From: Jonas Hvid Date: Sun, 8 Mar 2020 13:19:27 +0000 (+0100) Subject: Move some Forth words to separate 'bootstrap.asm' file X-Git-Url: https://git.rrq.au/?a=commitdiff_plain;h=a856c7d5b35de1b48bdd948186ec4a03f7c3685c;p=rrq%2Fjonasforth.git Move some Forth words to separate 'bootstrap.asm' file --- diff --git a/Makefile b/Makefile index 786399f..1bfaabe 100644 --- a/Makefile +++ b/Makefile @@ -2,7 +2,7 @@ run: main cat sys.f - | ./main -main: main.asm impl.asm +main: main.asm impl.asm bootstrap.asm fasm $< $@ .PHONY: clean diff --git a/bootstrap.asm b/bootstrap.asm new file mode 100644 index 0000000..1fc941a --- /dev/null +++ b/bootstrap.asm @@ -0,0 +1,97 @@ +;; vim: syntax=fasm + +;; We need some basic words to be available before we can implement the actual +;; interpreter. For this reason we need to write some words in assembly, even +;; though they depend only on other Forth words. Such words are defined in this +;; file. +;; +;; With these words, we can finally defined INTERPRET, and from there we'll load +;; everything else from an external file. +;; +;; This file is included from main.asm; see that file for more information. + +;; Define a Forth word that is implemented in Forth. (The body will be a list of +;; 'dq' statements.) +macro forth label, name, immediate { + header label, name, immediate + dq DOCOL +} + +forth COMMA, ',' + dq HERE, GET, PUT ; Set the memory at the address pointed to by HERE + dq HERE, GET, LIT, 8, PLUS ; Calculate new address for HERE to point to + dq HERE, PUT ; Update HERE to point to the new address + dq EXIT + +;; Mark the last added word as immediate. +forth IMMEDIATE, 'IMMEDIATE', 1 + dq LIT, 1 + dq LATEST, GET + dq LIT, 8, PLUS + dq PUT_BYTE + dq EXIT + +;; Given the address of a word, return 0 if the given word is not immediate. +forth IS_IMMEDIATE, 'IMMEDIATE?' + dq LIT, 8, PLUS + dq GET_BYTE + dq EXIT + +;; Enter immediate mode, immediately +forth INTO_IMMEDIATE, '[', 1 + dq LIT, 0, STATE, PUT_BYTE + dq EXIT + +;; Enter compilation mode +forth OUTOF_IMMEDIATE, ']' + dq LIT, 1, STATE, PUT_BYTE + dq EXIT + +;; The INTERPRET word reads and interprets user input. It's behavior depends on +;; the current STATE. It provides special handling for integers. +forth INTERPRET, 'INTERPRET' + ;; Read word + dq READ_WORD + dq PAIRDUP + ;; Stack is (word length word length). + dq FIND ; Try to find word + dq DUP_ + dq ZBRANCH, 8 * 22 ; Check if word is found + + ;; - Word is found - + + dq STATE, GET, ZBRANCH, 8 * 11 ; Check whether we are in compilation or immediate mode + + ;; (Word found, compilation mode) + dq DUP_, IS_IMMEDIATE, NOT_, ZBRANCH, 8 * 6 ; If the word is immediate, continue as we would in immediate mode + + ;; Otherwise, we want to compile this word + dq TCFA + dq COMMA + dq DROP, DROP + dq EXIT + + ;; (Word found, immediate mode) + ;; Execute word + dq TCFA + ;; Stack is (word length addr) + dq SWAP, DROP + dq SWAP, DROP + ;; Stack is (addr) + dq EXEC + dq EXIT + + ;; - No word is found, assume it is an integer literal - + ;; Stack is (word length addr) + dq DROP + dq PARSE_NUMBER + + dq STATE, GET, ZBRANCH, 8 * 5 ; Check whether we are in compilation or immediate mode + + ;; (Number, compilation mode) + dq LIT, LIT, COMMA + dq COMMA + dq EXIT + + ;; (Number, immediate mode) + dq EXIT diff --git a/example.f b/example.f index 2443f32..41993d7 100644 --- a/example.f +++ b/example.f @@ -1,3 +1,6 @@ +( vim: syntax=forth +) + : FIB ( n -- Fn ) 0 1 ( n a b ) 0 ( n a b i ) @@ -20,6 +23,6 @@ HELLO S" 10 FIB = " TELL 10 FIB .U -S" (Expected: 59)" TELL NEWLINE +SPACE S" (Expected: 59)" TELL NEWLINE TERMINATE diff --git a/main.asm b/main.asm index ae3f991..538039b 100644 --- a/main.asm +++ b/main.asm @@ -87,18 +87,12 @@ macro forth_asm label, name, immediate { .start: } -;; Define a Forth word that is implemented in Forth. (The body will be a list of -;; 'dq' statements.) -macro forth label, name, immediate { - header label, name, immediate - dq DOCOL -} - segment readable executable entry main -include "impl.asm" +include "impl.asm" ; Misc. subroutines +include "bootstrap.asm" ; Forth words encoded in Assembly main: cld ; Clear direction flag so LODSQ does the right thing. @@ -201,18 +195,6 @@ forth_asm EMIT, 'EMIT' popr rsi next -;; Prints a newline to standard output. -forth NEWLINE, 'NEWLINE' - dq LIT, $A - dq EMIT - dq EXIT - -;; Prints a space to standard output. -forth SPACE, 'SPACE' - dq LIT, ' ' - dq EMIT - dq EXIT - ;; Read a word from standard input and push it onto the stack as a pointer and a ;; size. The pointer is valid until the next call to READ_WORD. forth_asm READ_WORD, 'READ-WORD' @@ -238,11 +220,6 @@ forth_asm PARSE_NUMBER, 'PARSE-NUMBER' push rax ; Result next -forth READ_NUMBER, 'READ-NUMBER' - dq READ_WORD - dq PARSE_NUMBER - dq EXIT - ;; Takes a string (in the form of a pointer and a length on the stack) and ;; prints it to standard output. forth_asm TELL, 'TELL' @@ -297,55 +274,6 @@ forth_asm NOT_, 'NOT' push 1 next -;; The INTERPRET word reads and interprets user input. It's behavior depends on -;; the current STATE. It provides special handling for integers. -forth INTERPRET, 'INTERPRET' - ;; Read word - dq READ_WORD - dq PAIRDUP - ;; Stack is (word length word length). - dq FIND ; Try to find word - dq DUP_ - dq ZBRANCH, 8 * 22 ; Check if word is found - - ;; - Word is found - - - dq STATE, GET, ZBRANCH, 8 * 11 ; Check whether we are in compilation or immediate mode - - ;; (Word found, compilation mode) - dq DUP_, IS_IMMEDIATE, NOT_, ZBRANCH, 8 * 6 ; If the word is immediate, continue as we would in immediate mode - - ;; Otherwise, we want to compile this word - dq TCFA - dq COMMA - dq DROP, DROP - dq EXIT - - ;; (Word found, immediate mode) - ;; Execute word - dq TCFA - ;; Stack is (word length addr) - dq SWAP, DROP - dq SWAP, DROP - ;; Stack is (addr) - dq EXEC - dq EXIT - - ;; - No word is found, assume it is an integer literal - - ;; Stack is (word length addr) - dq DROP - dq PARSE_NUMBER - - dq STATE, GET, ZBRANCH, 8 * 5 ; Check whether we are in compilation or immediate mode - - ;; (Number, compilation mode) - dq LIT, LIT, COMMA - dq COMMA - dq EXIT - - ;; (Number, immediate mode) - dq EXIT - ;; .U prints the value on the stack as an unsigned integer in hexadecimal. forth_asm DOTU, '.U' mov [.length], 0 @@ -459,31 +387,6 @@ forth_asm TIMESMOD, '/MOD' push rdx ; a % b next -;; Get the location of the STATE variable. It can be set with '!' and read with -;; '@'. -forth STATE, 'STATE' - dq LIT, var_STATE - dq EXIT - -;; Get the location of the LATEST variable. It can be set with '!' and read with -;; '@'. -forth LATEST, 'LATEST' - dq LIT, latest_entry - dq EXIT - -;; Get the location at which compiled words are expected to be added. This -;; pointer is usually modified automatically when calling ',', but we can also -;; read it manually with 'HERE'. -forth HERE, 'HERE' - dq LIT, here - dq EXIT - -forth COMMA, ',' - dq HERE, GET, PUT ; Set the memory at the address pointed to by HERE - dq HERE, GET, LIT, 8, PLUS ; Calculate new address for HERE to point to - dq HERE, PUT ; Update HERE to point to the new address - dq EXIT - ;; Read user input until next " character is found. Push a string containing the ;; input on the stack as (buffer length). Note that the buffer is only valid ;; until the next call to S" and that no more than 255 character can be read. @@ -550,30 +453,6 @@ forth_asm CREATE, 'CREATE' next -;; Mark the last added word as immediate. -forth IMMEDIATE, 'IMMEDIATE', 1 - dq LIT, 1 - dq LATEST, GET - dq LIT, 8, PLUS - dq PUT_BYTE - dq EXIT - -;; Given the address of a word, return 0 if the given word is not immediate. -forth IS_IMMEDIATE, 'IMMEDIATE?' - dq LIT, 8, PLUS - dq GET_BYTE - dq EXIT - -;; Enter immediate mode, immediately -forth INTO_IMMEDIATE, '[', 1 - dq LIT, 0, STATE, PUT_BYTE - dq EXIT - -;; Enter compilation mode -forth OUTOF_IMMEDIATE, ']' - dq LIT, 1, STATE, PUT_BYTE - dq EXIT - forth_asm TICK, "'" lodsq push rax @@ -612,6 +491,20 @@ forth MAIN, 'MAIN' dq BRANCH, -8 * 2 dq TERMINATE +;; Built-in variables: + +forth STATE, 'STATE' + dq LIT, var_STATE + dq EXIT + +forth LATEST, 'LATEST' + dq LIT, latest_entry + dq EXIT + +forth HERE, 'HERE' + dq LIT, here + dq EXIT + segment readable writable ;; The LATEST variable holds a pointer to the word that was last added to the diff --git a/sys.f b/sys.f index 92efcb4..6b13ff9 100644 --- a/sys.f +++ b/sys.f @@ -76,3 +76,12 @@ EXIT [ SWAP 1 + SWAP 1 - DUP 0 = UNTIL DROP DROP ; + +: NEWLINE 10 EMIT ; +: SPACE 32 EMIT ; + +( Read a number from standard input. ) +: READ-NUMBER READ-WORD PARSE-NUMBER ; + +( vim: syntax=forth +)