inputcompile.doc inputcompile: dw parse.p db 'in,', 3 inputcompile.p: .nextword: db FCALL dw wparse.p ; a+x n /address+length of next word ;*** if parse returns 0 then no more words (all space) db DUP ; a+x n n db JUMPZ, .endofstream-$ ; a+x n ;*** convert name to number/opcode/fpointer + flag db FCALL dw tick.p ; n/op/xt flag ;db FCALL ;dw dotstack.p ;*** if flag==0 abort, unknown word/number db DUP ; m flag flag db JUMPZ, .error-$ ; n/op/xt flag ;*** immediate words like if/fi begin will leave ; parameters on the data stack db FCALL dw itemcompile.p ; db JUMP, .nextword-$ .endofstream: ;*** no more words (>in returned zero) ;*** compile a final exit even if no semi-colon was ; given db DROP, DROP ; clear stack db LIT, EXIT db FCALL dw ccomma.p ; compile opcode EXIT db EXIT .error: ;db FCALL ;dw dotstack.p ; n/op/xt flag db LIT, 13, EMIT db LIT, 10, EMIT db DROP, DROP ; db FCALL dw toword.p ; ad n db LIT, 5, FG ; set word colour to cyan db FCALL dw type.p db LIT, 4, FG ; set word colour to red db LIT, ' ', EMIT db LIT, '?', EMIT db LIT, '?', EMIT db LIT, ' ', EMIT db LIT, '@', EMIT db LIT, 14, FG ; colour yellow db FCALL ; pointer to last word in dictionary dw last.p ; A db FETCH ; [A] db FCALL dw dotxt.p ; print out last word compiled db LIT, 7, FG ; set word colour to cyan db LIT, 13, EMIT db LIT, 10, EMIT ;*** compile an exit even when an error occurs ; db LIT, EXIT db FCALL dw ccomma.p ; compile opcode EXIT db EXIT ; now, should adr be a counted string? should we compile only one ; block (1K), or have another paramter to determine the length? ; this should be (adr length -- ). And source should be just the ; same word as inputcompile.p ; One problem: words outside of : defs are compiled to the anon ; buffer, and then need to be executed. Eg the immediate word ; source.doc: ; db ' ( adr n -- ) ' ; db ' compile forth source code from address adr ' ; db ' This is called "load" in many forths.' ; dw $-source.doc source: dw inputcompile.p db 'source', 6 source.p: ; need to save the current input stream and position ; eg in.d in.length toin.d and toword.d ; but where to save ? ;*** set "in" var to adr db FCALL dw resetin.p ; set in = adr = >in = >word db LITW dw anon.d db FCALL dw ishere.p ;*** rub out anon db LIT, EXIT db FCALL ; compile opcode exit dw ccomma.p db LITW dw anon.d db FCALL dw ishere.p ;*** compile input buffer db FCALL dw inputcompile.p .run: ; now run the compiled stuff ; but only run anon if it has something in it... db LITW dw anon.d db PCALL db FCALL dw ok.p db EXIT ok.doc: ; db ' ( -- ) ' ; db ' just prints ok ' ok: dw source.p db 'ok', 2 ok.p: ; db LIT, 13, EMIT ; db LIT, 10, EMIT db LIT, 2, FG ; set to green db LIT, ' ', EMIT db LIT, 'o', EMIT db LIT, 'k', EMIT db LIT, 7, FG ; set to white db LIT, 13, EMIT db LIT, 10, EMIT db EXIT %if 0 %endif ; with wordlists/namespaces, nfind will search "visible" namespaces in ; the search order given in the "namespace table". The search order ; will be a number before each namespace, or a list of pointers ; at the beginning of the table. Ans forth find is ( A -- xt ) ; where A is a counted string. nfind.doc: ; db ' ( adr n -- xt ) ' ; db ' return the execution address for the given word function. ' ; db ' Given a pointer to a string "adr" with length n ' ; db ' return the execution token (address) for the word' ; db ' or else zero if the word was not found. ' ; dw $-nfind.doc nfind: dw ok.p db 'nfind', 5 nfind.p: ; a n db FCALL ; pointer to last word in dictionary dw last.p ; a n A db FETCH ; a n last .again: db DECR ; point to count|control byte of name db FCALL dw rcount.p ; a n A N ;*** now compare the 2 string lengths n & N db SWAP ; a n N A db RON, RON ; a n r: A N db DUP, ROFF ; a n n N r: A db EQUALS ; a n flag r: A db JUMPF, .lengthsnotequal-$ ; a n r: A db ROFF ; a n A db SWAP ; a A n ;*** save values on rstack, clumsy db RON, RON, RON; r: n A a db ROFF, DUP ; a a r: n A db ROFF, DUP ; a a A A r: n db ROFF, DUP ; a a A A n n db RON, SWAP, RON ; a a A n r: n A ;*** compare two strings db FCALL ; are strings equal? dw ncompare.p ; a flag r: n A ; db JUMPF, .notequal-$ ; a r: n A ; if strings same clear stacks db DROP ; r: n A db ROFF, ROFF ; A n db PLUS, INCR ; A+n+1 ; A+n+1 is the execution address. found, so exit now db EXIT ; if false, balance stacks and jump down .notequal: ; a r: n A db ROFF, ROFF ; a A n db SWAP ; a n A db JUMP, 3 ; a n A /get next pointer .lengthsnotequal: db ROFF ; a n A db DECR, DECR ; a n A-2 /A-2 points to previous db FETCH ; a n [A-2] db DUP ; a n [A-2] [A-2] db JUMPNZ, .again-$ ; a n [A-2] db DROP, DROP, DROP ; clear stack db LIT, 0 ; zero means not found db EXIT immediate.doc: ; db ' ( -- ) ' ; db ' make the last word immediate. ' ; db ' Set the immediate control bit' immediate: dw nfind.p db 'imm', 3 immediate.p: db FCALL dw last.p ; addr db FETCH ; xt db DECR ; xt-1 db DUP ; xt-1 xt-1 db CFETCH ; xt-1 [xt-1] /get the count/control byte db LIT, IMMEDIATE ; xt-1 count|control 0b10000000 db LOGOR ; xt-1 nVimm / zero or non zero db SWAP ; m xt-1 db CSTORE ; trap! the count|control is only one byte db EXIT isimmediate.doc: ; db ' ( xt -- flag ) ' ; db ' returns 0 if word is not immediate. <>0 otherwise ' ; db ' given the execution address for a procedure ' ; db ' return a flag indicating if the procedure ' ; db ' is immediate or not. Immediate procedures are ' ; db ' executed at compile time, not compiled ' ; db ' so, essentially, they compile themselves. ' ; db ' this allows the compiler to be extended by ' ; db ' procedures. The immediate control bit is the ' ; db ' most significant bit of the count byte in the ' ; db ' name. Immediate words have both a compile-time and ' ; db ' a run-time behaviour, whereas non-immediate words ' ; db ' have only a run-time behaviour. isimmediate: dw immediate.p db 'imm?', 4 isimmediate.p: ; xt db DECR ; xt-1 db CFETCH ; [xt-1] /get the count byte db LIT, IMMEDIATE ; n 0b10000000 db LOGAND ; n & imm / zero or non zero db EXIT tick.doc: ; db ' ( A n -- n flag) ' ; db ' given a pointer "A" to a string of length n ' ; db ' attempt to convert the name to either ' ; db ' an opcode, procedure execution code, or number/integer ' ; db ' the flag indicates the type of token returned ' ; db ' a flag of zero means that the name is neither ' ; db ' number nor opcode nor xt' ; db ' flag=0 not number nor word ' ; db ' flag=1 if number, 2 if opcode, 3 if procedure ' ; dw $-tick.doc tick: dw isimmediate.p db 'tick', 4 tick.p: ; a n db TWODUP ; a n a n db FCALL dw nfind.p ; a n xt/0 db DUP ; a n xt xt db JUMPNZ, .opcode-$ ; a n xt ;*** not found, try to convert to number db DROP ; a n db FCALL dw tonumber.p ; adr/n flag db JUMPNZ, .number-$ ; adr/n ;*** not a number, push false flag and exit db LIT, 0 ; adr 0 db EXIT ;*** is a number .number: ; n db LIT, 1 ; n 1 /flag=1 means number db EXIT .opcode: ;*** check if opcode ; a n xt db SWAP, DROP ; a xt db SWAP, DROP ; xt db DUP ; xt xt db FCALL ; does this address correspond to an opcode dw xttoop.p ; xt op|0 db DUP ; xt op|0 op|0 db JUMPZ, .proceedure-$ ; xt op ;*** is an opcode db SWAP, DROP ; op /drop execution token address db LIT, 2 ; op 2 /flag=2 means opcode db EXIT .proceedure: ;*** must be procedure, ; xt 0=op db DROP ; xt db LIT, 3 ; xt 3 /flag=3 means procedure db EXIT ; This is only used by decomp.p args.doc: ; db ' ( op -- flag ) ' ; db ' given a valid opcode return flag=1 if the ' ; db ' the opcode requires a one byte ' ; db ' argument or return flag=2 if the opcode requires ' ; db ' a 2byte argument or flag=0 if no arguments required. ' ; dw $-args.doc args: dw tick.p db 'args', 4 args.p: ; lit, jump, jumpz, jumpnz, rloop db DUP ; op op db LIT, LIT ; op op op2 db EQUALS ; op flag db JUMPT, .one-$ ; op db DUP ; op op db LIT, JUMP ; op op op2 db EQUALS ; op flag db JUMPT, .one-$ ; op db DUP ; op op db LIT, JUMPZ ; op op op2 db EQUALS ; op flag db JUMPT, .one-$ ; op db DUP ; op op db LIT, JUMPNZ ; op op op2 db EQUALS ; op flag db JUMPT, .one-$ ; op db DUP ; op op db LIT, RLOOP ; op op op2 db EQUALS ; op flag db JUMPT, .one-$ ; op ; litw, fcall, ljump, db DUP ; op op db LIT, LITW ; op op op2 db EQUALS ; op flag db JUMPT, .two-$ ; op db DUP ; op op db LIT, FCALL ; op op op2 db EQUALS ; op flag db JUMPT, .two-$ ; op db DUP ; op op db LIT, LJUMP ; op op op2 db EQUALS ; op flag db JUMPT, .two-$ ; op .zero: db DROP db LIT, 0 ; 0 db EXIT .one: db DROP db LIT, 1 ; 1 db EXIT .two: db DROP db LIT, 2 ; 2 db EXIT debug.doc: ; db ' shows values for >code and here ' debug: dw args.p db 'debug', 5 debug.p: ; trying to see what is going on with >code and here db FCALL ; get dict compile point dw tocode.p ; code* db FETCH ; >code ; show the code point db LIT, 'c', EMIT db LIT, ':', EMIT db FCALL dw udot.p db LIT, ' ', EMIT db FCALL ; get here compile point dw here.p ; db LIT, 'h', EMIT db LIT, ':', EMIT db FCALL dw udot.p db EXIT sync.doc: ; db ' if >code is < here then make >code=here ' sync: dw debug.p db 'sync', 4 sync.p: db FCALL ; get dict compile point dw tocode.p ; code* db FETCH ; >code db FCALL ; get here compile point dw here.p ; >code here db ULESSTHAN ; flag=T/F db JUMPF, .end-$ ; ;db LIT, '*', EMIT ;db LIT, '<', EMIT ;db LIT, '*', EMIT ;db LIT, ' ', EMIT db FCALL ; get here compile point dw here.p ; >code here db FCALL ; get dict compile point dw tocode.p ; code* db STORE ; do: here >code ! ;db FCALL ; get dict compile point ;dw debug.p ; code* db EXIT .end: db EXIT ccomma.doc: ; db ' ( n -- ) ' ; db ' compile byte value n at next available byte ' ; b ' as given by here.p ' ; dw $-ccomp.doc ccomma: dw sync.p db 'c,', 2 ccomma.p: ;*** compile single byte db FCALL ; /get compile point dw here.p ; n adr db CSTOREPLUS ; a+1 db FCALL dw ishere.p ; /update compile point ; This crashes the system, not sure why... ;db FCALL ;dw sync.p ; /update compile point ; need to update >code if here is > than >code ; because custom defining words allocate data space in the ; dictionary. .end: db EXIT comma.doc: ; db ' ( n -- ) ' ; db ' compile 2 byte value at next available space ' ; db ' as given by the "here" variable ' ; db ' code: : , here !+ ishere ; ' ; dw $-comma.doc comma: dw ccomma.p db ',', 1 comma.p: db FCALL ; /get compile point dw here.p ; n adr db STOREPLUS ; a+2 db FCALL dw ishere.p ; /set compile point to new address (a+2) db EXIT ; trying to get dictionary compile point to advance db FCALL ; /get dict compile point dw tocode.p ; code* db FETCH ; >code db FCALL ; /get here compile point dw here.p ; >code here db INCR ; >code here+1 ; check if tocode < here+1 db ULESSTHAN ; flag=T/F db JUMPF, .end-$ ; ;db FCALL ;dw dotstack.p ;db KEY ;db EMIT ;db FCALL ;dw codetohere.p .end: scompile.doc: ; db ' ( adr n -- ) ' ; db ' compile the string at adr with length n to the ' ; b ' current compile position as given by here ' ; dw $-wordcompile.doc scompile: dw comma.p db 's,', 2 scompile.p: ; ad n ; if text length is 0 then do nothing. db DUP ; ad n n db JUMPNZ, .notzero-$ ; ad n db DROP, DROP ; db EXIT .notzero: ;*** n > 0 db RON ; ad r: n /n is loop counter .nextchar: db CFETCHPLUS ; ad+1 c r: n db FCALL dw ccomma.p ; ad+1 r: n db RLOOP, .nextchar-$ ; ad+1 r: n-1 db DROP ; r: 0 db ROFF, DROP ; /get rid of rloop counter db EXIT ; standard core forth word ; probably could write this as source sliteral.doc: ; db ' (comp: adr n -- ) (run: -- A n ) ' ; db ' compile the string at adr with length n to the ' ; db ' current definition. At run-time push the address ' ; db ' and length of the compiled string onto the stack ' ; dw $-sliteral.doc sliteral: dw scompile.p db 'sliteral', IMMEDIATE | 8 sliteral.p: ; ad n ; if text length is 0 then do nothing. db DUP ; ad n n db JUMPNZ, .notzero-$ ; ad n db DROP, DROP db EXIT .notzero: ; do other stuff here like compile ; code to push new A and n on stack at runtime ; ... compile jump db FCALL dw here.p ; ad n here ; adjust address by length of code about to be compiled db LIT, 8, PLUS ; ad n H+5 db FCALL dw literal.p ; ad n db DUP ; ad n n db FCALL dw literal.p ; ad n ; compile a jump over the string db LIT, JUMP ; ad n op=jump db FCALL dw ccomma.p ; ad n ; calculate and compile jump offset (jump over string) db DUP ; ad n n db LIT, 2, PLUS ; ad n n+2 db FCALL dw ccomma.p ; ad n ; copy the string to the current compile position db FCALL dw scompile.p db EXIT ; this doesnt always actually compile something (if it is ; an immediate word etc) so should be called something else ; like doword.p doitem.p itemcompile.doc: ; db ' ( n flag -- ) ' ; db ' compile item "n" at next availabe position ' ; b ' as given by "here" variable where flag indicates ' ; db ' the type of item. ' ; db ' flag=1 literal, 2 opcode, 3 procedure' ; dw $-compile.doc itemcompile: dw sliteral.p db 'item,', 5 itemcompile.p: ;*** 1=literal number eg: 1357, -10, 0 ; n flag db DUP ; n flag flag db LIT, 1, EQUALS ; n flag 0/-1 db JUMPZ, .notnumber-$ ; n flag ;*** check if state is immediate db FCALL dw state.p ; n flag adr db FETCH ; n flag state db JUMPT, .immediateNumber-$ ; n flag ;*** compile number db DROP ; n db LIT, LITW ; n op db FCALL ; /get compile point dw here.p ; n op adr db CSTOREPLUS ; n a+1 db STOREPLUS ; a+3 db FCALL dw ishere.p ; /update compile point db EXIT .immediateNumber: ; n flag ; do almost nothing because the number is already ; on the stack. db DROP ; n db EXIT .notnumber: ;*** check if is opcode ; n flag db DUP ; n flag flag db LIT, 2, EQUALS ; n flag 0/-1 db JUMPZ, .notopcode-$ ; n flag ;*** check if state is immediate db FCALL dw state.p ; op flag adr db FETCH ; op flag state db JUMPT, .immediateOp-$ ; n flag ;*** 2 is opcode ;*** compile the bytecode to given address db DROP ; op ; why not just use ccomma.p ?? db FCALL ; /get compile point dw here.p ; op adr db CSTOREPLUS ; adr+1 ' db FCALL ; /set compile point dw ishere.p ; db EXIT .immediateOp: ; op flag db DROP ; op db LITW ; dw obuff.d ; op adr db CSTOREPLUS ; adr+1 db LIT, EXIT ; a+1 op=exit db SWAP ; op a+1 db CSTORE ; ; now actually execute the opcode db LITW ; dw obuff.d ; adr db PCALL db EXIT .notopcode: ;*** check if procedure ; n flag db DUP ; n flag flag db LIT, 3, EQUALS ; n flag 0/-1 db JUMPF, .error-$ ; n flag ;*** 3 procedure ; xt flag db DROP ; xt ;*** check if word is immediate db DUP ; xt xt db FCALL dw isimmediate.p ; xt flag db JUMPT, .immediate-$ ; xt ; bug! bug! This only applies to procedures, not ; opcodes, so even if state is immediate, opcodes and ; numbers will not be executed immediately. I think this ; is a problem. ;*** check if state is immediate ; xt db FCALL dw state.p ; xt adr db FETCH ; xt state db JUMPT, .immediate-$ ; xt ;*** neither word nor state is immediate, so compile db LIT, FCALL ; xt op db FCALL ; /get compile point dw here.p ; xt op adr db CSTOREPLUS ; xt adr+1 db STOREPLUS ; adr+3 db FCALL ; /set compile point dw ishere.p ; db EXIT ;*** immediate proc, execute, dont compile .immediate: db PCALL db EXIT .error: ; n flag db DROP, DROP db EXIT ; rewrite as source headdot.doc: ; db ' ( xt -- ) ' ; db ' show the dictionary header for a word function. ' ; db ' The word header is shown in a form suitable for ' ; db ' debugging. ' ; dw $-headdot.doc headdot: dw itemcompile.p db 'head.', 5 headdot.p: ; xt db DUP ; xt xt db DECR ; xt xt-1 /points to count|control byte db FCALL dw rcount.p ; xt adr n /start of name db DROP ; xt adr db DECR, DECR ; xt adr-2 ;db FETCH ; XT / get word pointer ;*** print head memory address db LIT, 13, EMIT db LIT, 10, EMIT db DUP ; xt a a db FCALL dw udot.p ; xt a db LIT, ':', EMIT db LIT, ' ', EMIT ;*** print the link address to next word in dictionary db LIT, '[', EMIT db FETCH ; xt [a] db DUP ; xt [a] [a] db FCALL dw udot.p ; xt [a] db LIT, ']', EMIT db LIT, ' ', EMIT db LIT, '-', EMIT db LIT, '>', EMIT db LIT, ' ', EMIT ;*** print the name of the linked word db DECR ; xt A-1 /point to count|control byte db FCALL dw rcount.p ; xt A-n n db FCALL dw type.p ; xt db LIT, 13, EMIT ; db LIT, 10, EMIT ; db DECR ; xt-1 /point to count|control byte db FCALL dw rcount.p ; a-n n db RON, DUP ; a-n a-n R: n db FCALL dw udot.p ; a-n R: n db LIT, ':', EMIT db LIT, ' ', EMIT db ROFF ; a-n n db DUP, RON ; a-n n R: n ;*** print word name in quotes db LIT, '"', EMIT db FCALL dw type.p ; R: n db LIT, '"', EMIT db ROFF ; n db LIT, ' ', EMIT ;*** print word length|control in quotes ;!! need to handle immediate words which have msb set db FCALL dw udot.p ; db LIT, 13, EMIT ; db LIT, 10, EMIT ; db EXIT ; rewrite as source worddump.doc: ; db ' ( xt -- ) ' ; db ' shows how a word is compiled in the dictionary ' ; db ' The dictionary header and compiled code is displayed ' ; db ' for the word corresponding to the execution address. ' ; dw $-worddump.doc worddump: dw headdot.p db '..word', 6 worddump.p: db DUP ; xt xt db FCALL dw headdot.p ; xt db LIT, 50 ; xt n /decompile up to n bytes db FCALL dw decomp.p db EXIT ; : word.. dup head. 20 decomp ; decomp.doc: ; db ' ( adr n -- a2 ) ' ; db '' ; db ' decompiles n bytes starting at address n ' ; db ' returns the next address after the decompiled ' ; db ' bytes. Need to handle jumps too. This cannot decompile' ; db ' machine code, only bytecodes ' ; dw $-decomp.doc decomp: dw worddump.p db 'un,', 3 decomp.p: ; adr n db RON ; adr r: n ; as source ; decomp ( A n - A' ) ; >r 0 do ; \ A ; cr dup u. ." : " emit ; c@+ ; loop .again: db LIT, 13, EMIT db LIT, 10, EMIT db DUP ; a a db FCALL dw udot.p ; a db LIT, ':', EMIT db LIT, ' ', EMIT db CFETCHPLUS ; a+1 c r: n db DUP ; a+1 c c db JUMPZ, .invalid-$ ; a+1 c db DUP, LIT, NOOP, INCR ; a+1 c c op+1 r: n db ULESSTHAN ; a+1 c flag r: n db JUMPT, .valid-$ ; a+1 c r: n ;*** invalid opcode .invalid: ; a+x c db FCALL dw udot.p db LIT, '?', EMIT ;*** clear rstack db ROFF, DROP db EXIT .valid: ;*** valid opcode db DUP ; a+1 c c r: n db FCALL dw dotcode.p ; a+1 c r: n db LIT, ' ', EMIT ;*** is fcall db DUP ; a+1 c c r: n db LIT, FCALL ; a+1 c c op r: n db EQUALS ; a+1 c flag ... db JUMPF, 21 ; a+1 c ... ;*** fcall, get xt db DROP ; a+1 ... db FETCHPLUS ; a+3 xt ... db LIT, '<', EMIT db FCALL dw dotxt.p ; a+3 r: n db LIT, '>', EMIT db LIT, ' ', EMIT db RLOOP, .again-$ ; a+3 r: n-1 db ROFF, DROP ; clear rstack db EXIT ;*** check if 1 or 2 byte argument or non db DUP ; a+1 c c r: n db FCALL dw args.p ; a+1 c args r: n db DUP ; a+1 c args args r: n db JUMPZ, .zerobytes-$ ; a+1 c args ... db LIT, 1, EQUALS ; a+1 c flag db JUMPT, .onebyte-$ ; a+1 c ;*** opcode takes 2 byte argument .twobytes: db DROP ; a+1 ... db FETCHPLUS ; a+3 xt ... db LIT, '<', EMIT db FCALL dw dot.p ; a+3 r: n db LIT, '>', EMIT db LIT, ' ', EMIT db RLOOP, .again-$ ; a+3 r: n-1 db ROFF, DROP ; clear rstack db EXIT ;*** opcode takes 1 byte argument .onebyte: db DROP ; a+1 ... db CFETCHPLUS ; a+2 n ... db LIT, '<', EMIT ;*** cdot prints 8 bit number as signed db FCALL dw cdot.p ; a+2 r: n db LIT, '>', EMIT db LIT, ' ', EMIT db RLOOP, .again-$ ; a+2 r: n-1 db ROFF, DROP ; clear rstack db EXIT ;*** opcode takes no argument .zerobytes: ; a+1 c args ... db DROP, DROP db RLOOP, .again-$ ; a+1 r: n-1 db ROFF, DROP ; clear rstack db EXIT ; The dictionary pointer is called "dp" in pforth and gforth tocode.doc: ; db ' ( -- adr ) ' ; db ' puts on the stack a pointer to the next available byte' ; db ' in the dictionary. ' ; dw $-tocode.doc tocode: dw decomp.p db '>code', 5 tocode.p: db LITW dw tocode.d ; db FETCH / maybe not db EXIT tocode.d: dw dictionary codetohere.doc: ; db ' ( -- ) ' ; db ' sets the dict compile point to the here var' ; dw $-codetohere.doc codetohere: dw tocode.p db 'code>here', 9 codetohere.p: db FCALL dw here.p ; a db LITW dw tocode.d ; a A db STORE ; db EXIT ; this is an important word because it is called by ; create, and therefore all defining words. In this implementation ; of forth it writes an exit to end of anon (here) and ; then executes the anon buffer. This is because this forth ; is a "compiling" forth, rather than an "interpreted" forth, ; so the default behavior is to compile even interactive commands heretocode.doc: ; db ' ( -- ) ' ; db ' sets the here var to the dict compile point' ; dw $-codetohere.doc heretocode: dw codetohere.p db 'here>code', 9 heretocode.p: db LIT, EXIT ; op=exit db FCALL dw ccomma.p ; compile exit op to end of anon (at "here") db FCALL ; execute everything in the anon buffer dw anon.d ; need to "empty" the anon buffer after executing ; to avoid multiple unwanted calls db FCALL ; set here to start dw heretoanon.p db LIT, EXIT ; op=exit db FCALL dw ccomma.p ; compile EXIT op to start of anon (at "here") db LITW dw tocode.d ; >code* db FETCH ; [>code] db LITW dw here.d ; [>code] a db STORE ; db EXIT ; Perhaps we should compile everything first to the "anon" buffer!! ; even new dictionary entries, and then copy them across to ; the dict. This seems to simplify the semantics of all this. ; No, the anon buffer will just be a pointer, not a buffer heretoanon.doc: ; db ' ( -- ) ' ; db ' sets the compile point to the start of the anon buffer' ; dw $-heretoanon.doc heretoanon: dw heretocode.p db 'here>anon', 9 heretoanon.p: db LITW dw anon.d ; anon* db LITW dw here.d ; anon* here* db STORE ; db EXIT here.doc: ; db ' ( -- adr ) ' ; db ' puts on the stack the current compile position' ; db ' in the code data space ' ; dw $-here.doc here: dw heretoanon.p db 'here', 4 here.p: db LITW dw here.d db FETCH db EXIT here.d: dw 0 ; pointer to next byte ishere.doc: ;db ' ( adr -- ) ' ;db ' set position of next available byte' ;db ' for compilation ("here" variable) to address adr' ;dw $-ishere.doc ishere: dw here.p db 'here!', 5 ishere.p: ; adr db DUP ; A A db LITW dw here.d ; A A b db STORE ; A ; this seems the right place to update the dictionary ; compile point, if necessary, but it is not working. db FCALL ; dw tocode.p ; A C* db FETCH ; A C ; debug ;db TWODUP ;db FCALL ;dw udot.p ;db LIT, ' ', EMIT ; ;db FCALL ;dw udot.p ;db LIT, ' ', EMIT ; db ULESSTHAN ; t/f db JUMPT, .end-$ ;db FCALL ;dw codetohere.p .end: db EXIT ; according to standard forth docs, this should not be modified by ; forth words except [ ] etc. ; [ and ] are be defined in source as ; : [ 1 state ! ; immediate ; : ] 0 state ! ; immediate state.doc: ; db ' ( -- adr ) ' ; db ' pushes a pointer to current state (immediate or compile)' ; db ' modified by [ and ] only (not by colon) ' ; db ' state 0=normal/compile state 1=immediate ' ; dw $-state.doc state: dw ishere.p db 'state', 5 state.p: db LITW dw state.d db EXIT state.d: dw 0 first.doc: ; db ' ( -- adr ) ' ; db ' address of first buffer (for loading source from disk)' ; dw $-first.doc first: dw state.p db 'first', 5 first.p: db LITW dw first.d db FETCH db EXIT ; near the end of this segment, just for testing. ; in reality should be just after the dictionary or stack ; remember distinction between disk map and ram memory map first.d: dw 50*1024 blockone.doc: ; db ' ( -- adr ) ' ; db ' sector number of first source block (1K) on disk' ; db ' each sector is 512 bytes in length. ' ; dw $-blockone.doc blockone: dw first.p db 'block1', 6 blockone.p: db LITW ; the 1+ is a hack because this is 1 short for some ; reason dw 1+(diskcode-$$)/512 db EXIT ; "a" is top of stack. ie rightmost is last-on first-off copy.doc: ; db ' ( A n a -- ) ' ; db ' copy n bytes from address A to address a ' ; db ' this cannot deal with overlapping memory areas. ' ; dw $-copy.doc copy: dw blockone.p db 'copy', 4 copy.p: ; A n a db SWAP ; A a n db RON ; A a r: n /n loop counter db SWAP ; a A .again: db CFETCHPLUS ; a A+1 [A] ; db DUP, EMIT ; debug db SWAP ; a [A] A+1 db RON ; a [A] r: n A+1 db SWAP ; [A] a r: n A+1 db CSTOREPLUS ; a+1 r: n A+1 db ROFF ; a+1 A+1 r: n db RLOOP, .again-$ ; a+1 A+1 r: n-1 db ROFF ; a+n A+n 0 db DROP, DROP, DROP ; db EXIT ; Ans forth compare is ( cA n cB m -- 0/-1/1 ) ; zero means strings are equal -1 1st is "smaller" 1 opposite ; I should rename this ncompare to get out of the way of ; the standard forth word. Or this should be called nstr= ; because Ans compare returns more than a flag. ncompare.doc: ; db ' ( a A n -- flag) ' ; db ' given 2 pointers to strings a and A ' ; db ' compare the 2 strings for n bytes ' ; db ' and put -1=true on stack as flag if the strings are ' ; db ' the same or false=0 on stack if the strings ' ; db ' are different. ' ; dw $-ncompare.doc ncompare: dw copy.p db 'ncompare', 8 ncompare.p: ; a A n db RON ; a A r: n /n loop counter db CFETCHPLUS ; a A+1 [A] ; db DUP, EMIT ; debug db SWAP ; a [A] A+1 db RON, RON ; a r: n A+1 [A] db CFETCHPLUS ; a+1 [a] r: n A+1 [A] ; db DUP, EMIT ; debug db ROFF ; a+1 [a] [A] r: n A+1 db EQUALS ; a+1 flag r: n A+1 db JUMPT, 10 ; a+1 r: n A+1 db ROFF, ROFF ; a+1 A+1 n db DROP, DROP, DROP ; clear stacks db LIT, 0 ; flag=0 (false) db EXIT db ROFF ; a+1 A+1 r: n db RLOOP, -18 ; a+1 A+1 r: n-1 db ROFF ; a+n A+n 0 db DROP, DROP, DROP ; clear stacks db LIT, -1 db EXIT type.doc: ; db ' ( adr n -- ) ' ; db ' Prints out n number of characters starting ' ; db ' at address adr. ' ; dw $-type.doc type: dw ncompare.p db 'type', 4 type.p: ; adr n ;*** if count zero, do nothing db DUP ; adr n n db JUMPNZ, .sometext-$ ; adr n db DROP, DROP ; clear data stack db EXIT .sometext: db RON ; adr r: n .nextchar: db CFETCHPLUS ; adr+1 c r: n db EMIT ; adr+1 r: n db RLOOP, .nextchar-$ ; adr+1 r: n-1 db ROFF, DROP, DROP ; clear stacks db EXIT %if 0 ; in source, so can delete this bytecode. accept.doc: ; db ' ( buffer -- ) ; db ' receive a line of input from the terminal ' ; db ' and store it as a counted string in the buffer. ' ; db ' should have a character limit. backspaces are mainly ; db ' handled. ' ; dw $-accept.doc accept: dw type.p db 'accept.byte', 11 accept.p: ;*** to elimate backspace problems, need to ; emit character after finding out what it is ; not before ; a db DUP, RON ; a r: a db INCR ; a+1 r: a .nextkey: db KEY, DUP ; a+1 c c r: a db DUP, EMIT ; a+1 c c r: a ;*** enter terminates input db LIT, 13, EQUALS ; a+1 c flag r: a /enter press db JUMPT, .exit-$ ; a+1 c r: a ;*** handle backspace db DUP ; a+1 c c r: a db LIT, 8, EQUALS ; a+1 c flag r: a /backspace db JUMPF, .notback-$ ; a+1 c r: a db DROP ; a+1 r: a ;*** test for at 1st char db DUP ; a+1 a+1 r: a db ROFF, DUP, RON ; a+1 a+1 a r: a db MINUS ; a+1 n r: a db LIT, 1 ; a+1 n 1 r: a db EQUALS ; a+1 flag r: a db JUMPT, .nextkey-$ ;*** not 1st char so go back 1 space db LIT, ' ', EMIT ; a+n r: a db LIT, 8, EMIT ; go back db DECR ; a+n-1 r: a db JUMP, .nextkey-$ ; a+n-1 r: a /get next char ; put the character limit test here. .notback: db SWAP ; c a+1 r: a db CSTOREPLUS ; a+2 r: a db JUMP, .nextkey-$ ; a+2 r: a .exit: db LIT, 10, EMIT ; print newline if enter pressed db LIT, 13, EMIT ; db DROP ; a+n r: a db ROFF ; a+n a db DUP, RON ; a+n a r: a db MINUS ; n r: a db DECR ; n-1 r: a db ROFF ; n-1 a db CSTORE db EXIT %endif in.doc: ; db ' ( -- adr ) ; db 'Puts on the stack the address of the ' ; db 'current input source/ buffer ' ; dw $-in.doc in: dw type.p db 'in', 2 in.p: db LITW dw in.d db EXIT in.d: dw 0 ; need to initialize in.length: dw 0 ; need to initialize term.doc: ; db ' ( -- adr ) ; db 'Puts on the stack the address of the ' ; db 'user input buffer (terminal buffer). This' ; db 'is a common source for interpreting and ' ; db ' compiling ' ; dw $-term.doc term: dw in.p db 'term', 4 term.p: db LITW dw term.d db EXIT term.d: times 128 db 0 ; counted buffer for user input dotin.doc: ; db ' ( -- ) ; db 'display the contents of the current input stream ' ; db 'or buffer. ' ; dw $-dotin.doc dotin: dw term.p db '.in', 3 dotin.p: ; change this because the input stream is not always a ; counted string db LITW dw in.d ; adr db COUNT ; a+1 n db DUP ; a+1 n n db FCALL dw udot.p ; a+1 n db LIT, ':', EMIT ; a+1 n db FCALL dw type.p db EXIT ; : in.. in count dup u. sp type ; toin.doc: ; db ' ( -- adr n ) ' ; db ' put on stack parse position in input stream' ; db ' and number of characters remaining in stream. ' ; db ' This is used with parse etc' ; dw $-toin.doc ; was a strange bug with this link toin: dw dotin.p db '>in', 3 toin.p: ;** need to remember that in.length, toin.d and in.d are ; pointers and need to be fetched before use... *p ; db LITW dw toin.d ; adr db FETCH ; >in db DUP ; >in >in db LITW dw in.d ; >in >in in.d db FETCH ; >in >in in db MINUS ; >in offset db LITW dw in.length ; >in offset adr db FETCH ; >in offset [in.length] db SWAP ; >in length offset db MINUS ; >in remainder ;db FCALL ;dw dotstack.p db EXIT toin.d: dw 0 ; maybe call this setin or in! instore or in+ ; why not just get adr and n from >word? inplus.doc: ; db ' ( adr n -- ) ' ; db ' update word and parse position in input' ; db ' where the start of the word is given by pointer' ; db ' adr and the length of the word is n. The parse ' ; db ' position will be adr+n after this call ' ; db ' eg: pad resetin pad accept >in parse 2dup type ' ; db ' atin >in .s etc' ; dw $-inplus.doc inplus: dw toin.p db 'in+', 3 inplus.p: ; probably should check here that the new ; parse position is not beyond the end ; of the input stream (length) ; adr n db SWAP, DUP ; n adr adr db LITW dw toword.d ; n adr adr a2 db STORE ; n adr db PLUS ; n+adr db LITW dw toin.d ; n+adr ap db STORE ; db EXIT ; we dont actually use the toword.p proceedure. resetin.doc: ; db ' ( adr n -- ) ' ; db ' set word and parse position to 0 in input' ; db ' and set the input buffer to point to address ' ; db ' adr and the stream length to n. ' ; db ' set vars in.d in.length toin.d toword.d ' ; dw $-resetin.doc resetin: dw inplus.p db 'in0', 3 resetin.p: ; adr n db LITW dw in.length ; adr n in.length db STORE ; adr db DUP ; adr adr db LITW dw in.d ; adr adr in.d db STORE ; adr db DUP ; adr adr db LITW dw toin.d ; adr adr toin.d db STORE ; adr db LITW dw toword.d ; adr word.d db STORE ; db EXIT anon.doc: ; db ' ( -- adr ) ; db 'Puts on the stack the address of the ' ; db 'buffer to hold anonymous definitions. This ' ; db 'contains compiled byte code for user input ' ; dw $-anon.doc anon: dw resetin.p db 'anon', 4 anon.p: db LITW dw anon.d db EXIT anon.d: times 128 db 0 ; compiled byte code ; Another idea instead of obuff is just to use memory after the ; last word in the dictionary. Eg: ; : obuff here 128 + ; obuff.doc: ; db ' ( -- adr ) ; db ' A buffer used to execute opcodes which have been ' ; db ' called in immediate state. ; dw $-obuff.doc obuff: dw anon.p db 'obuff', 5 obuff.p: db LITW dw obuff.d db EXIT ; this will contain one opcode and EXIT, so only 2 bytes obuff.d: times 4 db 0 ; buff.doc: ; db ' ( -- adr ) ; db ' a testing buffer' ; dw $-buff.doc buff: dw obuff.p db 'buff', 4 buff.p: db LITW dw buff.d db EXIT buff.d: times 64 db 0 ; compiled byte code pad.doc: ; db ' ( -- adr ) ; db 'Puts on the stack the address of the general purpose ' ; db 'text buffer ' ; dw $-pad.doc pad: dw buff.p db 'pad', 3 pad.p: db LITW dw pad.d db EXIT pad.d: times 128 db 0 drive.doc: ; db ' ( -- adr ) ; db ' a variable to hold virtual drive number ' dw pad.p db 'drive', 5 drive.p: db LITW dw drive.d ; ad db EXIT drive.d: db -1 sides.doc: ; db ' ( -- adr ) ; db ' how many sides or platters a disk has. ' ; db ' This information may be needed for disk reads. ' dw drive.p db 'sides', 5 sides.p: db LITW dw sides.d db EXIT sides.d: dw -1 sectorspertrack.doc: ; db ' ( -- adr ) ; db ' How many sectors each track has. eg 18 for floppy ' ; db ' This information may be needed for disk reads. ' dw sides.p db 'sectors', 7 sectorspertrack.p: db LITW dw sectorspertrack.d db EXIT sectorspertrack.d: dw -1 lib.doc: ; db ' ( -- adr ) ; db ' some source code to load' ; dw $-lib.doc lib: dw sectorspertrack.p db 'lib', 3 lib.p: db LITW dw lib.d db EXIT lib.d: db lib.end-$-1 ; number of characters (used by source and type) ; block1 is the sector (512 byte block) of the first ; source code block (forth block=1K bytes) on disk ; actually parse and compile this source code ; use clock to time compile time db ' 52 emit 116 emit 104 emit 33 emit 13 emit 10 emit' ; message "4th!" db ' clock ' ; load the 0 block, which loads all the others db ' block1 2 first read drop first 1024 source ' db ' clock ' ;db ' timer cr .s ' lib.end: ; Here we can make a "fake" wordlist "forth" or core etc. ; It is just a buffer with a datafield containing a ; pointer to the last word in the dictionary. Once ; the compiler is booted up, it can make real vocabs with ; the vocab word and add new words to them. ; fake vocabulary. It may not even need a "head" namefield etc. ; when "create" runs it should update this link instead of ; last.d So, initially, before create has run, the last ; word in the dictionary (bytecode) is "last.p". To get a pointer ; we must do current @ @ or else FCALL, last.p ; forth.d: dw last.p current.doc: ; db ' ( -- adr ) ; db 'Puts on the stack a pointer to current wordlist ' ; db 'for new definitions. The word "last" will just current: dw lib.p db 'current', 7 current.p: db LITW dw current.d ; ad db EXIT ; actually current.d needs to point to a wordlist datafield ; not to the actually last word in that list.. This is ; so "order" can display what is the current wordlist ; So last can do "current @ @" to actually get a pointer ?? ; to the last word in the list, but we cant do "A last !" ; anymore?. This is confusing, but pointers to pointers always ; are. current.d: dw forth.d ; This implementation may change with name spaces. Last ; may point to the last word of the "current" definition namespace ; (wordlist/vocabulary) ; ; With wordlists... make last.d a pointer to a pointer (pointing ; to "current" variable. Make "last" or "latest" word resolve ; double pointer into xt of last word in current definition ; wordlist. This allows us to add new words to new wordlists. ; Put "current" in bytecode? What happens if wordlist is ; empty? Need to create a new word with a zero back link. ; Maybe create needs to deal with that. But no, this doesnt ; quite work because bytecode assumes that last is a var to ; use with @ and !. A pointer to a pointer cant be used that ; way. last.doc: ; db ' ( -- adr ) ; db 'Puts on the stack a pointer to (xt) address of the last word ' ; db 'in the dictionary. This changes when new words are ' ; db 'added via colon : definitions or other defining words ' last: dw current.p ; normally called "latest" I think db 'last', 4 last.p: db LITW dw last.d ; ad db EXIT last.d: dw last.p code: db JUMP, .system-$ .system: ; lib.p just loads the 1st block (block 0) which loads the ; other disk source code blocks and then compiles and runs ; 'shell' which is the repl interpreter (normally called 'quit' ; in forth) db FCALL dw lib.p db COUNT ; source takes address + length db FCALL dw source.p ;db FCALL ;dw shell.p db 0 start: mov ax, cs ; cs is already correct (?!) mov ds, ax ; data segment ;*** save the (virtual) drive we have loaded ; code from. Handy for disk writes later ; have to set data segment DS first ; get the disk geometry parameters and save for use by ; read.x ; code from mike gonta. This fixed read problems where there ; are more than 18 sectors on a track etc. mov [drive.d], byte dl ; mov ah, 8 int 13h ; jc .diskerror and cx, 3Fh mov [sectorspertrack.d], cx movzx dx, dh add dx, 1 mov [sides.d], dx ; point es:di directly after the code and data segment ; i.e. after the 8 sectors (8 * 512 bytes) ; which contain code and data. We will use es:di ; as the return stack pointer. When ; a value is pushed on the return stack, the value ; is written to [es:di] and di is incremented by 2 ; add ax, 256 ; 256 * 16 = 4096, 4K (8 sectors) ; put a gap of 4K between code and stacks for ; dictionary entries etc ;*** 8K code + 8K gap then rstack. But are the data and ; return stacks growing towards each other??? ;add ax, 512 ; 512 * 16 = 8K add ax, 1024 ; 1024 * 16 = 16K mov es, ax ; using es:di as return stack pointer mov di, 0 ; the calculations are as follows ; we have loaded 16 sectors = 16 * 512 bytes = 9162 bytes == 8K ; we want a data stack of size 4K ; (which is big) = 4094 bytes ; also we want a return stack of size 4K/8K ; for hefty recursive functions, although these ; huge sizes are not necessary. ; x86 hardware stack grows up or down? ... ; divide by 16 because that is how segment ; addressing works ; That is: if we multiply the number in ss or es ; or ds by 16 ; we get a absolute memory address ;*** ax is pointing to start of the rstack so ;*** add 4K more for data stack add ax, 256 ; 256*16=4K mov ss, ax ; a 4K stack here mov sp, 4096 ; set up the stack pointer push code call exec.x stayhere: jmp stayhere ;*** new words can be compiled here ; dictionary: dw 0 ; Pad remainder of n( = n/2 K) sectors with 0s ; The number below (6,7,8 etc) only has to be as big ; as the dictionary. times (6*1024)-($-$$) db 0 ; MEMORY MAP (may 2018) ; To avoid confusion, remember the clear distinction between ; the disk map (code and data on disk) and the ram memory map. ; ; need to clarify this memory map. ; This may change as code grows, but the idea is to keep code small ; The addresses below are segmented, so multiply the first part by ; 16 to get the real address. ; ; address contents ; ------- -------- ; 1000:0000 8K of code and data, including the dictionary ; and any new words defined by colon : ; ??:0000 8K return stack pointed to by es:di ; ??:0000 4K data stack pointed to by ss:sp ; ; this is silly, can erase memory without writing to disk ; in fact, is there any need to erase stack memory? ; times 4096 db 0 ;*** some text/forth code at sector ? which we can load ;*** with source.p or with load opcode diskcode: ; can load this with "block1 2 first read first 1024 source" block1: ; see os.sed for a proprocessing sed script. ; This script allows us to write multiline ; forth source code without the "db ' " guff. %if 0 ; code{ ; switch to video mode 16 (x86 bios colours, no cursor), not portable ; or text mode 3 3 vid ; standard ' tick (?). There is another word TICK which works ; a bit differently since it returns a flag as well indicating ; if the word is a number, opcode or fcall. : ' wparse nfind ; imm ; if call, is not immediate then this gets simpler ; does it need to be immediate? ; ans forth 'postpone' word. Compiles a call to a word, even if ; it is immediate. This is used in words like [char] but is tricky ; to think about somethimes. : post wparse nfind ' call, call, ; imm ; a ' to use in colon defs : ['] wparse nfind post literal ; imm ; makes all words execute immediately until ] ' ; This word sets the state variable to true (immediate) ' ; so that all words parsed will execute immediately ' ; without being compiled. ' : [ 1 state ! ; imm ; This word sets the state variable to false (normal) ; so that all words parsed will be compiled unless they ; have their immediate control bit set. : ] 0 state ! ; imm ; Put the value of the following character on the stack : char wparse drop c@ ; imm ; standard [char] : [char] post char post literal ; imm ; An alias for [char] that is shorter ; : /c/ post char post literal ; imm : /c/ post [char] ; imm ; comments like ( -- ) : ( [char] ) parse drop drop ; imm ; ans forth word, add n to [A] and store at A ; eforth definition : +! ( n A -- ) swap over @ + swap ! ; ;: +! ( n A -- ) 2dup @ + swap ! drop ; ; a modulus operator : mod /mod drop ; ; integer division : / /mod swap drop ; ; type a space : space ( -- ) 32 emit ; ; a non standard type of comment that reads until a new line ; this should be EOL not 10 for portability : ./ 10 parse drop drop ; imm : count c@+ ; ; classic forth variables. ; The does> is a hack because there is a bug in using create in ; defining words. does> forces the >code point to be updated to 'here' : var create 0 , does> ; imm ; definition of CONSTANT : con create , does> @ ; imm ; the current default domain. This may have to be in bytecode ; because create needs to use it to set the domain ; jan 2019: the domain system is changing to a namespace system. ; var dom 1 dom ! ; a simple 'block' word that just reads block n into first buffer ; in a proper implementation this would use 'buffer' to flush ; code to disk and then read the block. Also, the block would only ; be read if it wasnt already loaded to ram (at 'first') ; ans blk variable var blk : block ; ( n -- A ) dup blk ! 2* block1 + 2 first read drop first ; ; The last block loaded. cryptic name because of disk block ; space limitations. var lb ; perhaps source and load should return a flag indicating ; success or failure. This may allow us to catch errors ; But have to dig down to "inputcompile" . : load ( n -- ) dup lb ! dup . block 1024 source ; ; get the loop counter, needed for thru, called I in ansi forth : ii r> r> r> dup >r swap >r swap >r ; ;: compile> wparse tick item, ; imm ; lookup a word and return the opcode or zero : op' wparse nfind xt>op ; imm ; use this op' in : defs : [op'] post op' post literal ; imm ; These words should be called op: and [op:] because ; comma words eg , c, get their argument from the stack ; not from the input stream. ; ; handy to compile an opcode by name eg: op: fcall ; this can be handy for opcodes that arent normally compiled. ; eg jump, jumpz, rloop etc ; we may also need code that compiles an opcode at runtime : op: wparse nfind xt>op c, ; imm ; use this in definitions ; This seems archane: And we need a simpler syntax ; for compiling FCALLs eg [call:] ; This is working! ; Another archane word. Compile an fcall to a word : [call:] post ['] ['] call, post call, ; imm ; more elaborate versions of [op:] ; : [op:] post op' post literal ' c, literal post call, ; imm ;: [op:] post [op'] ' c, literal post call, ; imm ; : [op:] post [op'] ['] c, post call, ; imm : [op:] post [op'] [call:] c, ; imm ; (run: limit start -- r: start limit ) ; (comp: -- 'here' ) ; At run-time: puts start and limit on return stack ; at compile time: marks a jump back address for loop etc ; the jump address is left on the data stack ; Source code do ;: do [op'] >r dup c, c, here ; imm ; The code below seems to be working. The phrase "[op:] >r" ; will compile the opcode ">r" when "do" runs (not when it ; compiles. So this is a little like a double "post" : do [op:] >r [op:] >r here ; imm ; compile >r >r to get loop parameters on the return stack ; and then leave jump-back position on the stack for "loop" to use. ; maybe (loop) could be ; : (loop) r> ( juggle return pointer ) ; r> r> ; // leave loop limit flag on the stack ; 1+ 2dup = ; // get rid of loop params if limit reached ; if swap drop swap drop fi ; // get all params back on the rstack ; swap >r swap >r swap >r ; ; for long jumps, we need to change the "jumpf" line to: ; [op:] jumpt 5 c, ; [op:] ljump ; as source ; : loop ; [op:] r> [op:] r> ; [op:] 1+ [op:] 2dup ; [op:] >r [op:] >r ; [op:] = ; [op:] jumpf ; here 1- - c, ; [op:] r> [op:] r> ; [op:] drop [op:] drop ; a "Forth Inc" word to load blocks x to y ; ( x y -- ) ... load blocks x to y ; here we need to chekc if x=y etc : thru ; ( a b -- ) ; there is no if yet!! ; 2dup = if 2drop exit fi swap do ii load loop ; ; load required blocks. These phrases (not defining a word) seem ; to get executed last, no matter where they are in the block. 1 20 thru clock ; load the shell block (defines shell and starts it) 33 load ; pad remainder of 1st disk block with zeros times 1*1024-($-block1) db 0 ; block1: ; like the old figforth variables. usage: 31415 var pi : Var create , does> ; imm ; standard forth comment : \ 10 parse drop drop ; imm ; This is working! ; Another archane word. Compile an fcall to a word : [call:] post ['] ['] call, post call, ; imm ; source version (shortjump limited to +/- 128 bytes) ; : again [op:] jump here 1- - c, ; imm ; source version (ljump long relative jumps) ; ( comp: jb -- ) ( run: -- ) ; jumps back at runtime. At compile time ; gets the absolute jump-back address from the data stack and compiles ; it a relative ljump. : again ; A (Address of compiled 'begin') ; compile "ljump" at current compile point [op:] ljump here ; A here 1- ; A here-1 /align to ljump instruction - ; A-here-1 ; compile relative ljump address (2 bytes) , ; imm ; compile an execution token, either as an opcode or else ; as an FCALL ; : xt, dup ['] nop 1+ < if , else ; ; Below a standard forth "if" word. Used to be in byte code. ; Need to use a jumpnz/ljump combination here ; ; compiles the "jumpnz" opcode and then a dummy relative ; jump address (+2). This address will be replaced with the ; real relative jump address when "fi" runs. ; I think I will have to use ljumps here to overcome the ; +/- 128 byte limit ; At runtime, if the value n on the stack is zero ' ; skip statements after this until next "fi" ' ; compiles a jumpzero and puts the current ' ; address on the data stack. The "fi" command consumes ' ; that address ' ; A new version of if using long jumps. This wont work until ; fi and else are adjusted to compile 2 byte target addresses. ; eg: jumpnz 4, ljump 2 ; where the "2" will be replaced by the real target when ; "else" or "fi" is encountered. The argument to ljump is 2bytes long : if ; ( runtime: n -- /ctime: -- A /compile a conditional long jump *) ; compile "JUMPNZ, 5". ;[op'] jumpnz c, [op:] jumpnz 5 c, ; compile "LJUMP, 2" ; The 2 (2 bytes will be replaced with a ; real target when "else" or "fi" executes. [op:] ljump ; Put current compilation position on the stack to be used ; by next "else" or "fi" here 2 , ; imm : else ; compile "LJUMP, 2". The 2 will be replaced by "fi" [op:] ljump ; leave H on stack for fi to use here ; temporary jump-to-fi target 2 , ; Aj H swap dup here ; H Aj Aj H swap - 1+ swap ! ; imm ; A new version of fi using long jumps ; run-time: ( -- ) compile-time: ( A -- ) ; At compile time obtains the correct jump ; address from the data stack and compiles the correct ; target address into a previously compile "if" clause. ; This word is called "then" in traditional forths. : fi dup here ; A A H swap - 1+ ; A H-A+1 swap ! ; imm ; just testing new if/else/fi ; : ff iff 65 emit eelse 64 emit ffi ; ; ) ; This defer cannot handle opcodes, which is not good. See ; another implementation of defer below. ; ; An alternative is to use a less elegant, but effective, method ; of actually compiling code into the word with "is" ; For an opcode we compile in OP, EXIT and for a normal word ; we compile FCALL,
, EXIT. op/exit is 2 bytes, and ; fcall/address/exit is 4 bytes. So deferred words will ; take up more room this way. ; standardish defer word. If the deferred word is not ; initialised then it should just do nothing. eg ; : defer create 0 , does> @ dup if pcall else drop fi ; imm : defer create 0 , does> @ pcall ; imm ; The "4 +" below is a cludge. In my implementation ; of does> the data field starts 4 bytes after the execution address. ; This is because "create" adds code to push parameter field address ; onto the stack, and does> then modifies that code. But there ; should be a more elegant way to do this. ; ; usage: ; defer all ' ls is all ; or: : print ['] printer is type ; ; Also, "is" should check that name and xt are valid : is ;( xt -- / set xt for to xt *) wparse nfind 4 + ! ; imm ; a new defer, to work with opcodes, compile a new name ; and then an exit and then allow 3 more bytes ; The -4 here+ should reset the code put in by "create" ; to push the data/parameter field address onto the stack. ; But there should be a more elegant way to do this, I think ; ; Another way is to define Defer with a buffer: ?? : defer create reset [op:] exit 0 , 0 c, code>here ; imm ; This is much more laborious than the "does>" style defer/is ; but is can handle opcodes, which is important I think. ; We dont have any good words for compiling ops/calls to ; any memory (only to "here/>code") eg: ; [op:mem] ( A -- ) etc ; either compile OP, EXIT or FCALL, address, EXIT : is wparse nfind ; XT xt swap dup ; xt XT XT xt>op dup if ; xt XT op swap drop ; xt op swap c!+ ; xt+1 else ; xt XT 0 drop swap ; XT xt [op'] fcall swap c!+ ; XT xt+1 !+ fi ; xt' [op'] exit swap c! ; imm ; allow us to use different versions of accept defer accept ' accept.byte is accept ; type a newline : cr 13 emit 10 emit ; : xt+ ; ( xt - xt' / get exec address of next word in dict *) 1- ; xt' n rcount drop 1- 1- ; xt'-2 @ ; ; ans standard tuck. This can be a handy way to save a value ; for later processing. Could be an opcode : tuck ( a b -- b a b ) swap 2dup drop ; ; get a copy of topmost return stack item. We need to dig ; under the word return pointer : r@ ; ( -- n ) ( R: n -- n ) r> r> dup >r swap >r ; ; just for testing long jump if ; : iff 0 if 60 emit fi ; ; see iff ; determine the used size of a block by searching for the 1st ; zero byte. Use like this: "first bsize" ; : bsize dup begin c@+ 0 = until swap - ; ; Increment a counter variable by 1 and leave the new value ; on the stack, because often we want to use the counter value ; immediately afterwards. This is like C ; nn++ (in forth: nn ++ ) : ++ ( A -- [A]+1 / increment counter *) dup dup @ ; A A n 1+ swap ; A n+1 A ! @ ; ; n+1 : -- ( A -- [A]-1 / minus 1 value at A *) dup dup @ 1- swap ! @ ; ; counter variables var nn var ll ;: ww. last @ ; begin dup .xt space xt+ dup 0 = until drop ; ; an implementation of the standard forth word 'I' which gets ; a copy of the loop counter onto the data stack. We have to ; 'dig' under the current word return pointer which is the ; current top of the return stack and also under the loop limit ; parameter ; : ii++ r> r> r> 1+ >r >r >r ; ; use this before 'exiting' from a do loop. : unloop r> r> r> drop drop >r ; ; discard loop parameters and continue execution after next 'loop' ; : leave ( -- ) ; ; just testing quote preprocessing by os.sed ; : quote char " char ' char " ; ;: [op:] wparse nfind xt>op literal c, ; imm ; pad remainder of 2nd block with zeros times 2*1024-($-block1) db 0 ; block2 ; 3rd disk block ; the last block for searching etc. var final 55 final ! ; parse and find words, more or less working ; : findwords term accept term count in0 ; begin ; wparse 2dup type space find dup u. space ; 0 = ; until ; ; frees a buffer (eg first) and writes old contents to disk if ; necessary. ;: buffer ( n -- adr //to do! ) ; : todo! nop ; ; logical not! same as 0= : not ( n -- f ) ; leave true [1] if n=0, else leave false [0] if 0 else 1 fi ; : 0= ( n -- f ) ; leave true [1] if n=0, else leave false [0] if 0 else 1 fi ; ; breaks out of one level of if/begin etc and jumps back to ; last begin. Preserves jump-back address for 'again' to use later. ; ( comp: jb JB -- jb JB ) ( run: -- ) ; this is not elegant because it fails if there are 2 levels of nesting. : continue [op:] jump 2dup drop ; jb JB jb here 1- ; jb JB jb here-1 - c, ; imm ; saves the current buffer (first) to block number n on disk : save ( n -- flag=-1/0/1 ) 2* block1 + 2 first write ; ; display all words in buffer ; : inwords term accept term count in0 ; begin ; wparse 2dup type cr ; 0 = ; until ; ; standard s" word : s" [char] " parse post sliteral ; imm ; An fcall will get compiled when ." is run, ; not when it is compiled. This is an important technique ; It is like a "double postpone" ; ; more elaborate versions of ." ... ;: ." post s" [ wparse type nfind ] literal post call, ; imm ;: ." post s" [ ' type ] literal post call, ; imm ;: ." post s" ' type literal post call, ; imm ;: ." post s" ['] type post call, ; imm : ." post s" [call:] type ; imm ; algorithm to convert BCD encoded values to binary (normal) ; binary = ((bcd / 16) * 10) + (bcd & 0xf) ; a colourful asci list. call with eg: 4 asc ;: asc 0 ; begin dup fg dup emit 1+ dup 255 = until drop ; ; a convenience to get rid of stuff on the stack : 2drop ( a b -- ) drop drop ; ; : 2drop dd ; : 4drop ( a b c d -- ) 2drop 2drop ; ; prints out time taken given 2 clock-ticks values (18/sec) on stack ; this has a limit of +/- 52 minutes. takes 2 double values ; ( D:t1 D:t2 -- ) : timer ; get rid of high clock value on stack drop swap drop swap - 55 u* u. ." milliseconds." cr ; ; do not change this word because it is being used to ; measure performance across different machines and different ; exec.x versions. : timeloop ( n -- ) ; juggle number of loops >r clock r> dup u. ." 000 loops" begin 1000 begin 1- dup 1 = until drop 1- dup 1 = until drop ." took " clock timer ; ; A new and improved "cmove" (see block 2) that is ; correct even when data areas overlap ; here use if A > B then copy from low to high ; but if B > A then copy from high to low. This will be used ; when the backspace key is pressed in an editor ; Actually! forth.inc forths use cmove and cmove> ; cmove> copies to overlapping address in higher memory. ; Having 2 words speeds up the copy. The programmer has to ; decide if the memory areas overlap and if the target is ; in higher mem. If so, use cmove> : cmove ( A B n -- / copy n bytes from A to B *) ; A B n ; If n==0 then crash out. dup 0 = if drop 2drop exit fi ; A B n >r 2dup ; A B A B r: n ; if A=B then nothing to do = if r> drop 2drop exit fi ; A B r: n 2dup < if ; A < B ; A B r: n r@ + 1- swap r@ + 1- swap ; A+n-1 B+n-1 r> 0 do ; A+n-1 B+n-1 ;>r c@- r> ; c@- >r dup c@ swap 1- swap r> ; A+n-1 c B+n ; this is c!- dup >r c! r> 1- ; A+n-1 B+n-1 loop 2drop else ; A > B this works for overlapping data areas ; A B r: n r> 0 do ; A B >r c@+ r> ; A+1 c B c!+ ; A+1 B+1 loop 2drop fi ; times 3*1024-($-block1) db 0 ; start block3: ; a dodgy opcode test based on being less than the xt of "nop" ; in the future this will not be true because new opcodes can ; be added to the system, probably in their own namespace/wordlist. ; just an alias for xt>op : opxt? ( xt -- F ) xt>op ; ; The simplest dotxt version ; : .xt ( A -- / print wordname of xt *) ; 1- rcount type ; : .xt ( A -- / xt name with colours for opcodes/immediate/words *) dup 0= if 13 fg ." [xt:null=0]" 7 fg drop exit fi ; light blue for normal words 11 fg ; Immediate words are red dup imm? if 12 fg fi ; here make word xt>op which leaves flag ; Opcodes are brown dup opxt? if 6 fg fi 1- rcount type ; return colour to normal 7 fg ; ; if0 based on new long jump if. : if0 [op:] jumpz 5 c, [op:] ljump here 2 , ; imm ; can make a simple alias for this immediate word like : ifnot post if0 ; imm ; this conserves the current base : .hex ( n -- / display top-of-stack as unsigned hexadecimal *) base c@ swap 16 base c! u. ; restore original base base c! ; ; fill u bytes of memory with 0 starting at addr : erase ( A u -- ) 0 do 0 c!+ loop drop ; ; fill u bytes of memory with byte b starting at addr : fill ( A u b -- ) swap 0 do dup c!+ loop drop drop ; ; display u words of data : dumpw ( A u -- ) ; print mem address swap dup u. ." : " swap 0 do @+ u. space loop drop ; : dumpw ( A u -- / display u words of data *) ; A u 0 do ii ; A ii ; print memory address and newline every 8 chars 8 mod if0 cr 11 fg dup u. ." :" 15 fg fi ; A @+ u. space ; A+2 loop drop ; ; allocate u bytes of data-space, beginning at the next available ; location. Normally used immediately after "create". : allot ( n -- ) here + here! ; ; allot data space and initialize to 0 : allot0 ( n -- ) here swap 2dup erase + here! ; ; create a data buffer in the dictionary of n bytes : buffer: ( n -- ) create allot0 does> ; imm ; convert from n to cells (in this case 2 bytes) : cells ( n -- ) 2* ; ; find out how many bytes are free in source block n : bfree ( n -- free ) block dup ; adr adr begin c@+ 0 = until ; adr adr+x swap - 1024 swap - ; ; 1024-x ; print some machine info ;: mach ( -- ) ; machine count 2dup ." name: " type cr ; + count ." signature: " type cr ; ; print the machine name : mname ( -- ) machine count type ; times 4*1024-($-block1) db 0 ; block4: ; gforth "fi" ; : endif post fi ; imm ; standard forth then : then post fi ; imm ; put a space on the stack : bl 32 ; ;." FORTH-style system" cr ;." 'ls' to see words." cr : 3drop 2drop drop ; ; an old synonym for negate : minus neg ; : negate neg ; : here+ ( n -- ) here + here! ; : abs ( n -- +n / absolute value of n *) dup 0 < if negate fi ; ; true if x >= y otherwise false : >= ( x y -- true=1/false=0 ) < not ; ; simplest ? : > swap < ; : <= 2dup < if drop drop 1 exit fi = ; ; tests if string at A (length n) starts with string at P (length m) : prefix ( A n P m -- true=1/false=0 ) swap >r 2dup ; A n m n m P ; if length of string < prefix then false < if r> 4drop 0 exit fi ; A n m r: P swap drop r> swap ; A P m ncompare ; ; 0=false=different ; a double swap, needed for double numbers and convenience. : 2swap ( a b x y -- x y a b ) >r swap ; a x b r: y >r swap ; x a r: y b r> r> swap ; x a y b >r swap ; x y a r: b r> ; ; what you would expect : 4dup ; a b c d >r >r 2dup ; a b a b r: c d r> r> 2dup >r >r ; a b a b c d r: c d 2swap ; a b c d a b r: c d r> r> ; ; Actually the code below should return (A n 0) if the ; string is not found, but it is not doing this. ; standard form : search ( A n P m -- A' m flag / search for text in a string ) ; A n P m begin 2swap dup 0 = ; P m A' n' flag .. n==0 so no more string to search ; A n false (original string, length flag) if 2drop 0 exit fi 2swap ; A' n' P m swap >r 2dup ; A' n' m n' m r: P ; if length of string < substring then leave A n false < if ; A' n' m r: P 2drop r> drop ; A' 0 0 ; A' 0 0 exit fi ; A' n' m r: P r> swap 4dup ; A' n' P m A' n' P m prefix ; A' n' P m flag ; return: (found address, length, true) if prefix is true if ; A' n' P m swap drop ; A' n' m swap drop 1 ; A' m 1 exit fi ; A n P m >r >r ; A n r: m P 1- swap 1+ swap ; A+1 n-1 r> r> ; A+1 n-1 P m again ; ; 0=false=different times 5*1024-($-block1) db 0 ; block5 ; ans 94 forth word ; return true != 0 if a <= n < b, otherwise return false==0 ; notice r >r dup r> 1- swap ; n a-1 n < swap ; t/f n r> < ; t/f t/f and ; : xyemit ( c x y -- / print char c at [x,y], reset pos *) getxy 2swap atxy ; c x y >r >r emit r> r> atxy ; : dump ( A n -- / display n bytes of memory *) ; A n 0 do ; A' ; print 12 bytes per line ii 12 mod 0 = if cr dup 6 fg .hex [char] : emit 3 fg fi c@+ dup ; A+1 c c .hex ; A+1 c ; if not printable, just print "." dup 32 127 within ; A+1 c F 0 = if drop [char] . fi getxy swap drop ; A+1 c y ; calculate cursor position for asci chars ii 12 mod 60 + ; A+1 c y [ii mod 12]+50 swap 14 fg xyemit 3 fg space loop cr ; ; search for all words in the dictionary starting ; with prefix. Improved logic with 2swap. ; search for all words in the dictionary containing ; a string. Improved logic with 2swap. Replace "search" ; with "prefix" to only see words starting with string ; If a word is immediate, display it "red", if a word is ; an opcode, display it "brown" : s/ ( -- ) ; initialise counter 0 nn ! wparse 2dup ; P m P m last @ ; P m P m A begin dup >r ; P m P m A r: A 1- rcount ; P m P m S n r: A 2swap ; P m S n P m r: A search ; P m S' m flag r: A ; Discard the found address and length >r 2drop r> ; P m flag r: A if ; print words 8 to a line nn ++ 8 mod 0 = if cr fi ; display the name of the word r> dup .xt space >r fi ; P m r: A 2dup r> ; P m P m A xt+ dup ; P m P m A+ A+ 0 = until 4drop drop ; imm ; do defined as source. ; : do [op'] >r dup c, c, here ; imm ; need to compile code which checks something : ?do [op'] >r dup c, c, here ; imm ; : (?do) ... ; ; try a word that types one line ; eg ltype ( A n -- A' n' ) ; source version of type, ignore asci 13 in source but emit ; a 13 when 10 found : type ( A n -- ) ; string length is 0 so do nothing dup 0 = if 2drop exit fi 0 do c@+ ; A'+1 n ; ignore \r = asci 13. Below we use the trick of putting ; a dummy 0 on the stack to get an if/elseif/elseif/fi effect dup 13 = if drop 0 fi dup 10 = if drop 0 cr fi dup if emit else drop fi loop drop ; times 6*1024-($-block1) db 0 ; like unix "disk free" : df ( -- ) 45 0 ." Free bytes by block: " cr do ii dup 6 fg u. [char] : emit 10 fg bfree u. ." " ; print 4 to a line ii 4 mod 3 = if cr fi loop ; ; compute the nth fibonacci using recursion : fib ( n -- fib[n] ) dup 1 swap < if 1- dup 1- fib swap fib + fi ; ; Testing tick by accepting input and ; db ' displaying the found execution token : try.tick begin term accept term count dup 0 = if exit fi tick ./ 0/n/op.xt flag=0/1/2/3 cr .s cr again ; ; the opposite of xt+, finds the previous definition in ; the dictionary, so goes in the opposite direction from ; the linked list. : xt- ( xt -- prev.xt ) last @ ./ xt last begin ./ xt a dup ./ xt a a >r ./ xt a r: a xt+ ./ xt a+ r: a 2dup ./ xt a+ xt a+ r: a = ./ xt a+ T/F r: a if ./ xt a+ r: a drop ./ xt drop ./ r> ./ a exit ./ a fi r> ./ xt a+ a drop ./ xt a+ dup ./ xt a+ a+ 0 = ./ xt a+ true/false until ; ; show the compiled size (in bytes) of a word ; Do an rcount first : wsize ; xt dup 1- ; xt xt-1 rcount ; xt A n drop swap ; A xt xt- ; A xt' 1- rcount drop ; A B ; 2 - swap - 1- ; ; B-A-1 : size ( show word size ) wparse nfind dup if0 drop ." ?" else wsize ." (bytes): " . fi ; imm times 7*1024-($-block1) db 0 ; in most forths base in word, not char : bin ( -- / set numeric base to binary *) 2 base c! ; : hex ( -- / change base to hexadecimal 16 *) 16 base c! ; : deci 10 base c! ; ; print the stack with signed numbers, source version ; display the items on the data stack without ; altering it. The top (or most recent) item ; is printed rightmost : .s ( -- ) depth 0 = if exit fi depth ; ... n n begin swap >r depth 1 = until ; ... n r: .... begin r> dup ; n a a . space swap ; a n 1- dup 0 = ; a n-1 n-1 until drop ; ; display u bytes of data, better than dump : dumpx ( addr u -- ) ; print mem address ; A u 0 do ; swap dup u. ." : " swap ii ; print memory address and newline every 8 chars ; A ii 8 mod not if cr 11 fg dup u. ." :" 15 fg fi ; A c@+ u. space ; A+1 c loop drop nop ; ; the escape keycode : esc ( -- n ) 27 ; ; move cursor up one row (check for zero) : cur.up getxy 1- atxy ; ; move cursor down one row : cur.down getxy 1+ atxy ; ; move cursor left one (need to check for zero) : cur.left getxy swap 1- swap atxy ; ; move cursor right one : cur.right getxy swap 1+ swap atxy ; ; move the cursor around with arrow keys : arrow ; a video mode with a cursor 3 vid ." arrow keys!! q to exit " cr begin ekey 1 = if dup 72 = if cur.up fi dup 75 = if cur.left fi dup 77 = if cur.right fi dup 80 = if cur.down fi drop else [char] q = if 16 vid exit fi fi again ; ; reset the video mode ; make an asci box n wide, eg: 7 box ; : ascline begin 196 emit loop ; 179 side : box ( n -- ) 218 emit dup 1 do 196 emit loop 191 emit cr 192 emit dup 1 do 196 emit loop 217 emit ; ; returns the lowest number of "a" and "b" : min ( a b -- min ) 2dup < if drop else swap drop fi ; times 8*1024-($-block1) db 0 : all ( n -- / load blocks from last block >> n *) ; lb is the last block loaded with "load" lb @ 1+ swap 1+ ; a+1 n+1 thru ; ; just display the current disk geometry parameters which ; will be used for reads and writes from and to disk (usb etc) : geom ( -- ) ." boot drive: " drive c@ u. cr ." sectors per track: " sectors @ u. cr ." sides (platters): " sides @ u. cr ; ; on different systems (slower, faster) the mswait needs ; to be adjusted. Perhaps there is a way to auto adjust with ; clock etc ; on qemu asus seems about right var mswait 950 mswait ! ; standard forth : ms ( n -- / wait n milliseconds *) 0 do mswait @ 0 do nop loop loop ; ; list all words in the dictionary : ls ( -- / list words in dictionary *) last @ ; number of words 0 nn ! ; keep track of number of lines 0 ll ! begin ; print 8 words to a line nn ++ 8 mod 0 = if cr ; print a prompt every 22 lines ll ++ 22 mod 0 = if 1 fg [char] > emit key ; quit if 'q' pressed [char] q = if exit fi 0 bg cr fi fi dup .xt space xt+ dup 0 = until drop ; ; get the next insertion point in the counted string A after A+i or ; just return A A+i if already at the last insertion point. ; The last insertion point is one character after the last char ; in the string : nextc ( A A+i -- A A+i' / next char, insert in string *) 2dup swap - >r ; A A+i r: i ; check the count over c@ 1 + r> ; A A+i n+1 i swap < ; A A+i flag (ir >r dup r> = ; f r: b if r> drop drop -1 exit fi r> = ; times 9*1024-($-block1) db 0 ; not a standard forth word, as far as I know. ; Makes copying/initialising strings a bit easier : smove ( A n B -- / copy n chars from A. Store counted string at B *) >r dup ; A n n r: B r> c!+ ; A n B+1 swap cmove ; ; what you would expect : 3dup ( a b c -- a b c a b c *) ; a b c >r 2dup ; a b a b r: c r@ swap ; a b a c b r: c >r swap ; a b c a r: c b r> r> ; : @- ( A -- A-2 c / like @+ *) dup @ swap 2 - swap ; : c@- ( A -- A-1 c / like c@+ *) dup c@ swap 1- swap ; : c!- ( c A -- A-1 / like c!+ *) dup >r c! r> 1- ; ; this version just prints until the next newline or max n chars ; Another version could use "startline" above to print whole line : typeline ( A n -- /print line containing addr A *) 0 do c@+ ; A'+1 c dup 13 10 of2 if ; A'+1 c 2drop unloop exit fi emit ; A'+1 loop drop ; : append ( A n B -- / append n chars from A to counted string at B *) ; append characters at the end of B count ; A n B+1 m 4dup ; A n B+1 m A n B+1 m + ; A n B+1 m A n B+1+m swap cmove ; Now increment the count at B ; A n B+1 m swap 1- >r ; A n m r: B + r> ; A n+m B c! drop ; ; search source code blocks for a word : ss/ ( -- / search blocks for a phrase *) ; get the whole line, not just a word ; actually, when interactive there is no newline 10 ; char, but parse will advance to the end of the input ; anyway. There is a bug in "parse" at the moment which ; cuts a character. see bugs 10 parse ." Searching for " ; white, yellow, white 14 fg 2dup type 7 fg ." on disk... " cr cr ; forground bright white 15 fg ." Block Text " cr ." ----- ---- " cr ; A n ; "final" has the last source code block final @ 0 do ; A n 2dup ; A n A n ii block 1024 ; A n A n B 1024 2swap search ; A n B' n flag if ; A n B' n ; just assume lines are < 80 chars drop 80 ; A n B' 60 ; green text 10 fg ii . [char] > emit ; purple text 13 fg space typeline cr else ; A n B' n 2drop fi loop ; A n 2drop ; dull white text 7 fg ; imm ; return n if ab : limit ( n a b -- n/a/b ) >r min r> max ; times 10*1024-($-block1) db 0 24 buffer: defterm ; modify this to display the source code for ; Puts -1 on the stack if not found ; A similar word is called "locate" in many forths. : defblock ( A n -- n / find 1st definition block of word at A/n *) ; add a colon before the search word s" : " defterm smove ; append the search word after the colon in "defterm" ; A n defterm append defterm count ; A n 30 0 do ; A n 2dup ; A n A n ii block 1024 ; A n A n B 1024 2swap search ; A n B' n flag if ; A n B' n 4drop ii ; ii unloop exit else 2drop ; A n fi loop 2drop -1 ; : lo ( -- / loads all blocks until *) wparse ; A n defblock ; x ( block containing first definition of or -1, not found) ; check if -1 dup -1 = if drop ." not found" cr exit fi ; now load all blocks upto and including required block all ; imm ; display byte value of K value : K 1024 u* ; ; called I' in some forths (ron geere) : iimax ( -- n / get a copy of loop limit *) r> r> dup >r swap >r ; ; a word that types one line. What should we do with ; unprintable characters? Print a '?' Also, what happens ; to the remnant 13,10 ? : typeline ( A n -- A' n' /type one line of input) 0 do c@+ dup emit 13 = if ii iimax swap - unloop exit fi loop 0 ; ; we can just count 13,10 chars and pause when they reach ; a certain number. Also, its better to ignore asci 13 : page ( A n -- / page string at A length n *) ; initialise newline counter 0 nn ! ; if string length = 0 do nothing dup if0 2drop exit fi 0 do ; A c@+ ; A'+1 n ; ignore \r = asci 13. Below we use the trick of putting ; a dummy 0 on the stack to get an if/elseif/elseif/fi effect dup 13 = if drop 0 fi dup 10 = if drop 0 cr nn ++ 20 mod 0= if 10 fg ." ..." 7 fg key [char] q = if unloop exit fi cr fi fi dup if emit else drop fi loop drop ; ; displays block n on the screen. : list ( n -- /display block n on screen *) 10 fg ." Listing Block " dup . 7 fg ." (1024 bytes)" cr block 1024 page ; times 11*1024-($-block1) db 0 ; list all opcodes (=< NOP which is the last in the table) : ops [op'] nop 1+ 1 do ii 8 mod 0 = if cr fi ii dup 6 fg u. [char] : emit 3 fg .code space loop ; ; A Minimalistic "see" ; : see wparse tick drop ..word ; imm ; a standard (?) word to see a word decompilation : see ( ) wparse 2dup ; A n A n tick ; A n A [0/1/2/3] dup 0 = if 2drop type ." ??" cr exit fi dup 1 = if 2drop type ." (number)" cr exit fi dup 2 = if 2swap type drop ." opcode=" u. cr exit fi ; A n xt 3 2swap 2drop ; xt 3 drop ..word ; imm ; db ' flag=0 not number nor word ' ; db ' flag=1 if number, 2 if opcode, 3 if procedure ' ; duplicate TOS if non-zero : ?dup dup 0 = if exit else dup fi ; ; a recursive greatest common divisor word ; from r.v.noble : gcd ( a b -- gcd / greatest common divisor *) ?dup if tuck mod gcd fi ; : startline ( A B -- B' /leave address of start of line/string *) begin ; error! B cannot be < A 2dup swap < if swap drop exit fi ; exit if B=A (already at start of string) 2dup = if swap drop exit fi ; A B' c@- ; A B'-1 c 13 10 of2 if ; A B'-1 2 + swap drop ; B'+1 exit fi again ; ; a simple approx * 10K : pi 31415 ; ; recursive factorial. very succint in forth ; 16bit forth can only hold 8! no more : fact dup 1 = if exit fi dup 1- fact u* ; ; recursive arithmetic series : arith dup 1 = if exit fi dup 1- arith + ; ; this could/should be a constant : 10K 10000 ; ; calculate E exponent using infinite series and factorial ; we can only loop upto 8 because this is a 16 bit forth. ; accurate to 2 decimal places. All is scaled by 10K : Ecc 10K 8 1 do 10K ii fact / + loop ; ; exponential e * 10K : E 27182 ; ; e == 1 + 1 + 1/1*2 + 1/1*2*3 + ... ; golden ratio phi (1 + 5^1/2)/2 * 10K : phi 16180 ; ; This square root method is very cool and gets a good ; approximation within about 6 or so iterations. ; gets the next approximation to the square root, from ron geere. ; based on newtons method : approx ( n x -- n x' ) over over / + 2 / ; ; return b, the approximate square root of a (maximum 32767 if the / ; division operator is signed, or else 64K if not), ; this just does the iterations of the "approx" word. : sqrt ( a -- b ) 60 5 0 do approx loop swap drop ; times 12*1024-($-block1) db 0 : s+c ( c A -- append char c to counted string A *) dup c@ ; c A n 1+ over c! ; c A dup c@ + c! ; ; deletes the last word in the dictionary by regressing 'last' ; and moving back the >code compile pointer to the end of the ; previous word : del ( -- ) last @ 1- rcount drop 2 - >code ! last @ xt+ last ! ; 50 buffer: wordname ; wordname 2 swap c!+ 58 swap c!+ bl swap c!+ ; todo! add ": " infront of search term. Print until next ";" : showdef ( /shows source definition for word *) wparse ; A m 14 fg 2dup type 15 fg ; [char] " ." source code.. " cr ; A n 30 0 do ; A n 2dup ; A n A n ii block 1024 ; A n A n B 1024 2swap search ; A n B' n flag if ; A n B' n ; just assume lines are < 80 chars drop 200 ; A n B' 60 ; green text 10 fg ii . [char] > emit ; purple text 13 fg space type cr else ; A n B' n 2drop fi loop ; dull white text 7 fg ; imm ; create a list data type (an array of 16bit cells with length ; and capacity). At run time, put reference on stack to the first ; byte of the data structure : list: ( comp: n -- ) ( run: -- addr ) create dup , 0 , cells allot0 does> ; imm ; addr is a reference to a list: object ; check if the list is full (i.e. size==capacity) : li/full ( addr -- flag=t/f ) @+ swap @ = ; ; check if the list is empty : li/empty ; ( addr -- flag=t/f ) 2 + @ 0 = ; ; increment list size by 1. But all these words may degrade ; performance. : li/incr ( addr -- ) 2 + dup !1+ ; ; delete last element by decreasing list size : li/del ( addr -- ) 2 + dup ./ a+2 a+2 @ 1- swap ! ; ./ a ; initialize the list ; delete all elements, set size (not capacity) to 0 : li/0 ( addr -- ) 2 + 0 swap ! ; ; return the list size : li/size ( addr -- n ) 2 + @ ; ; add a new element to the list and increment size ; use: 5 obj li/add : li/add ( n addr -- ) dup li/full if drop drop exit fi tuck 2 + @+ ./ a n a+4 len 2* + ! ./ store new element. 2 + !1+ ; ./ increment size times 13*1024-($-block1) db 0 : c++ ( A -- A / incr byte value stored at A *) dup dup c@ ; A A n 1+ swap c! ; : c-- ( A -- A / decr byte value stored at A *) dup dup c@ 1- swap c! ; : spaces ( n -- / type n spaces *) begin space 1- dup 0 = until drop ; ; an asci block char. : ablock 219 ; ; print n coloured blocks : glow ( n -- / print n coloured blocks *) begin dup fg 219 emit 1- dup 1 = until drop ; ; an asci table : asci ( -- / show a table of asci chars *) 1 begin dup u. space dup emit space 1+ dup 255 = until drop ; ; list elements : li/ls ( addr -- ) dup li/empty if ." " drop exit fi dup li/size ./ a size swap 4 + swap 0 ./ a+4 size 0 do @+ u. space loop drop ; ; list elements as opcodes : li/ops ( addr -- ) dup li/empty if ." " drop exit fi dup li/size ; a size swap 4 + swap 0 ; a+4 size 0 do @+ .code space loop drop ; ; list elements as calls : li/calls ( addr -- ) dup li/empty if ." " drop exit fi dup li/size ; a size swap 4 + swap 0 ; a+4 size 0 do @+ .xt space loop drop ; times 14*1024-($-block1) db 0 ; see if list has element n : li/has ( n A -- F ) dup li/empty if 2drop 0 exit fi swap >r ; a r: n dup r> swap ; a n a dup li/size ; a n a size swap 4 + swap 0 ; a n a+4 size 0 do ; a n a+4 @+ swap >r ; a n m r: a+x >r dup r> ; a n n m r: a+x = if r> 2drop drop 1 unloop exit fi r> ; a n a+x loop 2drop drop 0 ; ; add an element only if list doesnt already contain element : li/addu ( n addr -- ) 2dup li/has ./ n A t/f if drop drop exit fi li/add ; ; Using a background color cursor ; Modified ctype to display multiline strings. But ; the \r \n characters make the screen scroll, when xy is near ; the bottom of the screen ; Make ctype responsible for showing itself. So add x y params ; on stack and eliminate showbuffer. This will allow us to ; have a margin on multiline text. This is used by accept and ; by edit (or will be) : ctype ( A A+i -- / show string at A with cursor at i *) swap count ; A+i A n dup 0 = if drop 2drop ; print a block cursor at the end of the string too. ; 4 fg 254 emit 7 fg ; green background colour cursor 2 bg space 0 bg exit fi ; A+i A n ; set normal colour to white 7 fg 0 do ; A+i A' ; print green background block cursor 2dup = if 2 bg fi c@+ ; A+i A'+1 c ; ignore \r = asci 13. Below we use the trick of putting ; a dummy 0 on the stack to get an if/elseif/elseif/fi effect dup 13 = if drop 0 fi dup 10 = if drop 0 cr ; clear the next line getxy 60 spaces atxy fi dup if emit else drop fi ; back to normal background colour 0 bg loop ; A+i A' = if 2 bg space 0 bg fi ; ; inserts character c in counted string A at the insertion ; point A+i. This could handle 13,10 newlines as well : insert ( A A+i c -- A A+i+1 /insert char in string *) ; change \r (13) to \n (10) since this system uses unix line endings dup 13 = if drop 10 fi ; first increment the count >r >r c++ r> ; A A+i r: c 2dup - >r ; A A+i r: c i over c@ r> ; A A+i n i r: c ; If the insertion point is after the last character in the ; string, then all we have to do is copy the character in. < if ; A A+i r: c r> swap c!+ ; A A+i+1 ; count at A already incremented, nothing else to do exit fi ; now the real work: copy string after A+i 1 char right ; A A+i r: c 2dup - >r ; calculate how many chars need to be moved right ; A A+i r: c i over c@ 1+ r> - ; A A+i n+1-i r: c >r dup dup 1+ r> ; A A+i A+i A+i+1 n+1-i r: c cmove ; now store the char in its place in the string ; A A+i r: c dup r> swap c! ; A A+i 1+ ; ; delete one character from the counted string at A or do ; nothing if i=1 : delchar ( A A+i -- A A+i' /delete 1 char in string, or not *) ; do nothing if i==1 (at first character) 2dup swap - 1 = if exit fi ; first decrement the count ; A A+i swap c-- swap ; A A+i 2dup - >r ; Calculate how many chars need to be left shifted ; A A+i r: i over c@ 1+ r> - ; A A+i n+1-i >r dup dup 1- r> ; A A+i A+i A+i-1 n+1-i cmove ; A A+i 1- ; times 15*1024-($-block1) db 0 ; leave the value (not pointer) on the stack : n++ ( A n -- [A]+n ) swap dup @ ; n A m swap >r + dup r> ; n+m n+m A ! ; ; check if opcode : op? ( n -- F / is n an opcode or not? *) 0 [op'] nop 1+ within ; ; get a unique list of dependencies for a word ; will have to follow unconditional jumps to their target. 50 list: dep.oo 50 list: dep.cc : deps ( xt -- / show dependencies for a compiled word ) ; there is a bug because wsize doesnt work for the ; last word, need to check the last variable ; Another bug is that wsize includes the name of the ; word. So we need "wbytes" which is just the compiled ; byte size. dup dup wsize + swap ./ xt+size xt begin c@+ dup ./ end A+1 n n op? ./ e A+n op flag ;if drop drop drop exit fi ./ bail if not an opcode if dup dep.oo li/addu space ./ end A+n op ;dup .code fi ; check here if it is an unconditional jump, and jump there ; if an fcall get the xt and recurse dup [op'] fcall = if drop dup 2 + swap ./ end A+n+2 A+n @ ./ E A+x xt :get fcall xt ;dup dep.cc li/addu ;dup ;." <" .xt ." > " ;deps ./ recursive! else args + ./ end A+x fi 2dup < until drop drop ; ; finds dependencies, initializes the arrays and calls deps : Deps ( -- ) wparse tick drop dep.oo li/0 dep.cc li/0 deps cr 11 fg ." opcodes: " 15 fg dep.oo li/ops cr 11 fg ." words: " 15 fg dep.cc li/calls ; imm ; another version of 2= using 'and' logic, 7 ops versus 13 for 2= ; This shows how to use and logic to replace if statements. : d= ( a b A B -- -1:true, 0:false ) swap >r = ; a flag(-1:true,0:false) r: A swap r> ; t/f a A = ; t/f t/f and ; times 16*1024-($-block1) db 0 : tmode ( text mode ) 3 vid ; : vmode ( video mode ) 16 vid ; : nip ( a b -- b ) swap drop ; ; the simplest random number, but only works approx 1/second : rnd ( -- n / random number mod 16 *) clock drop 16 mod ; ; a forth inc very simple random generator ( simple random number generation -- high level ) var seed ; or use here... here rnd ! clock drop seed ! : rand seed @ 31421 * 6927 + dup seed ! ; : random ( u -- u' / random # between 0 and u *) rand um* nip ; ; returns true if ekey is a left arrow : arrow< ( n 0/1 -- flag ) 75 1 d= ; ; returns true if ekey is a right arrow : arrow> ( n 0/1 -- flag ) 77 1 d= ; : bs 8 emit ; ; this displays a buffer A at a particular point x y on the ; screen with the cursor positioned at [x+i, y]. ; [A] contains the length of the string and "i" is the insertion ; point as an offset from A. "i" must be > 0. ; This will be called after every keystroke in acceptx to display ; the state of the buffer. : showbuffer ( x y A A+i -- /shows buffer A at x,y *) ; x y A A+i 2swap 2dup atxy ; A A+i x y 80 spaces atxy ; A A+i ctype ; ; A new version of accept that can edit with the arrow keys. ; No character limit ; Count, buffer and insertion point A+i are updated with every ; keystroke, so we dont need A+n on the stack, nor A+1 : accept.arrow ( A -- / get typed edited text into buffer A *) ; initialise buffer to nothing 0 over ! ; hide the text cursor, its annoying 6 7 cursor ; "getxy" to saves the initial screen position ; A dup getxy 2swap 1+ ; x y A A+i (where A points to count byte) begin ; x y A A+1 ; for debugging ; getxy >r >r 0 22 atxy ." count:" swap dup c@ . swap r> r> atxy ; getxy >r >r 0 23 atxy ." stack:" .s r> r> atxy ; x y A A+1 4dup showbuffer ; x y A A+1 ekey ; x y A A+i k flag ; extended keys (eg: arrows, page-up/down etc) have flag=1 if ; x y A A+i k ; up arrow ; for single line editing, use up arrow to set ; insert point to beginning of line dup 72 = if ; x y A A+i k 2drop dup 1+ 0 ; x y A A+1 0 fi ; x y A A+i k ; down arrow ; for single line editing, use down arrow to set ; insert point to end of line dup 80 = if ; x y A A+i k 2drop dup count + 0 ; x y A A+1+n 0 fi ; left arrow dup 75 = if ; x y A A+i k ; cls drop prevc 0 ; x y A A+i' 0 fi ; right arrow dup 77 = if ; x y A A+i k drop nextc 0 fi ; cr ." stack: " .s cr drop ; x y A A+i+1 else ; x y A A+i k ; now handle normal keys and characters dup 13 = if ; reshow the cursor 7 6 cursor drop 4drop exit fi ; x y A A+i k ; backspace key dup 8 = if ; x y A A+i k ; delchar handles all cases drop delchar ; x y A A+i else ; No emit! because "showbuffer" does that. ; x y A A+i k insert ; x y A A+i+1 fi fi ; if extended or normal char ; x y A A+i again ; ; make backtick ` put a newline 13,10 in the buffer ; for testing ;dup 96 = if ; drop ; 13 insert 10 insert 0 ;fi times 17*1024-($-block1) db 0 ; But this below is not the simplest. We can write an ; accept with no backspace editing. ; eg: : accept.0 ... ; A simple source version of "accept", with no character limit, ; no special keys, only editing with backspace : accept.basic ( a -- / get text into buffer *) dup 1+ dup ; A A+1 A+1 begin key dup ; A A+1 A+n k k 13 = if drop swap - swap c! exit fi dup ; test if it is a backspace 8 = if ; start of buffer? drop 2dup < if bs space bs 1- fi continue fi dup emit ; A A+1 A+n k swap c!+ ; A A+1 A+n+1 again ; ; if we dont have anything better, just use this ' accept.basic is accept ; an editor. This uses the same strategy as accept.arrow but ; hopefully will be able to edit multiline text. newlines are \n ; asci 10 ; No character limit ; Count, buffer and insertion point A+i are updated with every ; keystroke, so we dont need A+n on the stack, nor A+1 : edit ( A -- / get typed edited text into buffer A *) todo! ; hide the flashing default cursor. 6 7 cursor ; "getxy" to saves the initial screen position ; A dup getxy 2swap 1+ ; x y A A+i (where A points to count byte) begin ; x y A A+1 ; for debugging ; getxy >r >r 0 22 atxy ." count:" swap dup c@ . swap r> r> atxy ; getxy >r >r 0 23 atxy ." stack:" .s r> r> atxy ; x y A A+1 4dup showbuffer ; x y A A+1 ekey ; x y A A+i k flag ; extended keys (eg: arrows, page-up/down etc) have flag=1 if ; x y A A+i k ; up arrow ; for single line editing, use up arrow to set ; insert point to beginning of line dup 72 = if ; x y A A+i k 2drop dup 1+ 0 ; x y A A+1 0 fi ; x y A A+i k ; down arrow ; for single line editing, use down arrow to set ; insert point to end of line dup 80 = if ; x y A A+i k 2drop dup count + 0 ; x y A A+1+n 0 fi ; left arrow dup 75 = if ; x y A A+i k ; cls drop prevc 0 ; x y A A+i' 0 fi ; right arrow dup 77 = if ; x y A A+i k drop nextc 0 fi ; cr ." stack: " .s cr drop ; x y A A+i+1 else ; now handle "normal" keys and characters ; x y A A+i k ; insert should handle cr/lf ; make [esc] exit the editor for now dup 27 = if ; reshow the cursor 7 6 cursor drop 4drop exit fi ; x y A A+i k ; backspace key dup 8 = if ; x y A A+i k ; delchar handles all cases drop delchar ; x y A A+i else ; No emit! because "showbuffer" does that. ; x y A A+i k insert ; x y A A+i+1 fi fi ; if extended or normal char ; x y A A+i again ; times 18*1024-($-block1) db 0 ; buffers for holding previous commands and a temp ; string. This will allow the up and down arrows to recall ; a previous command. Also, we could only create these ; variables if they dont exist already. 80 buffer: h1 80 buffer: h2 80 buffer: temp ; These different versions of accept can be vectored to ; "accept" with "defer accept ' accept.hist is accept" ; This is nice because it allows the user to change the behaviour ; of the system. ; ; A version of accept that has command history and allows ; editing with arrow keys. The up arrow recalls previous text : accept.hist ( A -- / get typed text into buffer A with history *) ; initialise buffer to nothing ; actually the shell should probably set this to 0, not here. 0 over ! ; A ; set history to null ?? ; 0 h1 ! 0 h2 ! 0 temp ! ; hide text cursor 6 7 cursor ; "getxy" saves the initial screen position ; A dup getxy 2swap 1+ ; x y A A+i (where A points to count byte) begin ; x y A A+1 ; for debugging ; getxy >r >r 0 22 atxy ." count:" swap dup c@ . swap r> r> atxy ; getxy >r >r 0 23 atxy ." stack:" .s r> r> atxy ; x y A A+1 4dup showbuffer ; x y A A+1 ekey ; x y A A+i k flag ; extended keys (eg: arrows, page-up/down etc) have flag=1 if ; x y A A+i k ; up arrow ; for single line editing, use up arrow to recall previous ; command dup 72 = if ; copy buff->temp, h1->buff, h2->h1, temp->h2 ; x y A A+i k 2drop ; x y A dup count temp ; x y A A+1 n B ; copy buff->temp smove ; x y A ; copy h1->buff dup >r h1 ; x y A H1 r: A count r> ; x y A H1+1 n A smove ; x y A ; copy h2->h1 h2 count h1 smove ; copy temp->h2 temp count h2 smove ; x y A ; move to first character of buffer dup 1+ 0 ; x y A A+1 0 fi ; x y A A+i k ; down arrow ; use down arrow to recall new command dup 80 = if ; x y A A+i k 2drop ; x y A ; copy h2->temp, h1->h2, buff->h1, temp->buff ; downarrow ; copy h2->buff h2 count temp smove ; x y A h1 count h2 smove ; x y A dup count h1 smove ; x y A dup >r temp count r> smove ; x y A dup count + 0 ; x y A A+1+n 0 fi ; left arrow dup 75 = if ; x y A A+i k ; cls drop prevc 0 ; x y A A+i' 0 fi ; right arrow dup 77 = if ; x y A A+i k drop nextc 0 fi ; cr ." stack: " .s cr drop ; x y A A+i+1 else ; x y A A+i k ; now handle normal keys and characters dup 13 = if ; x y A A+i k 2drop ; here copy h1-h2 buff->h1 ; x y A h1 count h2 smove ; x y A dup count h1 smove ; x y A dup ; because A=A showbuffer and ctype should not ; display any green cursor. ; x y A A showbuffer ; reshow the cursor 7 6 cursor cr exit fi ; x y A A+i k ; backspace key dup 8 = if ; x y A A+i k ; delchar handles all cases drop delchar ; x y A A+i else ; No emit! because "showbuffer" does that. ; x y A A+i k insert ; x y A A+i+1 fi fi ; if extended or normal char ; x y A A+i again ; ; this version of accept is probably the most useful, so ; we will use it (because it has command history and editing ' accept.hist is accept : rev ( A n -- / type string in reverse *) swap over + 1- ; n A+n-1 swap 0 do ; A+n-1 c@- emit loop drop ; ; slightly easier to use than insert : c+s ( A c -- / insert char c to at start of A *) >r dup 1+ r> insert drop drop ; ; could use a do/loop here, or use a temporary string ;: U. ( n -- / print t-o-s as unsigned number *) ; 0 >r ; begin ; n' ; base c@ ; n b r: count ; u/mod r> 1+ >r ; r r ... quot /r r is a list of remainders ; dup 0= ; until ; drop r> 0 ; do ; digits + c@ emit ; loop drop ; times 19*1024-($-block1) db 0 ; try to create indexes ; ./ $-udot.so udot.so: : u. ;( n -- / print t-o-s as unsigned number in current base *) ; set pad="" 0 pad c! ; n begin ; n' base c@ u/mod ; r n'' swap digits + ; n'' D+r c@ pad swap c+s dup 0= until drop pad count type ; : head. ( xt -- / display word header in debug form *) dup 1- rcount ; xt A n / A= start of name drop 1- 1- ; print address ; xt A-2 cr dup u. ; xt A ; print link back address ." :[" @ dup u. ." ] -> " ; xt A 1- rcount type 1- cr ; xt-1 rcount >r dup u. ; a-n r: n ." : " r> dup >r ; a-n n r: n ; print word name in quotes ; use .xt here? /c/ " emit type /c/ " emit space r> ;*** print word length|control in quotes ;!! need to handle immediate words which have msb set u. cr ; : xytype ( A n x y -- / print string at [x,y] then reset cursor *) getxy 2swap atxy ; A n x y 2swap type atxy ; : asc ( -- / show asci codes *) 255 0 do ii dup 32 mod not if cr 15 fg ii u. space fi dup 14 mod 1+ fg emit loop ; : tri ( n -- / a triangle of color blocks *) 2 do ii glow cr loop ; ; list colours : color ( -- / show foreground and background colours *) 16 0 do space ii dup fg u. loop cr 16 0 do space ii dup bg u. loop 0 bg ; ; return true if a=A and b=B, or call d= (double equals) : 2= ( a b A B -- t/f ) swap >r = ; a flag(-1:true,0:false) r: A not if r> drop drop 0 exit fi r> = ; ; another version of 2= using logic, 7 ops versus 13 above : d= ( a b A B -- -1:true, 0:false ) swap >r = ; a flag(-1:true,0:false) r: A swap r> ; t/f a A = ; t/f t/f and ; times 20*1024-($-block1) db 0 ; count colons : and semi colons, to show source code slightly ; better. We use : and ; to indent definitions. var ncolon var nsemi ; a space margin var margin ; This do/loop may exceed +/-128 byte boundary. : codepage ( A n -- / format source code from A, length n *) ; initialise counters (newlines, : and ; ) 0 nn ! 3 margin ! ; if string length = 0 do nothing dup if0 2drop exit fi 0 do ; A c@+ ; A'+1 n ; ignore \r = asci 13. Below we use the trick of putting ; a dummy 0 on the stack to get an if/elseif/elseif/fi effect dup 13 = if drop 0 fi dup 10 = if drop 0 cr nn ++ 20 mod 0= if 10 fg ." >" 7 fg key /c/ q = if unloop exit fi cr ; add margin here margin spaces fi fi ; colon, add margin ; margin += 2 ; A'+1 n ; dup /c/ : = if margin 2 n++ drop fi ; dup /c/ ; = if margin -2 n++ drop fi dup if emit else drop fi loop drop ; ; list word names and execution token addresses : listxt ( -- ) last @ 0 nn ! 0 ll ! begin nn ++ 5 mod 0 = if ll ++ 20 mod 0= if ." ..." key drop fi cr fi dup 2 fg u. [char] : emit dup 6 fg .xt space xt+ dup 0 = until drop ; ; Display asci codes of keys pressed. See ekeycode for the ekey ; version : keycode begin key dup u. space dup emit cr [char] q = until ; : ekeycode ( -- / display keycodes for key-presses [ekey] *) begin ekey 2dup swap u. space u. drop cr [char] q = until ; times 21*1024-($-block1) db 0 ; direction is 1=east, 2=south, 3=west, 4= north ;( drawing with pixel lines, using length, compass direction ) ; draw a line starting a pixel position xy of length n ; ( x y n -- ) ; : line 1 do 2dup pix 1+ swap 1+ swap loop ; : line ( x y dx dy n -- x+dx*n y+dy*n dx dy / draw n pixels from [x,y] in dir dx/dy *) 0 do >r >r 2dup plot ; x y r: stepy stepx swap r> dup >r + ; y x+step r: stepy stepx swap r> r> ; x+step y stepx stepy swap >r ; x+step y stepy r: stepx dup >r + ; x+step y+step r: stepx stepx r> r> swap ; x+step y+step dx dy loop ; ; this should be a matrix multiplication : rot45 ( dx dy - dx' dy' / rotate step params by 45 degrees *) 2dup 1 0 2= if 1 1 2swap 2drop exit fi 2dup 1 1 2= if 0 1 2swap 2drop exit fi 2dup 0 1 2= if -1 1 2swap 2drop exit fi 2dup -1 1 2= if -1 0 2swap 2drop exit fi 2dup -1 0 2= if -1 -1 2swap 2drop exit fi 2dup -1 -1 2= if 0 -1 2swap 2drop exit fi 2dup 0 -1 2= if 1 -1 2swap 2drop exit fi 2dup 1 -1 2= if 1 0 2swap 2drop exit fi ; : rot90 ( dx dy - dx' dy' / rotate step params by 90 degrees *) rot45 rot45 ; : square ( x y lx ly -- / draw square at x y ) todo! ; : square ( x y -- / draw square at x y ) 1 0 ( start direction ) ; x y 1 0 4 0 do 20 line rot90 loop 2drop 2drop ; : octo ( x y -- / draw an octagon at x y *) 1 0 ; x y 1 0 8 0 do 20 line rot45 loop 2drop 2drop ; times 22*1024-($-block1) db 0 ; need to debug : fsquare ( x y n -- / draw filled square at x y with side length n *) >r 2dup 1 0 ; x y x y 1 0 r: n r> 0 do ; x y x y 1 0 iimax ; x y' x y' 1 0 iimax line 4drop ; x y' 1+ 2dup ; x y'+1 x y'+1 1 0 ; x y'+1 x y'+1 1 0 loop 2drop 4drop ; : grid ( -- / make a pattern *) cls 20 20 20 8 0 do ; x y' 20 3dup ii fg fsquare ; x y' 20 >r 30 + r> loop ; ; this is a very primitive recursive descent parser : palindrome ( A n -- flag / checks if a string is a palindrome) ; if stringlength <= 1 just call it a palindrome dup 0 = if drop drop 1 exit fi dup 1 = if drop drop 1 exit fi ; check first and last letters then recurse ; A n >r c@+ ./ A+1 c r: n r> swap >r ./ A+1 n r: c 2 - 2dup + ./ A+1 n-2 A+n-1 r: c c@ r> ./ A+1 n-2 b c = not if drop drop 0 exit fi ; for debugging ." recurse.. " palindrome ./ do recursion! nop ; : pal ." check: " pad accept pad count palindrome cr .s if ." palindrome!! " else ." nope " fi ; : showpal ." check: " ;pad 40 accept pad count pad accept pad count ; A n cr begin 2dup ; A n A n palindrome if 2dup type space fi swap 1+ swap 1- ./ A+1 n-1 dup 0 = until ; times 23*1024-($-block1) db 0 : wc ( xt -- n count words, not opcodes from word at xt ) ; assume <5000 words 5000 0 do ; assume all ops at top of dict, bad assumption! dup xt>op if drop ii unloop exit fi xt+ loop drop ; : allwords last @ wc ; ; count words defined in bytecode : bytewords last 4 - wc ; ; how many bytes do the opcodes occupy. : opspace ['] nop ['] exec - ; ; how much space do the bytecodes occupy. : bytespace ['] last ['] nop - ; : totalspace last @ ; : splash ( -- / produces a colourful splash screen *) 31 spaces 8 glow cr 30 spaces 10 glow cr 29 spaces 12 glow cr 28 spaces 14 glow cr 28 spaces 14 glow cr 29 spaces 12 glow cr 30 spaces 10 glow cr 31 spaces 8 glow cr cr 7 fg 23 spaces ." Teatree, A 'Forthish' System " cr cr 13 fg 20 spaces 6 fg ." Machine: " 13 fg mname cr 20 spaces 6 fg ." Opcodes: " 13 fg opspace u. ." bytes" ; ' nop literal ' exec literal - u. ." bytes" 10 fg ." ( " [op'] nop u. ." opcodes )" 13 fg cr 20 spaces 6 fg ." Byte codes: " 13 fg bytespace u. ." bytes" ; ' last literal ' nop literal - u. ." bytes" 10 fg ." ( " bytewords u. ." bytecode words ) " 13 fg cr 20 spaces 6 fg ." Total Size: " 13 fg last @ u. ." bytes" 10 fg ." ( " allwords u. ." total words ) " 13 fg cr ; ./ splash times 24*1024-($-block1) db 0 ; the simplest dump, no asci chars : dump.basic ( A n -- / display n bytes of memory *) ; print mem address swap dup u. ." : " swap 0 do c@+ u. space loop drop ; times 25*1024-($-block1) db 0 : 2over ;( a b c d -- a b c d a b /copy second double to top *) >r >r 2dup r> r> 2swap ; ;A naive line drawing algorithm ;dx = x2 - x1 ;dy = y2 - y1 ;for x from x1 to x2 { ; y = y1 + dy * (x - x1) / dx ; plot(x, y) ;} ; ; ; gradient variables. var dx var dy ; Bresenhams algorithm would be better, or Xaolin Wus but ; for the time being, lets just use "naive" defer lineto : lineto.naive ( a b c d -- / draw line from [a,b] to [c,d] *) 4dup swap >r swap - dy ! r> ; a b c d a c swap - dx ! drop drop ; a b ; if line vertical do it separately dx @ 0= if ; a b dup dy @ + ; a b b+dy dy @ 0 > if swap fi do dup ii plot loop ;." 0 dx!! " drop exit fi over dup dx @ + ; a b a a+dx ; if dx<0 then adjust the order of the loop parameters dx @ 0 > if swap fi do ; a b 2dup swap ii swap - ; a b b ii-a dy @ dx @ */ + ; a b b+dy(x-a)/dx ii swap plot ; a b loop drop drop ; ' lineto.naive is lineto ; stores zero byte at location : c!0 ( adr -- ) 0 swap c! ; : sspoints ( x y n -- a b c d e f g h / vertices of square side 2n, midpoint x y *) >r ; x y r: n 2dup swap r@ - swap r@ - ; x y a b r: n 2swap ; a b x y r: n 2dup swap r@ + swap r@ - 2swap ; a b c d x y r: n 2dup swap r@ + swap r@ + 2swap ; a b c d e f x y r: n 2dup swap r@ - swap r@ + 2swap ; a b c d e f g h x y r: n 2drop r> drop nop ; ; reverse line : rline ( a b c d -- a b / trace line from {c,d} to {a,b} *) 2swap 2dup >r >r lineto r> r> ; ; traces lines starting at point (x1,y1), ending at (xn,yn) ; This does not "close" the path : trace ( xn yn ... x1 y1 n -- xn xn / trace lines between n points on stack *) 1- 0 do rline loop ; times 26*1024-($-block1) db 0 ; traces lines starting at point (x1,y1), ending at (xn,yn) ; This closes the path : ctrace ( xn yn ... x1 y1 n -- / trace path between n points on stack *) dup 2swap 2dup >r >r ; ... n n x1 y1 r: x1 y1 2swap drop trace r> r> lineto ; ; traces lines starting at point (x1,y1), ending at (xn,yn) ; This does not "close" the path : pplot ( xn yn ... x1 y1 n -- / plot n points from stack *) 0 do plot loop ; : rswap ( r: a b -- r: b a / swap top 2 items on return stack *) r> r> r> swap >r >r >r ; : rvertex ( x y w h -- a b c d e f g h / leave vertices of rectangle, midpoint [x,y], width=w, heigth=h *) >r >r ; x y r: h w 2dup swap r@ ; x y y x w - swap rswap r@ - rswap ; x y a b r: h w 2swap ; a b x y r: h w 2dup swap r@ ; a b x y y x w r: h w + swap rswap r@ - rswap 2swap ; a b c d x y r: h w 2dup swap r@ + swap rswap r@ + rswap 2swap ; a b c d e f x y r: h w 2dup swap r@ - swap rswap r@ + rswap 2swap ; a b c d e f g h x y r: h w 2drop r> r> 2drop ; times 27*1024-($-block1) db 0 ; increments value stored at address a ; or call this ++ : !1+ ( a -- ) dup @ 1+ swap ! ; times 28*1024-($-block1) db 0 ( Double numbers, ie numbers on stack in form [a b] where b is high order item, 16bits, and also highest on stack ) ; some ron geere double number defs : 2rot ( a b c d e f -- b c e f a b /do rotate with doubles *) >r >r 2swap r> r> 2swap ; ; 4 pick 4 pick ( but we dont do pick ) : 2over ( a b c d -- a b c d a b /copy second double to top *) >r >r 2dup r> r> 2swap ; : 2@ ( A -- d / fetch double number from address A *) dup 2 + @ swap @ ; : 2! ( d A -- / store double number at address A *) dup >r ! r> 2 + ! ; : 2con ( define 32 bit double constant *) ( looks a bit dodgy ) ; ; con , does> 2@ ; imm ; this is called dminus in older forths. : dnegate ( d -- -d / negate double number d *) todo! ; times 29*1024-($-block1) db 0 : 0< ( n -- f / leave true if n is negative *) todo! ; : d- ( d1 d2 -- d3 / do d1-d2 double number subtraction *) dnegate d+ ; : d0= ( d -- f / leave true flag if double number is zero *) or = ; : d0< ( d -- f / leave true if double number negative *) swap drop 0< ; : d= ( d1 d2 -- f / leave true flag if both equal *) d- d0= ; ; '79 standard double compare. : d< ( d1 d2 -- f /leave true flag if d1 ( d1 d2 -- f /leave true flag if d1>d2, signed, else leave false *) 2swap d< ; ; : dmin ( d1 d2 -- d3 / leave minimum of 2 double numbers *) ; 2over 2over d< 0= if 2swap fi 2drop ; ; : dmax ( d1 d2 -- d3 / leave maximum of 2 double numbers *) ; 2over 2over d< if 2swap fi 2drop ; times 30*1024-($-block1) db 0 ; test prefix with a loop. But begin/again compiles to relative ; jump opcodes which have a limit of +/-128 bytes (instructions). ; If you put big messages here the loop fails. : t:prefix ." testing 'prefix': double enter to exit." cr begin ." Text:" pad accept ." Prefix:" buff accept pad count buff count ;." stack: " .s cr dup not if exit fi prefix ;." stack: " .s cr if ." True!" else ." Not a prefix" fi cr again ; ; a loop to test search. : ..search ." testing 'search': enter to exit." cr begin ." Text:" pad accept ." Search:" buff accept pad count buff count dup 0 = if exit fi ; A n P m search ; A n f ." stack: " .s cr if ." Found in 'pad':[" pad 1+ u. ." ]" ." at " drop u. cr else ." Not found" drop drop fi cr again ; times 31*1024-($-block1) db 0 ; Testing >number by accepting input and ; displaying the number : try.>number begin cr term accept term count dup 0 = if exit fi >number space . space dup u. space . cr again ; times 32*1024-($-block1) db 0 times 33*1024-($-block1) db 0 ; parse, compile and execute words. This is the interpreter. ; called 'quit' in ansi forth. Hopefully "thru" has defined ." etc ; above : shell cr ." FORTH shell is go!" cr ; primitive message 'F>' 70 emit 62 emit begin here>anon [op'] exit c, here>anon term dup accept count in0 in, anon pcall ok again ; 20 33 thru 34 55 thru shell times 34*1024-($-block1) db 0 ; : ascline begin 196 emit loop ; 179 side. A 10x10 box is not square... : abox ( x y lx ly -- / draw asci box at [x,y] width lx, length ly *) 4dup ; x y lx ly x y lx ly 2swap atxy ; x y lx ly lx ly ; top-left corner 218 emit drop 0 do ; x y lx ly 196 emit loop ; top-right corner 191 emit >r >r 1+ 2dup ; x y+1 x y+1 r: lx ly atxy r> r> ; x y+1 lx ly dup 0 do ; x y' lx ly 179 emit 4dup drop swap >r + 1+ r> ; x y' lx ly x+lx+1 y' atxy ; x y' lx ly 179 emit ; x y' lx ly >r >r 1+ 2dup ; x y'+1 x y'+1 r: lx ly atxy r> r> ; x y'+1 lx ly loop >r >r atxy r> r> ; lx ly ; bottom left corner 192 emit swap 0 do 196 emit loop ; bottom right corner 217 emit ; ; need to juggle the return pointer for function "2>r" : 2>r ( a b -- r: -- a b / put 2 items on return stack *) r> swap >r swap >r >r ; : 4>r ( a b c d -- r: -- a b c d *) r> swap >r swap >r swap >r swap >r >r ; : vocab ( -- / make a new wordlist ... *) create does> ." see block 48 " ; imm : ax+by ( a b x y -- a*x+b*y / row column matrix multiplication *) swap >r * ( a b*y r: x ) swap r> * ( b*y a*x ) + ; ( a*x+b*y ) ; This word does the matrix multiplication (useful for point rotations) ; | a b | * | x | ; | c d | | y | : 2x2Matrix* ( x y a b c d -- x' y' / left * 2x2 matrix a b c d *) 4>r 2dup r> r> ; x y x y a b r: c d ax+by ; x y ax+by r: c d swap >r swap r> ; ax+by x y r: c d r> r> ax+by ; ; ax+by cx+dy ; uses rotation matrix to rotate point by left multiplication ; Matrix = | 0 1 | ; | -1 0 | : xyrot90 ( x y -- x' y' / rotate [x,y] 90 degrees about 0 *) 0 1 -1 0 2x2Matrix* ; times 35*1024-($-block1) db 0 ; an xyset is a set of integer pairs [x,y] with a length ; points: (0,0) (0,1) (1,1) ; : xyset: ( -- / create a test xyset *) create 4 , 0 , 0 , 1 , 0 , 1 , 1 , 2 , 0 , does> ; imm ; remember the count or length of xyset is 16bit not 8bit char. : .xyset ( A -- / show values of xyset *) @+ dup . /c/ : emit space ; A+1 n 0 do ; A+1 /c/ [ emit @+ . /c/ , emit @+ . /c/ ] emit ii 8 mod if0 cr 4 spaces fi loop drop ; ; length of xyset is 16bit not 8bit : asciglyph ( c A -- / display xyset A as asci glyph with char c *) ; get current cursor pos getxy >r >r @+ 0 do ; c A' @+ >r @+ r> ; c A'+2 y x swap atxy over ; c A'+2 c emit ( asci block char ) loop drop drop ; restore cursor pos r> r> atxy ; ; show an xyset as a pixel glyph. I think "pix" is called ; "plot" in many forths. : xyglyph ( A -- / display xyset A as monochrome glyph *) ; get the xyset length (2 bytes) and loop @+ 0 do ; A' @+ >r @+ r> ; A'+2 y x swap plot ; A'+2 loop drop ; xyset: tt : txty ( dx dy A -- / offset xyset at A by dx dy *) @+ ; dx dy A+2 n 0 do ; dx dy A' >r 2dup r> ; dx dy dx dy A' >r swap r> ; dx dy dy dx A' dup @ ; dx dy dy dx A' x swap >r + ; store new x value in cell ; dx dy dy dx+x r: A' r> !+ ; dx dy dy A'+2 dup @ ; dx dy dy A'+2 y swap >r + ; store new y value in cell ; dx dy dy+y r: A'+2 r> !+ ; dx dy A'+4 loop drop 2drop ; : point ( x y -- / print [x,y] as a point *) /c/ [ emit swap . /c/ , emit . /c/ ] emit ; ; remember the count or length of xyset is 16bit not 8bit char. times 36*1024-($-block1) db 0 : animblock ( A -- / animate a block falling *) 12 0 do >r ; r: A ; show glyph ablock r@ asciglyph ; wait half a second 500 ms ; erase glyph 32 r@ asciglyph 0 1 r@ txty r> ; A loop ablock swap asciglyph ; vocab tetris ; Tetris blocks are "tetronimoes", 4 orthogonally joined squares. ; : Iblock: ( -- / tetris I block *) create 4 , 0 , 0 , 1 , 0 , 2 , 0 , 3 , 0 , does> ; imm : Sblock: ( -- / tetris S block *) create 4 , 0 , 0 , 1 , 0 , 1 , 1 , 2 , 1 , does> ; imm ; type text in rainbow colours : rainbow ( A n -- ) ; string length is 0 so do nothing dup 0 = if 2drop exit fi 0 do c@+ ; A'+1 n ; ignore \r = asci 13. Below we use the trick of putting ; a dummy 0 on the stack to get an if/elseif/elseif/fi effect dup 13 = if drop 0 fi dup 10 = if drop 0 cr fi dup if ii 8 mod 1+ fg emit else drop fi loop drop ; set colour back to normal 7 fg ; : rb" ( -- /rainbow coloured text *) post s" [call:] rainbow ; imm ; display next char at runtime : .c post [char] [op:] emit ; imm ; post s" ['] rainbow post call, ; imm ; post s" ' rainbow literal post call, ; imm ; This is not useful since we can just do ; x y atxy ." some text" ; : xy" post s" ; ' atxy literal post call, ; ' type literal post call, ; imm xyset: b1 Sblock: b2 ; translate the set ; this line is causing crash if not immediate [ 35 7 b1 txty ] [ 35 21 b2 txty ] : ftetris ( -- / a fake asci tetris *) ; put blocks in initial position ; but this requires a different word, not translate txty ; 35 7 b1 txty ; 35 21 b2 txty 3 vid ; hide the text cursor, its distracting 6 7 cursor 32 1 atxy 3 fg rb" Forth Tetris! " 25 2 atxy 7 fg ." Score: 31517 (High Score!) " 25 3 atxy 15 fg ." ---------------------------" 7 fg 24 0 30 22 abox 4 fg ablock b2 asciglyph ;6 fg ablock b1 asciglyph 6 fg b1 animblock ; show the text cursor again 7 0 cursor ; times 37*1024-($-block1) db 0 : ball: ( -- / create a xyset in shape of a ball *) create 16 , 1 , 0 , 2 , 0 , 3 , 0 , 0 , 1 , 1 , 1 , 2 , 1 , 3 , 1 , 4 , 1 , 0 , 2 , 1 , 2 , 2 , 2 , 3 , 2 , 4 , 2 , 1 , 3 , 2 , 3 , 3 , 3 , does> ; imm : setn ( A n -- x y / get the nth point [x,y] from set A [0 base] *) >r @+ r> ; A+2 m n ; if n => |S| then error 2dup <= if ; some error number drop 2drop 1234 1234 exit fi ; A+2 m n swap drop 4 * + ; A+2+4n @+ swap @+ swap ; x y A+4+n drop ; : rot90set ;( A -- / rotate xyset A by +90 degrees about 0,0 *) @+ ; A+2 n 0 do ; A' dup @+ swap @+ swap drop ; A' x y xyrot90 ; point ; A' x' y' >r swap !+ r> swap !+ ; A'+4 loop drop ; ; This is different to Dneg, double number negate. : 2neg ( x y -- -x -y / negate 2 stack items *) neg swap neg swap ; : xyset0 ( A n -- dx dy / translate set A, nth point to 0,0 *) ; This word leaves the displacement on the stack so that ; it can be used by txty after rot90set. over >r ; A n r: A setn 2neg 2dup r> ; -x -y -x -y A txty ; ; -x -y : xyset00 ( x y A -- dx dy / translate set A, so x,y--> 0,0 *) >r 2neg 2dup r> ; -x -y -x -y A txty ; ; -x -y ; Terminology: '' is a transformation of a set ; ' is a transformation of an xy point value ; ro' is a rotation of point [x,y] ; ro'' is a rotation of a set ; tr' - translation of point [x,y] ; tr'' - translation of an xyset/glyph ; We could call xysets psets (point sets) ; change this to ; : ro''pi/2.about ( A x y -- /rotates pset A about point [x,y] *) ; or even ; : ro''about ( A x y -- /rotates pset A about point [x,y] *) ; then do ; dup A n setn R'.about : rot90setn ( A n -- / rotate 90 degrees about Nth point in set ) ; A n swap dup >r swap ; translate A so that Nth point is at zero ; A n r: A xyset0 r@ ; dx dy A r: A rot90set 2neg r> ; -dx -dy A txty ; times 38*1024-($-block1) db 0 : arot ( A n -- / animate xyglyph A rotation n times *) 0 do ; A ablock over ; A c A asciglyph 500 ms ; A 32 over asciglyph ; A dup 1 rot90setn ; A loop ; : aarot ( A n -- / animate xyglyph A rotation n times *) 0 do ; A ablock over ; A c A asciglyph 500 ms ; A 32 over asciglyph ; A dup 1 rot90setn ; A dup 1 swap 1 swap txty ; A loop ; times 39*1024-($-block1) db 0 ; : table create does> swap 2* + @ ; imm ; the "code>here" is a cludge. Or use sync. ; Using : .. create doesnt seem to be working. ; : table create ; This table contains sine values * 10000 for degrees 0-90 [ create sinetable 0 , 175 , 349 , 523 , 698 , 872 , 1045 , 1219 , 1392 , 1564 , 1736 , 1908 , 2079 , 2250 , 2419 , 2588 , 2756 , 2924 , 3090 , 3256 , 3420 , 3584 , 3746 , 3907 , 4067 , 4226 , 4384 , 4540 , 4695 , 4848 , 5000 , 5150 , 5299 , 5446 , 5592 , 5736 , 5878 , 6018 , 6157 , 6293 , 6428 , 6561 , 6691 , 6820 , 6947 , 7071 , 7193 , 7314 , 7431 , 7547 , 7660 , 7771 , 7880 , 7986 , 8090 , 8192 , 8290 , 8387 , 8480 , 8572 , 8660 , 8746 , 8829 , 8910 , 8988 , 9063 , 9135 , 9205 , 9272 , 9336 , 9397 , 9455 , 9511 , 9563 , 9613 , 9659 , 9703 , 9744 , 9781 , 9816 , 9848 , 9877 , 9903 , 9925 , 9945 , 9962 , 9976 , 9986 , 9994 , 9998 , 10000 , code>here ] ; the "code>here" is a cludge. Or use sync. ; This is very old code. : tsin ( n -- a' / get a value from the sinetable *) sinetable swap 2* + @ ; times 40*1024-($-block1) db 0 : (sin) ( x -- x' /adjust sin for 90 < x < 180 *) dup 90 > if 180 swap - fi tsin ; : sin ( x -- sin[x]*10000 / calculate scaled sin[x] from table *) 360 mod dup 0 < if 360 + fi dup 180 > if 180 - (sin) negate else (sin) fi ; : cos ( n -- n') 360 /mod drop 90 + sin ; : vals ( show values ) do ii dup . sin ." sin(x):" . cr ; ii sin(ii) loop ; : wave ( n m -- /draw a sine wave from n degrees to m degrees *) do ii dup sin 80 / 170 + plot ; ii sin(ii) loop ; ; rotate point about 0,0 X degrees counter clockwise ; R = | cos(x) -sin(x) | ; | sin(x) cos(x) | times 41*1024-($-block1) db 0 ; this is useful for rotations using sin/cos rotation matrix ; since the trig values are scaled by 10000. It assumes a & b ; are scaled by 10K : ax+by/10k ( a b x y -- a*x+b*y/10k / matrix mult scaled by 10000 *) swap >r 10000 */ ( a b*y r: x ) swap r> 10000 */ ( b*y a*x ) + ; ( a*x+b*y ) ; Since trig functions in forth are usually scaled by 10000 ; we need to unscale them when calculating the rotation ; This word does scaled matrix multiplication (useful for point rotations) ; | a b | * | x | ; | c d | | y | : 2x2Matrix*/10k ( x y a b c d -- x' y' / left * 2x2 matrix a b c d *) 4>r 2dup r> r> ; x y x y a b r: c d ax+by/10k ; x y ax+by r: c d swap >r swap r> ; ax+by x y r: c d r> r> ax+by/10k ; ; ax+by cx+dy : rmatrix ( n -- c -s s c / make an n-degree rotation matrix * 10000 *) ; all trig values are * 10000 because basic forth has no ; floating point dup cos dup >r ; n cos r: cos swap sin dup neg swap r> ; ; cos -sin sin cos ; sin and cos are scaled by 10000 : xyrotn ( x y n -- x' y' / rotate [x,y] n degrees about 0 anti-clock *) rmatrix ; x y cos -sin sin cos 2x2Matrix*/10k ; : xyrotnabout ( x y a b n -- x' y' / rotate [x,y] n degrees about [a,b] anti-clockwise *) ; not not a set here, just x,y ; bug! >r xyset00 ; x' y' dx dy r: n r> swap >r swap >r ; x' y' n r: dy dx rmatrix ; x' y' cos -sin sin cos 2x2Matrix*/10k r> swap >r + ; x''+dx r: dy y'' r> r> + ; ; x''+dx y''+dy times 42*1024-($-block1) db 0 : rotset ( A n -- / rotate xyset A n degrees about 0,0 anti-clockwise *) swap @+ ; n A+2 m 0 do ; n A' swap >r dup ; A' A' r: n @+ swap @+ swap drop ; A' x y r: n r@ ; A' x y n r: n xyrotn ; A' x' y' r: n ;2dup point cr ;.s cr >r swap !+ r> swap !+ ; A'+4 r: n r> swap ; n A'+4 loop drop drop ; ball: bb [ 250 150 bb txty ] : swing ( n -- animate with n iterations *) ;bb 1 xyset0 ;250 150 bb txty 0 do 3 fg bb xyglyph 200 ms 0 fg bb xyglyph bb 3 rotset loop ; times 43*1024-($-block1) db 0 ; should be able to write turtle graphics now with ; trig functions and lineto. ; sin(t) = (y1-y0)/r ; y1 = r.sin(t) + y0 ; cos(t) = (x1-x0)/r ; y2 = r.cos(t) + x0 : polar ( x y t r -- x' y' / find co-ords distance r at angle t *) >r dup sin ; x y t sin(t)*10K r: r r@ 10000 */ ; x y t r*sin(t) r: r swap >r + ; x r.sin(t)+y r: r t swap r> ; r.sin(t)-y x t r: r cos r> 10000 */ ; r.sin(t)+y x r.cos(t) + swap ; ; r.cos(t)+x r.sin(t)+y : ray ( x y l -- / draw rays from {x,y} length l *) 0 nn ! begin ; x y l >r 2dup 2dup ; x y x y x y r: l nn ++ 20 * r@ polar ; x y x y x' y' r: l lineto r> ; x y l nn @ 20 * 360 > ; stop when > 360 degrees until drop drop drop ; : mm 100 0 do 100 ii + 100 ii + 30 ray 200 ms loop ; : histo ( A n -- / plot histogram from data at A length n *) 0 do loop ; [ create somedata 0 , 175 , 349 , 523 , code>here ] times 44*1024-($-block1) db 0 : arc ( a b r -- / draw 1 arc of a circle *) ; : ytri ( x h -- y / height of right triangle *) ; y = sqrt(h^2-x^2) dup * swap dup * - sqrt ; : arc ( a b r -- / draw 90 deg arc of radius r midpoint [a,b] *) ; x2+y2=r2, so y=sqrt(r2-x2) dup 1 do ; a b r 3dup ; a b r a b r ii over ; a b r a b r ii r ytri ; a b r a b r y ; now add midpoint to (x,y) swap drop + ; a b r a b+y swap ii + ; a b r b+y a+x swap ; a b r x' y' plot loop ; : circle ( a b r -- / draw circle of radius r midpoint [a,b] *) ; x2+y2=r2, so y=sqrt(r2-x2) dup 1 do ; a b r 3dup ; a b r a b r ii over ; a b r a b r ii r ytri ; a b r a b r y swap drop ii swap ; a b r a b x y rvertex 4 pplot loop 2drop drop ; : fcircle ( a b r -- / draw filled circle of radius r midpoint [a,b] *) ; x2+y2=r2, so y=sqrt(r2-x2) dup 1 do ; a b r 3dup ; a b r a b r ii over ; a b r a b r ii r ytri ; a b r a b r y swap drop ii swap ; a b r a b x y rvertex 4 ctrace loop 2drop drop ; times 45*1024-($-block1) db 0 ; x and y steps for pong var xx var yy var delay : pong ( -- / bounce a square around ) 1 xx ! 1 yy ! 20 delay ! cls 10 0 atxy rb" Almost pong!" cr ." q=quit, r=reverse, f=faster, s=slower" cr 200 200 110 sspoints 4 ctrace ; initial pong position 130 180 ;2000 0 do begin ; x y key? if key dup /c/ q = if exit fi dup /c/ f = if delay @ 3 - delay ! ; not appearing? ; 30 1 atxy ." delay=" delay @ . fi dup /c/ s = if delay @ 3 + delay ! fi /c/ r = if xx @ neg xx ! yy @ neg yy ! fi fi ; x y ; set initial colour of shape ; 6 fg 2dup square 6 fg 2dup 10 fcircle ; speed determined by millisecond delay delay @ ms ; delete the shape by setting colour to black ;0 fg 2dup square 0 fg 2dup 10 fcircle ; check y-bounds (vertical walls) ; x y dup 100 300 within ifnot yy @ neg yy ! fi ; or check each wall one by one ;dup 200 >= if yy @ neg yy ! fi ;dup 20 < if yy @ neg yy ! fi swap dup 100 300 within ifnot xx @ neg xx ! fi swap yy @ + swap xx @ + swap again ; times 46*1024-($-block1) db 0 : rect ( x y w h -- / draw rectangle with midpoint x y *) rvertex 4 ctrace ; : nrect ( x y w h n -- / draw rectangle, midpoint x y, n thick *) 0 do ; x y w h 4dup ii + swap ii + swap rect loop ; ; might be better to rewrite this with a begin/until loop ; adding the degree increment each time. This would allow us ; to set a start angle for the points (so we could also do ; circular animations. : ccpoints ( x y r n -- / get n points on circle radius r, mid [x,y] *) 0 do ; x y r >r 2dup r> ; x y x y r 360 iimax / ii * ; x y r x y r t swap >r r@ polar ; x y ... x' y' r: r 2swap r> loop 2drop drop ; times 47*1024-($-block1) db 0 ; standard forth : \ 10 parse drop drop ; imm : { ( -- / we cant do local variables... yet *) [char] } parse drop drop ; imm : rot ( a b c -- b c a ) >r swap r> swap ; : -rot ( a b c -- c a b ) rot rot ; ; Bumgarner sin function (job-82mar31) ; from Ron Geere: Forth: the next step ; not working, not leaving anything on the stack var xs 0 xs ! ( square of scaled angle ) : kn ( a b -- m / m=10000-ax*x/b ..common term in series *) xs @ swap / minus 10K */ 10K + ; : (sine) ( theta -- 10K*sin /-15708 + c@ ; imm : vector ( n -- / compile n 16bit cells off stack into buffer *) create 0 do , loop does> + @ ; imm ; create and initialise a list vector (see list: for comparison) ; from the stack. lvector has the format ; 16bit length, 16bit data cells (no capacity cell) : lvector ( n -- / create and init list vector {length,data} *) create dup , 0 do , loop does> ; imm ; create and initialise a capacity list vector (same as list: ) ; from the stack. llvector has the format ; 15bit capacity, 16bit length, 16bit data cells ; use the words li/addu etc to manipulate it : llvector ( c n -- / create and init list vector {cap,length,data} *) create \ 1st 2 bytes are capacity swap dup , \ 2nd 2 bytes are length swap dup , \ init n words from stack ; n 0 do , loop ; set remaining capacity bytes to zero ; bug need to do c-l then allot ; c allot0 does> ; imm ; Use capital case for wordlist names? eg Editor, Forth, Assembler ; some words to try to create namespaces/ wordlists : zerolink ( xt -- / reset back-link in word xt to zero *) nop ; ; Actually we are not going to have a list of wordlists. ; So dont need this. ; There is always at least the "forth" (core?) namespace, which ; points to the core dictionary ; ; make NS point to the Forth NS. But when we add new words ; this becomes out of date, so create should update this, ; or we should just use Forth instead of "last/latest" ; Or make "last" do Forth @ ; makes the last defined word have a zero backwards link ; which means that effectively it is the first word in this ; or a new wordlist ; zerolink ; s/o is the search order buffer. Consists of a length ; (initially 1 ?) and a list of pointers to wordlists 16 buffer: s/o ; search order has nothing in it. s/o 0 swap ! ; an nset is a set of 16 bit items with length n (no capacity cell) : nset/dump ( A -- / display contents of nset at A *) dup @ dup ." [" u. ." items ] " dup 0= if drop exit fi ; A n swap 2 + swap ; A+2 n 0 do ; A' @+ . space loop ; times 49*1024-($-block1) db 0 ; Vocabs are unusual because they are manipulated through ; the s/o search order buffer. There is no direct way to ; access their data field (which contains a pointer to the ; last word defined in the wordlist). ; ; vocabulary in ans forth. Invoking the name of a wordlist ; set "current"= (replacing top item in search-order ; but we also need to get access to the pointer field of ; the vocab (maybe with "nfind" etc ?). ; The data field in the vocab is a pointer to the last word ; in this wordlist. "vocabulary" does not seem to exist in modern ; forth standards : vocab ( -- / create a new wordlist *) create 0 , does> ; replace last item in s/o (search order) buffer with ; top of stack (pointer to data field of new wordlist) ; If s/o is empty, add wordlist to s/o ; A s/o @ 0= if ; add to empty search order ; A 1 s/o !+ ! else ; A s/o dup @ 2* + ; A S' ! fi ; imm ; 5 is a magic number, the data field is 6bytes after ; the (reverse) count field of the wordlist name. : .vname ( A -- / print vocab name from pointer to data field A *) 5 - rcount type ; : memdup> ( A -- / copy cell [2bytes] at A to A+2 *) @+ swap ! ; : also ( -- / duplicate top item on search-order stack *) s/o @ 0= if ; if nothing in s/o then do nothing drop exit else s/o dup @ 2* + ; A+l*2 memdup> s/o ++ drop fi ; ; just testing wordlist creation and management. vocab Fth vocab Edit vocab Asm Fth also Edit also Asm : only ( -- / reduce s/o to minimum wordlists {forth} *) 0 s/o ! Fth ; ; look up s/o and gett last item ; in s/o buffer (s/o is like a stack, and last item is ; top of stack) : context ( -- A / A is p* to p* to first wordlist in search order *) s/o dup @ 2* + ; ; ( pointer to data-field of wordlist for new definitions *) ; This will probably be defined in bytecode, so that "create" ; can use it to compile the dictionary. var current ; called definitions in Ans forth ; Actually context @ is a pointer to the data-field of a ; wordlist, not to its execution token : defs ( -- set "current":="context" *) context @ current ! ; Fth defs ; This word is more useful for testing. In practice the last ; word in a wordlist is determined by create etc. ; eg: Forth ' dup setlast : setlast ( xt -- / set last word in "context" wordlist *) context ; xt A @ ! ; times 50*1024-($-block1) db 0 : order ( -- display all wordlists in search order & current *) s/o dup @ 2* + ; get name of wordlist ; L ." Search Order: " s/o @ 0 do ; A' ; @- .vname space dup @ dup ; A' B B ; print vocab name and last word in that list .vname /c/ ( emit @ .xt /c/ ) emit space 2 - loop drop cr ." current (def): " current @ .vname ; ; called previous in ans forth : prev ( -- / drop one wordlist from search order *) s/o @ <> if s/o -- drop fi ; ; list words in "context" : words ( -- / list all words in first wordlist of search order *) nop ; ; dont need zerolink, when a new vocab is created it ; as a zero link anyway. times 51*1024-($-block1) db 0 : xt>name ( xt -- A n / return name from word xt *) 1- rcount ; ; gforth word str= : str= ( cA u cB v -- F / leave true if strings are = *) rot over ; A B v u v ; if lengths not equal, false <> if 3drop 0 exit fi ; A B v ncompare ; ; gforth is... ; : find ( cA – xt +-1 | cA 0 ) ; "last" is "latest" in many forths ; This is slightly different from Ans forth find ( A -- xt) ; hence the slightly different name. ; testing wfind (search wordlists) Fth ' timer setlast ; instead of only searching from "context" this should ; search all wordlists in the s/o search order buffer. : wfind ( A n -- xt|0 / find word matching name at A length n *) ; context is first wordlist in "s/o" search order list ; here we need to loop through each item in s/o starting ; at end of buffer (context pointer). And also check that ; last<>0 in vocab (if the wordlist is empty) context @ @ begin ; A n xt >r 2dup r@ ; A n A n xt r: xt xt>name ; A n A n B m r: xt str= ; A n F r: xt if 2drop r> exit fi r> xt+ dup 0= until 3drop 0 ; times 52*1024-($-block1) db 0 ; These always act on double precision numbers ( 2 items on stack ) : # ( ud – ud' / divide u by base, prefix remainder digit to pad as asci char *) nop ; : #s ( ud – ud' / convert all remaining digits using # *) nop ; : hold ( c -- / prefix char c to numeric string *) ; : sign ( n -- / if n<0 prefix '-' to numeric string *) ; : <# ( -- / clear the numeric output string. *) ; : #> ( xd – A u / discard xd and return numeric string *) ; ; just to test wfind : wf wparse wfind .s ; imm times 53*1024-($-block1) db 0 : abort" ( -- / clear the stacks etc *) post s" [call:] rainbow ; imm ( Ideas from pforth ) ; called 0sp in pforth : clear ( -- / remove all items from the data stack *) depth 0 do drop loop ; : comp? state @ if ( not compiling ) abort" ohoh" fi ; ( If echo is on then forth code will be echoed as it is compiling. ) var echo ; I like this idea of not having a fixed buffer for ; pad. Can use for obuff. This doesnt work in my ; current forth because I use an anonymous buffer ; to compile to. : PAD here 128 + ; times 54*1024-($-block1) db 0 ; This word should be able to handle opcodes as well ; as calls, but the opcode PCALL only does words. ; Ansi forth "execute", maybe called "perform" in older forths : ex ( ... xt -- / execute word at xt *) dup xt>op dup if swap drop ( op ) obuff ( opcode call compile buffer ) ( op A ) c!+ [op'] exit ( A'+1 EXIT ) swap c! obuff pcall else ( xt 0 ) drop pcall fi ; : perform ex ; : execute ex ; times 55*1024-($-block1) db 0 ; words from Ting/Muench eforth : hld ( hold pointer in building numeric string ) pad ; ; um+ can be used as a primitive for a number of words : negate ( n -- -n) not 1 + ; : dnegate ( d -- -d) not >r not 1 um+ r> + ; : d+ ( d e -- d+e ) >r swap >r um+ r> + ; ; defining opcodes as words. This may be useful for creating ; systems with very few opcodes (and therefore, in theory) ; easier to port to new architectures. But we need a mechanism ; to actually register these words as opcodes in the opcode ; table, and to execute them. : ?dup ( n -- n n | 0 ) dup if dup fi ; ; : not -1 xor ; ; : + ( a b -- a+b ) um+ drop ; ; : - negate + ; ; : = ( n n -- F ) xor if 0 exit fi -1 ; ; : here dp @ ; ; This pad is similar to pforths definition ; : pad here 80 + ; : @execute ( A -- ) @ ?dup if execute fi ; %endif ; }code ; the %if 0 trick below allows including forth source code without ; hundreds of "db" lines. But this source needs to be preprocessed ; to insert the dbs before every line ; below contains lots of standardish forth words. ; This is just a guide to naming conventions and to avoid name clashes ; with standard words. This is also an attempt to create a "literate" ; style of forth coding, where the explanation and documentation of ; the forth word is clearly visible next to the words definition. %if 0 FORTH CHESS NOTES A sketch of some chessy words. Before implementing this, we need working vocabularies, also probably a block editor . See also the chess.txt file in the folder "osdev" for more chess code. board: 0-11, 12-23, 24-35 ... .square ( n -- ) print a square number (12*8 board: 0-97) in chess algebraic eg a3, b2 h1. .move ( from to -- ) print a chess move where from and to are squares on a 12*8 board. .game ( C -- ) display the state of the game object, including the board and pieces, the moveVector (Pvector), the squareVector (current move piece or square). move>> ( C -- from to ) the next legal move for game "C" The move is returned on the stack. The game structure C is not altered (move+ does that). This will return 0 0 if there are no more legal moves on the board for the current player move+ ( C from to -- ) update the board position of C with the given move. The Pvector in the C game object will be advanced, or the Svector (current piece/square) will be advanced with piece+. piece>> ( C -- square ) the next piece on the board for the player colour This will return 0 if no more pieces to check for the current player The C game object is not altered (piece+ does that) piece+ ( C -- square ) update the current piece of position C with the given move piece vectors: : vknight [ n c, 1 c, 2 c, ... 0 c, ] ; : vpawn [ ... ] ; The structure of the piece vector is the displacement value, (eg +12 for a white pawn), then the multiplier (eg 4 for a rook moving 4 squares), and then the multiplier limit (one more than the maximum value). When C move+ executes it updates the value of Pvector in the game object, either by increasing the multiplier by one, or by advancing the Pvector pointer to the next piece direction (Pvector + 3), or by calling C piece+ (if the current piece has no more legal moves... ie the termination 0 of the vector has been reached). piece vector table: : vtable 2 c, ' vwpawn c, 6 c, ' vknight c, etc ... ]; The piece vector table is used to reestablish the Pvector after C piece+ is called (point to the correct piece vector for the current move square). IDEAS FOR WORDS A word to tell if a character is a digit. : ?digit ( c -- flag ) [char] 0 [char] 9 1+ within words ( -- ) list all the words in the dictionary in search order quit this is the standard forth repl loop. ie read evaluate print loop. It is a strange name and I will call it "shell" instead. The quit loop allows the user to type and execute commands. and compile new words. d. ( d -- ) display the top 2 stack items as a signed double precision integer. d+ d2* d2/ double precision integer operations The high cell is the high order byte of the double number. m* ( n1 n2 -- d ) multiple n1 by n2 and leave double precision result d on stack var creates a new variable : var ( -- ) create we could define colon : with an immediate create. eg [create] : ... source ; : bl 32 ; put a space character on the stack (20H) ; ideas for words of3 ( a b c n -- n/0 ) if n == a or b or c return that value, otherwise return 0. : of3 dup >r = if drop drop r> exit fi r> dup >r = if drop r> exit fi r> dup >r = if r> else r> drop 0 fi ; better to use r@ here, more readable than r> dup >r of2 ( a b n -- n/0 ) if n == a or b return that value, otherwise return 0. : of2 dup >r = if drop r> exit fi r> dup >r = if r> else r> drop 0 fi flags ( -- flag-reg ) put the overflow/carry etc flags register on the stack. I always wonder why standard forths dont have this. How do you know when an overflow or carry occurs? How can you call forth a virtual machine if it does not have this? ; input stream >in ( -- a-addr ) return address containing offset in characters from the start of the current input source to the start of the current parse point. In the current forth, ">in" works differently. Need to think about this design. evaluate ( ... addr u -- ... ) set input source to addr with length u. set >in to zero etc The current forth calls this in0 or setin and works differently A similar word might be "source" or "load". parse ( char -- addr n ) parse text at starting at current parse point ( >in ) using char as the delimiter. Also copy to temp location. But current forth is different. Word is not copied. Also we need a wparse which parses to any whitespace (eg newline is a word delimiter too!). Maybe parse should just update the >in variable as well which should make things simple. ( a comment) brackets for multiline comments a definition of "(" but I may parse bracket comments until a dot . so as to be able to write more "literate" forth. : ( char ) parse/word ... word ( char - c-adr n ) the same as parse but skip all leading occurences of char. My implementation is call WPARSE and works slightly differently (only parses on whitespace) ;*** stack over ( a b -- a b a ) nip ( a b -- b ) rot ( a b c -- b c a ) tuck ( a b -- b a b ) ; characters bl ( -- 20H ) return asci char 32 which is a space. char n ( -- char ) put the asci value of the first character in the next word in the input stream on the stack. In the current forth, this will be an immediate word. Not working in : COLON defs, needs to push a literal In many forths [char] must be used in : definitions. This is because the current forth compiles even words entered interactively. ;*** Strings ; we can implement string functions by compiling right in the ; midst of the current word and compile a JUMP over the string ; if necessary ," compile a string at current position in data-space (at "here") s" compile a string and put its address and length on stack at runtime ." compile a string and print it out at runtime. search find one string in another ; text display space display one space on terminal spaces ( n -- ) display n spaces on terminal cr emit one newline/ carriage return to terminal ; time and date ms ( u -- ) wait for u milliseconds time&date ( -- secs mins hours days months years ) return a structure representing time and date ; double numbers, which are 2 stack item numbers ; high (top) stack position is high order value ; eg D == a b where "b" is high value and a low d+ ( a b c d -- b:a + d:c ) d- d2* d2/ d>s convert double number ; arithmetic : */ ( a b c -- a*b/c). multiply 3TOS by NOS, keeping precision (double?) and then divide by TOS. ; mathematics : min ( a b -- min ) returns the lowest number of "a" and "b" (but signs ?). : max ( a b -- max ) returns the maximum number of "a" and "b". : mod ( m n -- p ) the modulus of m with n. Euclids greatest common divisor (after R.V.Noble) This is amazingly succinct. And recursion works! : gcd ( a b -- gcd) ?dup if tuck mod gcd fi ; ; sum of 1..n arithmetic series ( n -- ); eg 100 asum = 1+2+3...+100 : sum 0 do ii 0 = if 0 fi ii + loop ." sum = " u. ; ; or eg sum = n*(n-1)/2 : sum dup 1- u* 2 / ; The following gives pi to 2 decimal places, scaled by 100 : pi 35500 113 / ; Better, if double arithmetic is available : pi 103993. 33102. / ; pi.approx ( ) pi=4/1-4/3+4/5-4/7+4/9-4/11 an infinite series, but this may take 500000 iterations to get to 4 decimal places In forth we can scale by 10000 to get 5 decimal places See also the inverse tangent function. : 40K 40000 ; : pi.approx ( -- pi-ish) 0 1 begin dup 40K swap / swap >r + r> 2 + dup 40K swap / swap >r + r> 2 + dup 64001 = until drop ; The code above does 64K iterations quickly but only gets to 2 decimal places accurately ie 31407 (3.1407). Also we scale the result by 10K because forth doesnt have floating arithmetic. We really need double arithmetic (32 bit, 2 cells) to get a better approximation ; ans 94 forth word : within ( n a b ) return true != 0 if a <= n < b, otherwise return false==0 notice r min max r> = ;" I have used the reverse names compared to those used by Ron Geere, since "within" is now a fairly standard word with its parameter order. squareroot ( n -- n^0.5 ) use (n/x + x)/2 for successive approximations ; This is very cool and gets a good approximation within about ; 6 or so iterations. : approx ( n x -- n x' ) gets the next approximation to the square root, from ron geere. over over / + 2 / ; : sqrt ( a -- b ) return b, the approximate square root of a (maximum 32767 if the / division operator is signed, or else 64K if not), this just does the iterations of the "approx" word. 60 5 0 do approx loop swap drop ; ;*** execution execute ( ... xt -- ... ) execute word specified at address xt. Called 'pcall' in this forth recurse ( -- ) append execution behaviour to current definition to allow for recursive functions. In this implementation words can just call themselves eg: : gcd ( a b -- gcd) ?dup if tuck mod gcd fi ; ; dictionary and defining words state ( -- addr ) return address of state variable (either compile or run...) This is a way to implement the [ ] words which in this version of forth will make all words immediate when between "[" and "]". [ ( -- ) Enter "immediate" state. All words are executed, not compiled In standard forths, these are called "compile" and "interpret" states. ] leave "immediate" state. All words are compiled, unless they are marked immediate in their control bits (1st bit of the name count). literal ( n -- ) compile value n so that value n is put on the data stack at run-time. In this forth there is also and opcode LITERAL which could be confusing although they do almost the same thing. compile, ( xt -- ) append execution behaviour of xt to current definition. But because I am using opcodes as well, I have modified this word. Was going to call "item," because my version also compiles literal numbers. "opcode," is just "c," : unused ( -- u ) return number of bytes of memory remaining for new dictionary entries. : free first here - . ." bytes cr ; an older name for "unused". where first is the address of the first disk buffer. >body ( xt -- addr ) given execution token for a word, return the start of the parameter field (which is just after code). But current forth doesnt maintain a link to parameter field normally. : ' ( -- xt ) search dictionary for name and return execution token example: A table of function pointers [create] buttons ' start , ' slow , ' fast , ' finish : allot ( n -- ) allocate u bytes of data-space, beginning at the next available location. Normally used immediately after "create". here + here! ; create compile "name" in the dictionary and put address on stack at runtime (no data space is allocated). Because all words are first compiled in this forth we need an immediate version [create] to use this outside of a : definition. Or use [ create ] name ... This was called " really important word. Allows the creation of new defining words (eg "constant") that have a special behaviour. Needs to be used with create. Implentation is slightly tricky because no room in new word code field for a fcall to the does> code. So need to code a jump after the parameter field. Compiles a call to following words in defined words. * create a constant defining word : constant create 1 allot does> @ ; buffer: ( n -- ) create a dictionary entry for "name" associated with n bytes of data-space. create allot ; dump ( adr +n -- ) display the contents of a memory region of length n. print address on left and 8 values per line in hex values or current base. ;*** blocks and buffers list ( n -- ) display the contents of disk block "n" (1K of source code). blocks are good because no file system is required. buffer ( n -- addr ) return address where block n may be loaded. No read is done. A disk write is done if necessary. Buffer manages a list of buffers and blocks and finds a suitable place to put the requested disk block, but it doesnt actually read it into memory. block ( n -- addr ) return buffer address containing disk block n. Data is read if necessary. No write is done update ( -- ) mark the last disk block accessed as having changed data (needs to be written to disk). This could be stored in the last byte of the block itself load ( n -- ) load disk block (1024bytes) "n" and interpret the contents of the block as forth source code. flush ensure all updated buffers are written to disk and free all buffers. // create a dictionary entry for name associated with 1 cell // eg: variable data 6 data ! : variable ( -- ) create 1 allot ; immediate // create a new variable and assign a value to it. : value ( n -- ) create , ; immediate : to ( newval to name ) // a constant value : constant create , does> @ ; immediate %endif ; 0