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zasm: a bit of refactoring

This commit is contained in:
Virgil Dupras 2019-04-20 20:35:45 -04:00
parent f6dddaa380
commit 70f61ec451

View File

@ -13,6 +13,8 @@ INSTR_TBLP_ROWSIZE .equ 8
call parseLine
ld b, 0
ld c, a ; written bytes
ld hl, curUpcode
call copy
ret
unsetZ:
@ -33,6 +35,17 @@ rlaX:
djnz .loop
ret
; Copy BC bytes from (HL) to (DE).
copy:
push bc
push de
push hl
ldir
pop hl
pop de
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.
@ -480,45 +493,17 @@ matchPrimaryRow:
pop hl
ret
; Parse line at (HL) and write resulting opcode(s) in (DE). Returns the number
; of bytes written in A.
;
; Overwrites IX
parseLine:
call readLine
; Check whether we have errors. We don't do any parsing if we do.
ld a, (curArg1)
cp 0xff
jr z, .error
ret z
ld a, (curArg2)
cp 0xff
jr nz, .noerror
.error:
ld a, 0
ret
.noerror:
; Compute the upcode for argspec row at (DE) and arguments in curArg{1,2} and
; writes the resulting upcode in curUpcode. A is the number if bytes written
; to curUpcode (can be zero if something went wrong).
getUpcode:
push ix
push de
ld de, instrTBlPrimary
ld b, INSTR_TBLP_CNT
.loop:
ld a, (de)
call matchPrimaryRow
jr z, .match
ld a, INSTR_TBLP_ROWSIZE
call JUMP_ADDDE
djnz .loop
; no match
xor a
pop de
ret
.match:
; We have our matching instruction row. We're getting pretty near our
; goal here!
push hl
; First, let's go in IX mode. It's easier to deal with offsets here.
ld ixh, d
ld ixl, e
; First, let's see if we're dealing with a group here
; now, let's see if we're dealing with a group here
ld a, (ix+4) ; first argspec
call isGroupId
jr z, .firstArgIsGroup
@ -534,7 +519,6 @@ parseLine:
.isGroup:
; A is a group, good, now let's get its value. DE is pointing to
; the argument.
push hl
ld h, a
ld a, (de)
call findInGroup ; we don't check for match, it's supposed to
@ -554,7 +538,6 @@ parseLine:
; At this point, we have a properly displaced value in A. We'll want
; to OR it with the opcode.
or (ix+7) ; upcode
pop hl
; Success!
jr .writeFirstOpcode
@ -563,14 +546,13 @@ parseLine:
ld a, (ix+7) ; upcode is on 8th byte
.writeFirstOpcode:
; At the end, we have our final opcode in A!
pop de
ld de, curUpcode
ld (de), a
; Good, we are probably finished here for many primary opcodes. However,
; some primary opcodes take 8 or 16 bit constants as an argument and
; if that's the case here, we need to write it too.
; We still have our instruction row in IX. Let's revisit it.
push hl ; we use HL to point to the currently read arg
ld a, (ix+4) ; first argspec
ld hl, curArg1
call checkNOrM
@ -625,6 +607,45 @@ parseLine:
xor a
.end:
pop hl
pop de
pop ix
ret
; Parse line at (HL) and write resulting opcode(s) in curUpcode. Returns the
; number of bytes written in A.
parseLine:
call readLine
; Check whether we have errors. We don't do any parsing if we do.
ld a, (curArg1)
cp 0xff
jr z, .error
ret z
ld a, (curArg2)
cp 0xff
jr nz, .noerror
.error:
xor a
ret
.noerror:
push de
ld de, instrTBlPrimary
ld b, INSTR_TBLP_CNT
.loop:
ld a, (de)
call matchPrimaryRow
jr z, .match
ld a, INSTR_TBLP_ROWSIZE
call JUMP_ADDDE
djnz .loop
; no match
xor a
jr .end
.match:
; We have our matching instruction row. We're getting pretty near our
; goal here!
call getUpcode
.end:
pop de
ret
@ -795,6 +816,9 @@ curArg1:
curArg2:
.db 0, 0, 0
curUpcode:
.db 0, 0, 0, 0
; space for tmp stuff
tmpBuf:
.fill 0x20