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collapseos/apps/zasm/parse.asm
Virgil Dupras f9ae5ca46b zasm: simplify readWord calling
It always reads in the scratchpad with the same max size. No need for
DE-dancing anymore.
2019-05-01 14:19:43 -04:00

129 lines
2.4 KiB
NASM

; *** Consts ***
.equ SCRATCHPAD_SIZE 0x20
; *** Variables ***
scratchpad:
.fill SCRATCHPAD_SIZE
; *** Code ***
; Sets Z is A is ';', CR, LF, or null.
isLineEndOrComment:
cp ';'
ret z
; Continues onto isLineEnd...
; Sets Z is A is CR, LF, or null.
isLineEnd:
or a ; same as cp 0
ret z
cp 0x0d
ret z
cp 0x0a
ret
; Sets Z is A is ' ' '\t' or ','
isSep:
cp ' '
ret z
cp 0x09
ret z
cp ','
ret
; Sets Z is A is ' ', ',', ';', CR, LF, or null.
isSepOrLineEnd:
call isSep
ret z
call isLineEndOrComment
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.
readWord:
push bc
push de
ld de, scratchpad
ld b, SCRATCHPAD_SIZE-1
.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, SCRATCHPAD_SIZE-1
sub a, b
.end:
pop de
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 isLineEndOrComment
jr z, .error
call isSep
jr nz, .success
inc hl
jr .loop
.error:
call JUMP_UNSETZ
ret
.success:
xor a ; ensure Z
ret
; Advance HL to the beginning of the next line, that is, right after the next
; 0x10 or 0x13 or both. If we reach null, we stop and error out.
; Sets Z on success, unsets it on error.
gotoNextLine:
dec hl ; a bit weird, but makes the looping easier
.loop:
inc hl
ld a, (hl)
call isLineEnd
jr nz, .loop
; (HL) is 0x10, 0x13 or 0
or a ; is 0?
jr z, .error
; we might have 0x13 followed by 0x10, let's account for this.
; Yes, 0x10 followed by 0x10 will make us skip two lines, but this is of
; no real consequence in our context.
inc hl
ld a, (hl)
call isLineEnd
jr nz, .success
or a ; is 0?
jr z, .error
; There was another line sep. Skip this char
inc hl
; Continue on to .success
.success:
xor a ; ensure Z
ret
.error:
call JUMP_UNSETZ
ret
; Repeatedly calls gotoNextLine until the line in (HL) points to a line that
; isn't blank or 100% comment. Sets Z if we reach a line, Unset Z if we reach
; EOF
gotoNextNotBlankLine:
call toWord
ret z ; Z set? we have a not-blank line
; Z not set? (HL) is at the end of the line or at the beginning of
; comments.
call gotoNextLine
ret nz
jr gotoNextNotBlankLine