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collapseos/apps/zasm/tok.asm

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2019-04-21 23:25:52 +10:00
; tok
;
; Tokenizes an ASM source file into 1, 2 or 3-sized structures.
;
; *** Requirements ***
; JUMP_UPCASE
; *** Code ***
; Parse line in (HL) and place each element in tokInstr, tokArg1, tokArg2. Those
; values are null-terminated and empty if not present. All letters are
; uppercased.
2019-04-21 23:25:52 +10:00
; Sets Z on success, unsets it on error. Blank line is not an error.
; (as of now, we don't have any error condition. We always succeed)
tokenize:
push de
xor a
ld (tokInstr), a
ld (tokArg1), a
ld (tokArg2), a
ld de, tokInstr
ld a, 4
call readWord
call toWord
jr nz, .end
ld de, tokArg1
ld a, 8
call readWord
call toWord
jr nz, .end
ld de, tokArg2
call readWord
.end:
cp a ; ensure Z
pop de
ret
; Sets Z is A is ';', CR, LF, or null.
isLineEnd:
cp ';'
ret z
cp 0
ret z
cp 0x0d
ret z
cp 0x0a
ret
; Sets Z is A is ' ' or ','
isSep:
cp ' '
ret z
cp ','
ret
; Sets Z is A is ' ', ',', ';', CR, LF, or null.
isSepOrLineEnd:
call isSep
ret z
call isLineEnd
ret
; read word in (HL) and put it in (DE), null terminated, for a maximum of A
; characters. As a result, A is the read length. HL is advanced to the next
; separator char.
readWord:
push bc
ld b, a
.loop:
ld a, (hl)
call isSepOrLineEnd
jr z, .success
call JUMP_UPCASE
ld (de), a
inc hl
inc de
djnz .loop
.success:
xor a
ld (de), a
ld a, 4
sub a, b
jr .end
.error:
xor a
ld (de), a
.end:
pop bc
ret
; (HL) being a string, advance it to the next non-sep character.
; Set Z if we could do it before the line ended, reset Z if we couldn't.
toWord:
.loop:
ld a, (hl)
call isLineEnd
jr z, .error
call isSep
jr nz, .success
inc hl
jr .loop
.error:
; we need the Z flag to be unset and it is set now. Let's CP with
; something it can't be equal to, something not a line end.
cp 'a' ; Z flag unset
ret
.success:
; We need the Z flag to be set and it is unset. Let's compare it with
; itself to return a set Z
cp a
ret
; *** Variables ***
tokInstr:
.fill 5
tokArg1:
.fill 9
tokArg2:
.fill 9