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Author SHA1 Message Date
Virgil Dupras
5d5517ac44 forth: allow DEFINE's ";" to be at the start of a newline
Previous to this commit, DEFINE's algo would miss a ";" right after a newline.

This allows for a much nicer formatting+comment of core.fs.
2020-03-16 22:09:23 -04:00
Virgil Dupras
aec98a7a3a forth: separate COMPILE and [COMPILE] 2020-03-16 21:31:43 -04:00
Virgil Dupras
f404c2f4d0 forth: TIL forth source file extension is "fs" 2020-03-16 19:51:10 -04:00
6 changed files with 92 additions and 50 deletions

49
apps/forth/core.fs Normal file
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@ -0,0 +1,49 @@
: H HERE @ ;
: -^ SWAP - ;
: +! SWAP OVER @ + SWAP ! ;
: ALLOT HERE +! ;
: , H ! 2 ALLOT ;
: C, H C! 1 ALLOT ;
: BEGIN H ; IMMEDIATE
: COMPILE ' ['] LITN EXECUTE ['] , , ; IMMEDIATE
: AGAIN COMPILE (bbr) H -^ C, ; IMMEDIATE
: NOT 1 SWAP SKIP? EXIT 0 * ;
: ( BEGIN LITS ) WORD SCMP NOT SKIP? AGAIN ; IMMEDIATE
( Hello, hello, krkrkrkr... do you hear me?
Ah, voice at last! Some lines above need comments
BTW: Forth lines limited to 64 cols because of default
input buffer size in Collapse OS
COMPILE; Tough one. Get addr of caller word (example above
(bbr)) and then call LITN on it. However, LITN is an
immediate and has to be indirectly executed. Then, write
a reference to "," so that this word is written to HERE.
NOT: a bit convulted because we don't have IF yet )
: IF ( -- a | a: br cell addr )
COMPILE SKIP? ( if true, don't branch )
COMPILE (fbr)
H ( push a )
1 ALLOT ( br cell allot )
; IMMEDIATE
: THEN ( a -- | a: br cell addr )
DUP H -^ SWAP ( a-H a )
C!
; IMMEDIATE
: ELSE ( a1 -- a2 | a1: IF cell a2: ELSE cell )
COMPILE (fbr)
1 ALLOT
DUP H -^ SWAP ( a-H a )
C!
H 1 - ( push a. -1 for allot offset )
; IMMEDIATE
: ? @ . ;
: VARIABLE CREATE 2 ALLOT ;
: CONSTANT CREATE H ! DOES> @ ;
: = CMP NOT ;
: < CMP 0 1 - = ;
: > CMP 1 = ;

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@ -1,29 +0,0 @@
: H HERE @ ;
: -^ SWAP - ;
: +! SWAP OVER @ + SWAP ! ;
: ALLOT HERE +! ;
: , H ! 2 ALLOT ;
: C, H C! 1 ALLOT ;
: BEGIN H ; IMMEDIATE
: AGAIN ['] (bbr) , H -^ C, ; IMMEDIATE
: NOT 1 SWAP SKIP? EXIT 0 * ;
: ( BEGIN LITS ) WORD SCMP NOT SKIP? AGAIN ; IMMEDIATE
( Hello, hello, krkrkrkr... do you hear me?
Ah, voice at last! Some lines above need comments
BTW: Forth lines limited to 64 cols because of default
input buffer size in Collapse OS
NOT: a bit convulted because we don't have IF yet
IF true, skip following (fbr). Also, push br cell ref H,
to PS )
: IF ['] SKIP? , ['] (fbr) , H 1 ALLOT ; IMMEDIATE
( Subtract TOS from H to get offset to write to IF or ELSE's
br cell )
: THEN DUP H -^ SWAP C! ; IMMEDIATE
( write (fbr) addr, allot, then same as THEN )
: ELSE ['] (fbr) , 1 ALLOT DUP H -^ SWAP C! H 1 - ; IMMEDIATE
: ? @ . ;
: VARIABLE CREATE 2 ALLOT ;
: CONSTANT CREATE H ! DOES> @ ;
: = CMP NOT ;
: < CMP 0 1 - = ;
: > CMP 1 = ;

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@ -225,7 +225,7 @@ EXECUTE:
jp (hl) ; go!
.db "COMPILE"
.db "[COMPIL"
.dw EXECUTE
.db 1 ; IMMEDIATE
COMPILE:
@ -278,7 +278,7 @@ DEFINE:
ld (HERE), hl
.loop:
; did we reach ";"?
ld hl, (INPUTPOS)
call toword
ld a, (hl)
cp ';'
jr nz, .compile

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@ -42,13 +42,28 @@ directly, but as part of another word.
ALLOT n -- Move HERE by n bytes
C, b -- Write byte b in HERE and advance it.
CREATE x -- Create cell named x. Doesn't allocate a PF.
COMPILE x -- Compile word x and write it to HERE
[COMPILE] x -- Compile word x and write it to HERE
COMPILE x -- Meta compiles. Kind of blows the mind. See below.
CONSTANT x n -- Creates cell x that when called pushes its value
DOES> -- See description at top of file
IMMEDIATE -- Flag the latest defined word as immediate.
LITN n -- *I* Inserts number from TOS as a literal
VARIABLE c -- Creates cell x with 2 bytes allocation.
Compilation vs meta-compilation. When you compile a word with "[COMPILE] foo",
its straightforward: It writes down to HERE wither the address of the word or
a number literal.
When you *meta* compile, it's a bit more mind blowing. It fetches the address
of the word specified by the caller, then writes that number as a literal,
followed by a reference to ",".
Example: ": foo [COMPILE] bar;" is the equivalent of ": foo bar ;" if bar is
not an immediate. However, ": foo COMPILE bar ;" is the equivalent of
": foo ['] bar , ;". Got it?
Meta-compile only works with real words, not number literals.
*** Flow ***
Note about flow words: flow words can only be used in definitions. In the
INTERPRET loop, they don't have the desired effect because each word from the

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@ -4,25 +4,35 @@ pad:
ld a, PADDING
jp addHL
; Advance (INPUTPOS) until a non-whitespace is met. If needed,
; call fetchline.
; Set HL to newly set (INPUTPOS)
toword:
ld hl, (INPUTPOS)
; skip leading whitespace
dec hl ; offset leading "inc hl"
.loop:
inc hl
ld a, (hl)
or a
; When at EOL, fetch a new line directly
jr z, .empty
cp ' '+1
jr c, .loop
ret
.empty:
call fetchline
jr toword
; Read word from (INPUTPOS) and return, in HL, a null-terminated word.
; Advance (INPUTPOS) to the character following the whitespace ending the
; word.
; When we're at EOL, we call fetchline directly, so this call always returns
; a word.
readword:
ld hl, (INPUTPOS)
; skip leading whitespace
dec hl ; offset leading "inc hl"
.loop1:
inc hl
ld a, (hl)
or a
; When at EOL, fetch a new line directly
jr z, .empty
cp ' '+1
jr c, .loop1
call toword
push hl ; --> lvl 1. that's our result
.loop2:
.loop:
inc hl
ld a, (hl)
; special case: is A null? If yes, we will *not* inc A so that we don't
@ -30,7 +40,7 @@ readword:
or a
jr z, .noinc
cp ' '+1
jr nc, .loop2
jr nc, .loop
; we've just read a whitespace, HL is pointing to it. Let's transform
; it into a null-termination, inc HL, then set (INPUTPOS).
xor a
@ -40,9 +50,6 @@ readword:
ld (INPUTPOS), hl
pop hl ; <-- lvl 1. our result
ret ; Z set from XOR A
.empty:
call fetchline
jr readword
; Sets Z if (HL) == E and (HL+1) == D
HLPointsDE:

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@ -36,8 +36,8 @@ forth/stage1: forth/stage1.c $(OBJS) forth/forth0-bin.h
forth/stage1dbg: forth/stage1.c $(OBJS) forth/forth0-bin.h
$(CC) -DDEBUG forth/stage1.c $(OBJS) -o $@
forth/core.bin: $(APPS)/forth/core.fth forth/stage1
./forth/stage1 $(APPS)/forth/core.fth | tee $@ > /dev/null
forth/core.bin: $(APPS)/forth/core.fs forth/stage1
./forth/stage1 $(APPS)/forth/core.fs | tee $@ > /dev/null
forth/forth1.bin: forth/glue1.asm forth/core.bin $(ZASMBIN)
$(ZASMBIN) $(KERNEL) $(APPS) forth/core.bin < forth/glue1.asm | tee $@ > /dev/null