zasm: add support for labels!

apps/zasm/instr.asm

@@ -115,27 +115,23 @@ parseIXY:
 	pop	hl
 	ret
 
-; Returns length of string at (HL) in A.
-strlen:
-	push	bc
-	push	hl
-	ld	bc, 0
-	ld	a, 0	; look for null char
-.loop:
-	cpi
-	jp	z, .found
-	jr	.loop
-.found:
-	; How many char do we have? the (NEG BC)-1, which started at 0 and
-	; decreased at each CPI call. In this routine, we stay in the 8-bit
-	; realm, so C only.
-	ld	a, c
-	neg
-	dec	a
-	pop	hl
-	pop	bc
+; Parse string in (HL) and return its numerical value whether its a number
+; literal or a symbol. Returns value in IX.
+; Sets Z if number or symbol is valid, unset otherwise.
+parseNumberOrSymbol:
+	call	parseNumber
+	ret	z
+	; Not a number. Try symbol
+	push	de
+	call	symGetVal
+	jr	nz, .notfound	; Z already unset
+	; Found! value in DE. We need it in IX
+	ld	ixh, d
+	ld	ixl, e
+	; Z already set
+.notfound:
+	pop	de
 	ret
-
 ; find argspec for string at (HL). Returns matching argspec in A.
 ; Return value 0xff holds a special meaning: arg is not empty, but doesn't match
 ; any argspec (A == 0 means arg is empty). A return value of 0xff means an
@@ -174,7 +170,7 @@ parseArg:
 	call	enterParens
 	jr	z, .withParens
 	; (HL) has no parens
-	call	parseNumber
+	call	parseNumberOrSymbol
 	jr	nz, .nomatch
 	; We have a proper number in no parens. Number in IX.
 	ld	a, 'N'
@@ -198,7 +194,7 @@ parseArg:
 .notY:
 	ld	c, 'x'
 .parseNumberInParens:
-	call	parseNumber
+	call	parseNumberOrSymbol
 	jr	nz, .nomatch
 	; We have a proper number in parens. Number in IX
 	ld	a, c	; M, x, or y

apps/zasm/literal.asm

@@ -6,9 +6,10 @@ parseDecimal:
 	; First, let's see if we have an easy 0-9 case
 	cp	'0'
 	ret	c	; if < '0', we have a problem
-	cp	'9'+1
-	; We are in the 0-9 range
-	sub	a, '0'		; C is clear
+	sub	a, '0'		; our value now is valid if it's < 10
+	cp	10		; on success, C is set, which is the opposite
+				; of what we want
+	ccf			; invert C flag
 	ret
 
 ; Parses the string at (HL) and returns the 16-bit value in IX.

apps/zasm/main.asm

@@ -2,9 +2,12 @@
 ; blockdev
 ; JUMP_STRNCMP
 ; JUMP_ADDDE
+; JUMP_ADDHL
 ; JUMP_UPCASE
 ; JUMP_UNSETZ
 ; JUMP_INTODE
+; JUMP_FINDCHAR
+; RAMSTART	(where we put our variables in RAM)
 
 ; *** Code ***
 ; Read file through GetC routine pointer at HL and outputs its upcodes through
@@ -12,6 +15,8 @@
 main:
 	ld	(ioGetCPtr), hl
 	ld	(ioPutCPtr), de
+	ld	hl, 0
+	ld	(curOutputOffset), hl
 .loop:
 	call	ioReadLine
 	or	a		; is A 0?
@@ -28,10 +33,21 @@ main:
 #include "literal.asm"
 #include "instr.asm"
 #include "directive.asm"
+.equ	SYM_RAMSTART	RAMSTART
+#include "symbol.asm"
 
-; Parse line in (HL), write the resulting opcode(s) in (DE) and returns the
-; number of written bytes in IXL. Advances HL where tokenization stopped and DE
-; to where we should write the next upcode.
+; Increase (curOutputOffset) by A
+incOutputOffset:
+	push	de
+	ld	de, (curOutputOffset)
+	call	JUMP_ADDDE
+	ld	(curOutputOffset), de
+	pop	de
+	ret
+
+; Parse line in (HL), write the resulting opcode(s) in (DE) and increases
+; (curOutputOffset) by the number of bytes written. Advances HL where
+; tokenization stopped and DE to where we should write the next upcode.
 ; Sets Z if parse was successful, unset if there was an error or EOF.
 parseLine:
 	push	bc
@@ -42,6 +58,8 @@ parseLine:
 	jr	z, .instr
 	cp	TOK_DIRECTIVE
 	jr	z, .direc
+	cp	TOK_LABEL
+	jr	z, .label
 	cp	TOK_EMPTY
 	jr	z, .success	; empty line? do nothing but don't error out.
 	jr	.error		; token not supported
@@ -50,6 +68,7 @@ parseLine:
 	call	parseInstruction
 	or	a	; is zero?
 	jr	z, .error
+	call	incOutputOffset
 	ld	b, a
 	ld	hl, instrUpcode
 .loopInstr:
@@ -61,6 +80,7 @@ parseLine:
 .direc:
 	ld	a, c		; D_*
 	call	parseDirective
+	call	incOutputOffset
 	ld	b, a
 	ld	hl, direcData
 .loopDirec:
@@ -68,15 +88,24 @@ parseLine:
 	call	ioPutC
 	inc	hl
 	djnz	.loopDirec
+	jr	.success
+.label:
+	; The string in (scratchpad) is a label with its trailing ':' removed.
+	ld	hl, scratchpad
+	ld	de, (curOutputOffset)
+	call	symRegister
+
 	jr	.success
 .success:
-	ld	ixl, a
 	xor	a		; ensure Z
 	jr	.end
 .error:
-	xor	ixl
 	call	JUMP_UNSETZ
 .end:
 	pop	bc
 	ret
 
+; *** Variables ***
+; The offset where we currently are with regards to outputting opcodes
+curOutputOffset:
+	.fill	2

apps/zasm/parse.asm

@@ -1,6 +1,7 @@
 ; *** Consts ***
 TOK_INSTR	.equ	0x01
 TOK_DIRECTIVE	.equ	0x02
+TOK_LABEL	.equ	0x03
 TOK_EMPTY	.equ	0xfe	; not a bad token, just an empty line
 TOK_BAD		.equ	0xff
 
@@ -34,6 +35,34 @@ isSepOrLineEnd:
 	call	isLineEndOrComment
 	ret
 
+; Checks whether string at (HL) is a label, that is, whether it ends with a ":"
+; Sets Z if yes, unset if no.
+;
+; If it's a label, we change the trailing ':' char with a null char. It's a bit
+; dirty, but it's the easiest way to proceed.
+isLabel:
+	push	hl
+	ld	a, ':'
+	call	JUMP_FINDCHAR
+	ld	a, (hl)
+	cp	':'
+	jr	nz, .nomatch
+	; We also have to check that it's our last char.
+	inc	hl
+	ld	a, (hl)
+	or	a		; cp 0
+	jr	nz, .nomatch	; not a null char following the :. no match.
+	; We have a match!
+	; Remove trailing ':'
+	xor	a		; Z is set
+	ld	(hl), a
+	jr	.end
+.nomatch:
+	call	JUMP_UNSETZ
+.end:
+	pop	hl
+	ret
+
 ; read word in (HL) and put it in (scratchpad), null terminated, for a maximum
 ; of SCRATCHPAD_SIZE-1 characters. As a result, A is the read length. HL is
 ; advanced to the next separator char.
@@ -90,6 +119,8 @@ tokenize:
 	call	readWord
 	push	hl		; Save advanced HL for later
 	ld	hl, scratchpad
+	call	isLabel
+	jr	z, .label
 	call	getInstID
 	jr	z, .instr
 	call	getDirectiveID
@@ -102,6 +133,9 @@ tokenize:
 	jr	.end
 .direc:
 	ld	b, TOK_DIRECTIVE
+	jr	.end
+.label:
+	ld	b, TOK_LABEL
 .end:
 	ld	c, a
 	pop	hl

apps/zasm/symbol.asm

@@ -0,0 +1,184 @@
+; Manages both constants and labels within a same namespace and registry.
+
+; *** Constants ***
+; Duplicate symbol in registry
+.equ	SYM_ERR_DUPLICATE	0x01
+; Symbol registry buffer is full
+.equ	SYM_ERR_FULLBUF		0x02
+
+; Maximum number of symbols we can have in the registry
+.equ	SYM_MAXCOUNT	0x100
+
+; Size of the symbol name buffer size. This is a pool. There is no maximum name
+; length for a single symbol, just a maximum size for the whole pool.
+.equ	SYM_BUFSIZE	0x1000
+
+; *** Variables ***
+; Each symbol is mapped to a word value saved here.
+.equ	SYM_VALUES	SYM_RAMSTART
+
+; A list of symbol names separated by null characters. When we encounter a
+; symbol name and want to get its value, we search the name here, retrieve the
+; index of the name, then go get the value at that index in SYM_VALUES.
+.equ	SYM_NAMES	SYM_VALUES+(SYM_MAXCOUNT*2)
+
+.equ	SYM_RAMEND	SYM_NAMES+SYM_BUFSIZE
+
+; *** Code ***
+
+; Place HL at the end of SYM_NAMES end (that is, at the point where we have two
+; consecutive null chars. We return the index of that new name in A.
+; If we're within bounds, Z is set, otherwise unset.
+symNamesEnd:
+	push	bc
+	push	de
+
+	ld	b, 0
+	ld	hl, SYM_NAMES
+	ld	de, SYM_NAMES+SYM_BUFSIZE
+.loop:
+	ld	a, (hl)
+	or	a		; cp 0
+	jr	z, .success	; We've reached the end, Z is set, all good
+	xor	a
+	call	JUMP_FINDCHAR	; find next null char
+	; go to the char after it.
+	inc	hl
+	; Are we out of bounds?
+	call	cpHLDE
+	jr	nc, .outOfBounds	; HL >= DE
+	djnz	.loop
+	; exhausted djnz? out of bounds
+.outOfBounds:
+	call	JUMP_UNSETZ
+	jr	.end
+.success:
+	; Our index is 0 - B (if B is, for example 0xfd, A is 0x3)
+	xor	a
+	sub	b
+	cp	a		; ensure Z
+.end:
+	pop	de
+	pop	bc
+	ret
+
+; Register label in (HL) (minus the ending ":") into the symbol registry and
+; set its value in that registry to DE.
+; If successful, Z is set and A is the symbol index. Otherwise, Z is unset and
+; A is an error code (SYM_ERR_*).
+symRegister:
+	push	hl
+	push	bc
+	push	de
+
+	; First, let's get our strlen
+	call	strlen
+	ld	c, a		; save that strlen for later
+
+	ex	hl, de		; symbol to add is now in DE
+	call	symNamesEnd
+	jr	nz, .error
+	; A is our index. Save it
+	ex	af, af'
+	; Is our new name going to make us go out of bounds?
+	push	hl
+	push	de
+		ld	de, SYM_NAMES+SYM_BUFSIZE
+		ld	a, c
+		call	JUMP_ADDHL
+		call	cpHLDE
+	pop	de
+	pop	hl
+	jr	nc, .error	; HL >= DE
+
+	; HL point to where we want to add the string
+	ex	hl, de		; symbol to add in HL, dest in DE
+	; Copy HL into DE until we reach null char
+	; C already have our strlen (minus null char). Let's prepare BC for
+	; a LDIR.
+	inc	c	; include null char
+	ld	b, 0
+	ldir		; copy C chars from HL to DE
+
+	; I'd say we're pretty good just about now. What we need to do is to
+	; save the value in our original DE that is just on top of the stack
+	; into the proper index in SYM_VALUES. Our index, remember, is
+	; currently in A'.
+	ex	af, af'
+	pop	de
+	push	de	; push it right back to avoid stack imbalance
+	ld	hl, SYM_VALUES
+	call	JUMP_ADDHL
+	call	JUMP_ADDHL	; twice because our values are words
+
+	; Everything is set! DE is our value HL points to the proper index in
+	; SYM_VALUES. Let's just write it (little endian).
+	ld	(hl), e
+	inc	hl
+	ld	(hl), d
+.error:
+	; Z already unset
+	pop	de
+	pop	bc
+	pop	hl
+	ret
+
+; Find name (HL) in SYM_NAMES and returns matching index in A.
+; If we find something, Z is set, otherwise unset.
+symFind:
+	push	hl
+	push	bc
+	push	de
+
+	; First, what's our strlen?
+	call	strlen
+	ld	c, a		; let's save that
+
+	ex	hl, de		; it's easier if HL is haystack and DE is
+				; needle.
+	ld	b, 0
+	ld	hl, SYM_NAMES
+.loop:
+	ld	a, (hl)
+	or	a		; cp 0
+	jr	z, .nomatch
+	ld	a, c
+	call	JUMP_STRNCMP
+	jr	z, .match
+	; ok, next!
+	xor	a
+	call	JUMP_FINDCHAR	; find next null char
+	; go to the char after it.
+	inc	hl
+	djnz	.loop
+	; exhausted djnz? no match
+.nomatch:
+	call	JUMP_UNSETZ
+	jr	.end
+.match:
+	; Our index is 0 - B (if B is, for example 0xfd, A is 0x3)
+	xor	a
+	sub	b
+	cp	a		; ensure Z
+.end:
+	pop	de
+	pop	bc
+	pop	hl
+	ret
+
+; Return value associated with symbol string in (HL) into DE.
+; Sets Z on success, unset on error.
+symGetVal:
+	call	symFind
+	ret	nz	; not found
+	; our index is in A. Let's fetch the proper value
+	push	hl
+	ld	hl, SYM_VALUES
+	call	JUMP_ADDHL
+	call	JUMP_ADDHL	; twice because our values are words
+	ld	e, (hl)
+	inc	hl
+	ld	d, (hl)
+	pop	hl
+	cp	a		; ensure Z
+	ret

apps/zasm/tests/test1.asm

@@ -1,7 +1,11 @@
 	; comment
 	add	a, b	; comment
+label1:
 	inc	a	; comment
 	; comment
 	.db	42
+label2:
 	.dw	42
 	.dw	3742
+	ld	a, (label1)
+	ld	hl, label2

apps/zasm/util.asm

@@ -12,6 +12,37 @@ callHL:
 	jp	(hl)
 	ret
 
+; Compare HL with DE and sets Z and C in the same way as a regular cp X where
+; HL is A and DE is X.
+cpHLDE:
+	ld	a, h
+	cp	d
+	ret	nz	; if not equal, flags are correct
+	ld	a, l
+	cp	e
+	ret		; flags are correct
+
+; Returns length of string at (HL) in A.
+strlen:
+	push	bc
+	push	hl
+	ld	bc, 0
+	ld	a, 0	; look for null char
+.loop:
+	cpi
+	jp	z, .found
+	jr	.loop
+.found:
+	; How many char do we have? the (NEG BC)-1, which started at 0 and
+	; decreased at each CPI call. In this routine, we stay in the 8-bit
+	; realm, so C only.
+	ld	a, c
+	neg
+	dec	a
+	pop	hl
+	pop	bc
+	ret
+
 ; If string at (HL) starts with ( and ends with ), "enter" into the parens
 ; (advance HL and put a null char at the end of the string) and set Z.
 ; Otherwise, do nothing and reset Z.

tools/emul/zasm_glue.asm

@@ -7,9 +7,11 @@ jr	init	; 2 bytes
 ; *** JUMP TABLE ***
 jp	strncmp
 jp	addDE
+jp	addHL
 jp	upcase
 jp	unsetZ
 jp	intoDE
+jp	findchar
 
 init:
 	di

tools/emul/zasm_user.asm

@@ -1,9 +1,13 @@
 ; *** JUMP TABLE ***
 JUMP_STRNCMP    .equ    0x02
 JUMP_ADDDE      .equ    0x05
-JUMP_UPCASE     .equ    0x08
-JUMP_UNSETZ     .equ    0x0b
-JUMP_INTODE     .equ    0x0e
+JUMP_ADDHL      .equ    0x08
+JUMP_UPCASE     .equ    0x0b
+JUMP_UNSETZ     .equ    0x0e
+JUMP_INTODE	.equ    0x11
+JUMP_FINDCHAR	.equ    0x14
 
-.org 0x4000
+.equ	USER_CODE	0x4000
+.equ	RAMSTART	0x6000
+.org	USER_CODE
 #include "main.asm"