forth: split forth source into multiple files

apps/forth/core.fs

@@ -2,7 +2,6 @@
 : -^ SWAP - ;
 : +! SWAP OVER @ + SWAP ! ;
 : ALLOT HERE +! ;
-: , H ! 2 ALLOT ;
 : C, H C! 1 ALLOT ;
 : BEGIN H ; IMMEDIATE
 : COMPILE ' ['] LITN EXECUTE ['] , , ; IMMEDIATE
@@ -49,49 +48,3 @@
 : > CMP 1 = ;
 : / /MOD SWAP DROP ;
 : MOD /MOD DROP ;
-
-( Format numbers )
-( TODO FORGET this word )
-: PUSHDGTS
-    999 SWAP        ( stop indicator )
-    DUP 0 = IF '0' EXIT THEN    ( 0 is a special case )
-    BEGIN
-    DUP 0 = IF DROP EXIT THEN
-    10 /MOD         ( r q )
-    SWAP '0' + SWAP ( d q )
-    AGAIN
-;
-
-: .               ( n -- )
-    ( handle negative )
-    ( that "0 1 -" thing is because we don't parse negative
-      number correctly yet. )
-    DUP 0 < IF '-' EMIT 0 1 - * THEN
-    PUSHDGTS
-    BEGIN
-    DUP '9' > IF DROP EXIT THEN ( stop indicator, we're done )
-    EMIT
-    AGAIN
-;
-
-: PUSHDGTS
-    999 SWAP        ( stop indicator )
-    DUP 0 = IF '0' EXIT THEN    ( 0 is a special case )
-    BEGIN
-    DUP 0 = IF DROP EXIT THEN
-    16 /MOD         ( r q )
-    SWAP            ( r q )
-    DUP 9 > IF 10 - 'a' +
-    ELSE '0' + THEN ( q d )
-    SWAP ( d q )
-    AGAIN
-;
-
-: .X              ( n -- )
-    ( For hex display, there are no negatives )
-    PUSHDGTS
-    BEGIN
-    DUP 'f' > IF DROP EXIT THEN ( stop indicator, we're done )
-    EMIT
-    AGAIN
-;

apps/forth/dict.asm

@@ -119,8 +119,7 @@ LIT:
 	.db	0
 EXIT:
 	.dw nativeWord
-	call	popRS
-	ld	(IP), hl
+	call	popRSIP
 	jp	next
 
 ; ( R:I -- )
@@ -130,7 +129,6 @@ EXIT:
 	.db 0
 QUIT:
 	.dw nativeWord
-quit:
 	jp	forthRdLine
 
 	.db "ABORT"
@@ -283,9 +281,23 @@ PFETCH:
 	push	hl
 	jp	next
 
+	.db	","
+	.fill	6
+	.dw	PFETCH
+	.db	0
+WR:
+	.dw	nativeWord
+	pop	de
+	call	chkPS
+	ld	hl, (HERE)
+	call	DEinHL
+	ld	(HERE), hl
+	jp	next
+
+
 ; ( addr -- )
 	.db "EXECUTE"
-	.dw PFETCH
+	.dw WR
 	.db 0
 EXECUTE:
 	.dw nativeWord
@@ -304,41 +316,34 @@ EXECUTE:
 	.dw	EXECUTE
 	.db	1		; IMMEDIATE
 COMPILE:
-	.dw	nativeWord
-	call	readword
-	call	find
-	jr	nz, .maybeNum
-	ex	de, hl
-	call	HLisIMMED
-	jr	z, .immed
-	ex	de, hl
-	call	.writeDE
-	jp	next
+	.dw	compiledWord
+	.dw	FIND_
+	.dw	CSKIP
+	.dw	.maybeNum
+	.dw	DUP
+	.dw	ISIMMED
+	.dw	CSKIP
+	.dw	.word
+	; is immediate. just execute.
+	.dw	EXECUTE
+	.dw	EXIT
+
+	.db	0b10		; UNWORD
+.word:
+	.dw	compiledWord
+	.dw	WR
+	.dw	R2P		; exit COMPILE
+	.dw	DROP
+	.dw	EXIT
+
+	.db	0b10		; UNWORD
 .maybeNum:
-	push	hl		; --> lvl 1. save string addr
-	call	parseLiteral
-	pop	hl		; <-- lvl 1
-	jr	nz, .undef
-	; a valid number in DE!
-	ex	de, hl
-	ld	de, NUMBER
-	call	.writeDE
-	ex	de, hl		; number in DE
-	call	.writeDE
-	jp	next
-.undef:
-	call	printstr
-	jp	abortUnknownWord
-.immed:
-	push	hl
-	jp	EXECUTE+2
-.writeDE:
-	push	hl
-	ld	hl, (HERE)
-	call	DEinHL
-	ld	(HERE), hl
-	pop	hl
-	ret
+	.dw	compiledWord
+	.dw	PARSEI
+	.dw	LITN
+	.dw	R2P		; exit COMPILE
+	.dw	DROP
+	.dw	EXIT
 
 
 	.db	":"
@@ -381,8 +386,7 @@ DEFINE:
 .retRef:
 	.dw	$+2
 	.dw	$+2
-	call	popRS
-	ld	(IP), hl
+	call	popRSIP
 	jr	.loop
 
 
@@ -418,10 +422,28 @@ IMMEDIATE:
 	set	FLAG_IMMED, (hl)
 	jp	next
 
+
+	.db	"IMMED?"
+	.fill	1
+	.dw	IMMEDIATE
+	.db	0
+ISIMMED:
+	.dw	nativeWord
+	pop	hl
+	call	chkPS
+	dec	hl
+	ld	de, 0
+	bit	FLAG_IMMED, (hl)
+	jr	z, .notset
+	inc	de
+.notset:
+	push	de
+	jp	next
+
 ; ( n -- )
 	.db	"LITN"
 	.fill	3
-	.dw	IMMEDIATE
+	.dw	ISIMMED
 	.db	1		; IMMEDIATE
 LITN:
 	.dw nativeWord
@@ -524,9 +546,61 @@ WORD:
 	push	hl
 	jp	next
 
+
+	.db	"(parsed"
+	.dw	WORD
+	.db	0
+PARSED:
+	.dw	nativeWord
+	pop	hl
+	call	chkPS
+	call	parseDecimal
+	jr	z, .success
+	; error
+	ld	de, 0
+	push	de	; dummy
+	push	de	; flag
+	jp	next
+.success:
+	push	de
+	ld	de, 1		; flag
+	push	de
+	jp	next
+
+
+	.db	"(parse)"
+	.dw	PARSED
+	.db	0
+PARSE:
+	.dw	compiledWord
+	.dw	PARSED
+	.dw	CSKIP
+	.dw	.error
+	; success, stack is already good, we can exit
+	.dw	EXIT
+
+	.db	0b10		; UNWORD
+.error:
+	.dw	compiledWord
+	.dw	LIT
+	.db	"unknown word", 0
+	.dw	PRINT
+	.dw	ABORT
+
+
+; Indirect parse caller. Reads PARSEPTR and calls
+	.db	0b10		; UNWORD
+PARSEI:
+	.dw	compiledWord
+	.dw	PARSEPTR_
+	.dw	FETCH
+	.dw	EXECUTE
+	.dw	EXIT
+
+
 	.db "CREATE"
 	.fill 1
-	.dw WORD
+	.dw PARSE
 	.db 0
 CREATE:
 	.dw nativeWord
@@ -554,9 +628,16 @@ CURRENT_:
 	.dw sysvarWord
 	.dw CURRENT
 
+	.db "(parse*"
+	.dw CURRENT_
+	.db 0
+PARSEPTR_:
+	.dw sysvarWord
+	.dw PARSEPTR
+
 	.db	"IN>"
 	.fill	4
-	.dw	CURRENT_
+	.dw	PARSEPTR_
 	.db	0
 INP:
 	.dw	sysvarWord

apps/forth/dictionary.txt

@@ -48,6 +48,7 @@ CREATE x    --              Create cell named x. Doesn't allocate a PF.
 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
+IMMED?      a -- f          Checks whether wordref at a is immediate.
 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.
@@ -150,6 +151,33 @@ wait until another line is entered.
 KEY input, however, is direct. Regardless of the input buffer's state, KEY will
 return the next typed key.
 
+PARSING AND BOOTSTRAP: Parsing number literal is a very "core" activity of
+Forth, and therefore generally seen as having to be implemented in native code.
+However, Collapse OS' Forth supports many kinds of literals: decimal, hex, char,
+binary. This incurs a significant complexity penalty.
+
+What if we could implement those parsing routines in Forth? "But it's a core
+routine!" you say. Yes, but here's the deal: at its native core, only decimal
+parsing is supported. It lives in the "(parsed)" word. The interpreter's main
+loop is initially set to simply call that word.
+
+However, in core.fs, "(parsex)", "(parsec)" and "(parseb)" are implemented, in
+Forth, then "(parse)", which goes through them all is defined. Then, "(parsef)",
+which is the variable in which the interpreter's word pointer is set, is
+updated to that new "(parse)" word.
+
+This way, we have a full-featured (and extensible) parsing with a tiny native
+core.
+
+(parse)     a -- n          Parses string at a as a number and push the result
+                            in n as well as whether parsing was a success in f
+                            (false = failure, true = success)
+(parse.)    a -- n f        Sub-parsing words. They all have the same signature.
+                            Parses string at a as a number and push the result
+                            in n as well as whether parsing was a success in f
+                            (0 = failure, 1 = success)
+(parse*)    -- a            Variable holding the current pointer for system
+                            number parsing. By default, (parse).
 (print)     a --            Print string at addr a.
 .           n --            Print n in its decimal form
 .X          n --            Print n in its hexadecimal form. In hex, numbers

apps/forth/fmt.fs

@@ -0,0 +1,46 @@
+( requires core, parse )
+
+( TODO FORGET this word )
+: PUSHDGTS
+    999 SWAP        ( stop indicator )
+    DUP 0 = IF '0' EXIT THEN    ( 0 is a special case )
+    BEGIN
+    DUP 0 = IF DROP EXIT THEN
+    10 /MOD         ( r q )
+    SWAP '0' + SWAP ( d q )
+    AGAIN
+;
+
+: .               ( n -- )
+    ( handle negative )
+    ( that "0 1 -" thing is because we don't parse negative
+      number correctly yet. )
+    DUP 0 < IF '-' EMIT 0 1 - * THEN
+    PUSHDGTS
+    BEGIN
+    DUP '9' > IF DROP EXIT THEN ( stop indicator, we're done )
+    EMIT
+    AGAIN
+;
+
+: PUSHDGTS
+    999 SWAP        ( stop indicator )
+    DUP 0 = IF '0' EXIT THEN    ( 0 is a special case )
+    BEGIN
+    DUP 0 = IF DROP EXIT THEN
+    16 /MOD         ( r q )
+    SWAP            ( r q )
+    DUP 9 > IF 10 - 'a' +
+    ELSE '0' + THEN ( q d )
+    SWAP ( d q )
+    AGAIN
+;
+
+: .X              ( n -- )
+    ( For hex display, there are no negatives )
+    PUSHDGTS
+    BEGIN
+    DUP 'f' > IF DROP EXIT THEN ( stop indicator, we're done )
+    EMIT
+    AGAIN
+;

apps/forth/main.asm

@@ -25,7 +25,11 @@
 .equ	IP		@+2
 ; Pointer to where we currently are in the interpretation of the current line.
 .equ	INPUTPOS	@+2
-; Buffer where we compile the current input line. Same size as STDIO_BUFSIZE.
+; Pointer to the system's number parsing function. It points to then entry that
+; had the "(parse)" name at startup. During stage0, it's out builtin PARSE,
+; but at stage1, it becomes "(parse)" from core.fs. It can also be changed at
+; runtime.
+.equ	PARSEPTR	@+2
 .equ	FORTH_RAMEND	@+2
 
 ; (HERE) usually starts at RAMEND, but in certain situations, such as in stage0,
@@ -84,6 +88,10 @@ forthMain:
 	ld	(INPUTPOS), hl
 	xor	a
 	ld	(hl), a
+	; Set up PARSEPTR
+	ld	hl, PARSE-CODELINK_OFFSET
+	call	find
+	ld	(PARSEPTR), de
 forthRdLine:
 	ld	hl, msgOk
 	call	printstr
@@ -96,32 +104,24 @@ forthRdLineNoOk:
 
 	.db	0b10		; UNWORD
 INTERPRET:
-	.dw	nativeWord
-	pop	hl		; from WORD
-	ld	a, (hl)		; special case: empty
-	or	a
-	jp	z, next
-	call	find
-	jr	nz, .maybeNum
-	; regular word
-	push	de
-	jp	EXECUTE+2
+	.dw	compiledWord
+	.dw	FIND_
+	.dw	CSKIP
+	.dw	.maybeNum
+	; It's a word, execute it
+	.dw	EXECUTE
+	.dw	EXIT
+
 .maybeNum:
-	push	hl		; --> lvl 1. save string addr
-	call	parseLiteral
-	pop	hl		; <-- lvl 1
-	jr	nz, .undef
-	; a valid number in DE!
-	push	de
-	jp	next
-.undef:
-	call	printstr
-	jp	abortUnknownWord
+	.dw	compiledWord
+	.dw	PARSEI
+	.dw	R2P		; exit INTERPRET
+	.dw	DROP
+	.dw	EXIT
 
 	.db	0b10		; UNWORD
 MAINLOOP:
 	.dw	compiledWord
-	.dw	WORD
 	.dw	INTERPRET
 	.dw	INP
 	.dw	FETCH

apps/forth/parse.fs

@@ -0,0 +1,18 @@
+( requires core )
+
+: (parsec)          ( a -- n f )
+    ( apostrophe is ASCII 39 )
+    DUP C@ 39 = NOT IF 0 EXIT THEN      ( -- a 0 )
+    DUP 2 + C@ 39 = NOT IF 0 EXIT THEN  ( -- a 0 )
+    ( surrounded by apos, good, return )
+    1 + C@ 1       ( -- n 1 )
+;
+
+: (parse)           ( a -- n )
+    (parsec) NOT SKIP? EXIT
+    (parsed) NOT SKIP? EXIT
+    ( nothing works )
+    ABORT" unknown word! "
+;
+
+' (parse) (parse*) !

apps/forth/stack.asm

@@ -25,6 +25,11 @@ popRS:
 	dec ix
 	ret
 
+popRSIP:
+	call	popRS
+	ld	(IP), hl
+	ret
+
 ; Skip the next two bytes in RS' TOS
 skipRS:
 	push	hl

apps/forth/util.asm

@@ -115,25 +115,6 @@ multDEBC:
 	jr	nz, .loop
 	ret
 
-; Parse the hex char at A and extract it's 0-15 numerical value. Put the result
-; in A.
-;
-; On success, the carry flag is reset. On error, it is set.
-parseHex:
-	; First, let's see if we have an easy 0-9 case
-
-	add 	a, 0xc6	; maps '0'-'9' onto 0xf6-0xff
-	sub 	0xf6	; maps to 0-9 and carries if not a digit
-	ret	nc
-
-	and 	0xdf		; converts lowercase to uppercase
-	add	a, 0xe9		; map 0x11-x017 onto 0xFA - 0xFF
-	sub 	0xfa		; map onto 0-6
-	ret 	c
-	; we have an A-F digit
-	add	a, 10		; C is clear, map back to 0xA-0xF
-	ret
-
 ; Parse string at (HL) as a decimal value and return value in DE.
 ; Reads as many digits as it can and stop when:
 ; 1 - A non-digit character is read
@@ -156,7 +137,6 @@ parseDecimal:
 	; During this routine, we switch between HL and its shadow. On one side,
 	; we have HL the string pointer, and on the other side, we have HL the
 	; numerical result. We also use EXX to preserve BC, saving us a push.
-parseDecimalSkip:	; enter here to skip parsing the first digit
 	exx		; HL as a result
 	ld	h, 0
 	ld	l, a	; load first digit in without multiplying
@@ -201,130 +181,6 @@ parseDecimalSkip:	; enter here to skip parsing the first digit
 	cp	a	; ensure Z
 	ret
 
-; Parse string at (HL) as a hexadecimal value without the "0x" prefix and
-; return value in DE.
-; HL is advanced to the character following the last successfully read char.
-; Sets Z on success.
-parseHexadecimal:
-	ld	a, (hl)
-	call	parseHex	; before "ret c" is "sub 0xfa" in parseHex
-				; so carry implies not zero
-	ret 	c	; we need at least one char
-	push	bc
-	ld	de, 0
-	ld	b, d
-	ld	c, d
-
-; The idea here is that the 4 hex digits of the result can be represented "bdce",
-; where each register holds a single digit. Then the result is simply
-; e = (c << 4) | e,	 d = (b << 4) | d
-; However, the actual string may be of any length, so when loading in the most
-; significant digit, we don't know which digit of the result it actually represents
-; To solve this, after a digit is loaded into a (and is checked for validity),
-; all digits are moved along, with e taking the latest digit.
-.loop:
-	dec 	b
-	inc 	b	; b should be 0, else we've overflowed
-	jr	nz, .end	; Z already unset if overflow
-	ld 	b, d
-	ld 	d, c
-	ld 	c, e
-	ld 	e, a
-	inc 	hl
-	ld 	a, (hl)
-	call 	parseHex
-	jr 	nc, .loop
-	ld 	a, b
-	add	a, a  \ add a, a \ add a, a \ add a, a
-	or 	d
-	ld 	d, a
-
-	ld 	a, c
-	add	a, a  \ add a, a \ add a, a \ add a, a
-	or 	e
-	ld 	e, a
-	xor	a	; ensure z
-
-.end:
-	pop	bc
-	ret
-
-
-; Parse string at (HL) as a binary value (010101) without the "0b" prefix and
-; return value in E. D is always zero.
-; HL is advanced to the character following the last successfully read char.
-; Sets Z on success.
-parseBinaryLiteral:
-	ld	de, 0
-.loop:
-	ld	a, (hl)
-	add	a, 0xff-'1'
-	sub	0xff-1
-	jr	c, .end
-	rlc	e	; sets carry if overflow, and affects Z
-	ret	c	; Z unset if carry set, since bit 0 of e must be set
-	add	a, e
-	ld	e, a
-	inc	hl
-	jr	.loop
-.end:
-	; HL is properly set
-	xor	a		; ensure Z
-	ret
-
-; Parses the string at (HL) and returns the 16-bit value in DE. The string
-; can be a decimal literal (1234), a hexadecimal literal (0x1234) or a char
-; literal ('X').
-; HL is advanced to the character following the last successfully read char.
-;
-; As soon as the number doesn't fit 16-bit any more, parsing stops and the
-; number is invalid. If the number is valid, Z is set, otherwise, unset.
-parseLiteral:
-	ld	de, 0		; pre-fill
-	ld	a, (hl)
-	cp	0x27		; apostrophe
-	jr	z, .char
-
-	; inline parseDecimalDigit
-	add 	a, 0xc6	; maps '0'-'9' onto 0xf6-0xff
-	sub 	0xf6	; maps to 0-9 and carries if not a digit
-	ret	c
-	; a already parsed so skip first few instructions of parseDecimal
-	jp	nz, parseDecimalSkip
-	; maybe hex, maybe binary
-	inc	hl
-	ld	a, (hl)
-	inc	hl		; already place it for hex or bin
-	cp	'x'
-	jr	z, parseHexadecimal
-	cp	'b'
-	jr	z, parseBinaryLiteral
-	; nope, just a regular decimal
-	dec	hl \ dec hl
-	jp	parseDecimal
-
-; Parse string at (HL) and, if it is a char literal, sets Z and return
-; corresponding value in E. D is always zero.
-; HL is advanced to the character following the last successfully read char.
-;
-; A valid char literal starts with ', ends with ' and has one character in the
-; middle. No escape sequence are accepted, but ''' will return the apostrophe
-; character.
-.char:
-	inc	hl
-	ld	e, (hl)		; our result
-	inc	hl
-	cp	(hl)
-	; advance HL and return if good char
-	inc	hl
-	ret	z
-
-	; Z unset and there's an error
-	; In all error conditions, HL is advanced by 3. Rewind.
-	dec	hl \ dec hl \ dec hl
-	; NZ already set
-	ret
-
 ; *** Forth-specific part ***
 ; Return address of scratchpad in HL
 pad:
@@ -519,14 +375,6 @@ HLisIMMED:
 	; We need an invert flag. We want to Z to be set when flag is non-zero.
 	jp	toggleZ
 
-; Sets Z if wordref at (HL) is of the IMMEDIATE type
-HLPointsIMMED:
-	push	hl
-	call	intoHL
-	call	HLisIMMED
-	pop	hl
-	ret
-
 ; Sets Z if wordref at HL is of the UNWORD type
 HLisUNWORD:
 	dec	hl

emul/Makefile

@@ -6,6 +6,9 @@ ZASMBIN = zasm/zasm
 AVRABIN = zasm/avra
 SHELLAPPS = zasm ed
 SHELLTGTS = ${SHELLAPPS:%=cfsin/%}
+# Those Forth source files are in a particular order
+FORTHSRCS = core.fs parse.fs fmt.fs
+FORTHSRC_PATHS = ${FORTHSRCS:%=$(APPS)/forth/%}
 CFSIN_CONTENTS = $(SHELLTGTS) cfsin/user.h
 OBJS = emul.o libz80/libz80.o
 SHELLOBJS = $(OBJS) $(CFSPACK_OBJ)
@@ -36,8 +39,8 @@ 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.fs forth/stage1
-	./forth/stage1 $(APPS)/forth/core.fs | tee $@ > /dev/null
+forth/core.bin: $(FORTHSRC_PATHS) forth/stage1
+	cat $(FORTHSRC_PATHS) | ./forth/stage1 | 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

emul/forth/stage1.c

@@ -35,11 +35,10 @@ that wordref offsets correspond.
 #define CURRENT 0xe702
 
 static int running;
-static FILE *fp;
 
 static uint8_t iord_stdio()
 {
-    int c = getc(fp);
+    int c = getc(stdin);
     if (c == EOF) {
         running = 0;
     }
@@ -57,20 +56,6 @@ static void iowr_stdio(uint8_t val)
 
 int main(int argc, char *argv[])
 {
-#ifdef DEBUG
-    fp = stdin;
-#else
-    if (argc == 2) {
-        fp = fopen(argv[1], "r");
-        if (fp == NULL) {
-            fprintf(stderr, "Can't open %s\n", argv[1]);
-            return 1;
-        }
-    } else {
-        fprintf(stderr, "Usage: ./stage0 filename\n");
-        return 1;
-    }
-#endif
     Machine *m = emul_init();
     m->ramstart = RAMSTART;
     m->iord[STDIO_PORT] = iord_stdio;
@@ -84,8 +69,6 @@ int main(int argc, char *argv[])
 
     while (running && emul_step());
 
-    fclose(fp);
-
 #ifndef DEBUG
     // We're done, now let's spit dict data
     // let's start with LATEST spitting.