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zasm: add support for variable arguments
This commit is contained in:
Virgil Dupras
parent
38e40bfc16
commit
a7538473e4
@ -1,9 +1,14 @@
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#include "user.inc"
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; *** Consts ***
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; Number of rows in the "single" argspec string
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ARGSPEC_SINGLE_CNT .equ 7
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; Number of rows in the argspec table
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ARGSPEC_TBL_CNT .equ 12
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INSTR_TBL_PRIMARYC_CNT .equ 25
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; Number of rows in the primary instructions table
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INSTR_TBLP_CNT .equ 30
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; size in bytes of each row in the primary instructions table
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INSTR_TBLP_ROWSIZE .equ 8
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; *** Code ***
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.org USER_CODE
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@ -12,6 +17,24 @@ ld b, 0
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ld c, a ; written bytes
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ret
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unsetZ:
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push bc
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ld b, a
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inc b
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cp b
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pop bc
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ret
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; run RLA the number of times specified in B
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rlaX:
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; first, see if B == 0 to see if we need to bail out
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dec b
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ret c ; C flag means we went negative. nothing to do
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inc b
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.loop: rla
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djnz .loop
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ret
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; Sets Z is A is ';', CR, LF, or null.
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isLineEnd:
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cp ';'
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@ -95,7 +118,7 @@ readArg:
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call readWord
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push hl
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ld hl, tmpVal
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call matchArg
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call parseArg
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pop hl
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pop de
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ld (de), a
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@ -144,9 +167,10 @@ strlen:
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ret
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; find argspec for string at (HL). Returns matching argspec in A.
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; Return value 1 holds a special meaning: arg is not empty, but doesn't match
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; any argspec (A == 0 means arg is empty). A return value of 1 means an error.
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matchArg:
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; Return value 0xff holds a special meaning: arg is not empty, but doesn't match
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; any argspec (A == 0 means arg is empty). A return value of 0xff means an
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; error.
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parseArg:
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call strlen
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cp 0
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ret z ; empty string? A already has our result: 0
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@ -174,7 +198,7 @@ matchArg:
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djnz .loop1
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; exhausted? we have a problem os specifying a wrong argspec. This is
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; an internal consistency error.
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ld a, 1
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ld a, 0xff
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jr .end
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.found:
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; found the matching argspec row. Our result is one byte left of DE.
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@ -194,7 +218,7 @@ matchArg:
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jr .loop2
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.loop2notfound:
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; something's wrong. error
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ld a, 1
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ld a, 0xff
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jr .end
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.end:
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@ -203,6 +227,83 @@ matchArg:
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pop bc
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ret
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; Returns, with Z, whether A is a groupId
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isGroupId:
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cp 0xc ; max group id + 1
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jr nc, .notgroup ; >= 0xc? not a group
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cp 0
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jr z, .notgroup ; 0? not supposed to happen. something's wrong.
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; A is a group. ensure Z is set
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cp a
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ret
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.notgroup:
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call unsetZ
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ret
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; Find argspec A in group id H.
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; Set Z according to whether we found the argspec
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; If found, the value in A is the argspec value in the group (it's index).
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findInGroup:
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push bc
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push hl
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cp 0 ; is our arg empty? If yes, we have nothing to do
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jr z, .notfound
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push de
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ld de, argGrpTbl
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; group ids start at 1. decrease it, then multiply by two to have a
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; proper offset in argGrpTbl
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dec h
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push af
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ld a, h
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add a, a
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call JUMP_ADDDE ; At this point, DE points to our group
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pop af
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ex hl, de
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pop de
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ld bc, 4
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.loop:
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cpi
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jr z, .found
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jp po, .notfound
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jr .loop
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.found:
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; we found our result! Now, what we want to put in A is the index of
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; the found argspec. We have this in C (4 - C + 1). The +1 is because
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; cpi always decreases BC, whether we match or not.
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ld a, 3 ; 4 - 1
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sub c
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cp a ; ensure Z is set
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jr .end
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.notfound:
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call unsetZ
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.end:
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pop hl
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pop bc
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ret
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; Compare argspec from instruction table in A with argument in (HL).
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; For constant args, it's easy: if A == (HL), it's a success.
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; If A is a group ID, we do something else: we check that (HL) exists in the
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; groupspec (argGrpTbl)
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matchArg:
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cp a, (hl)
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ret z
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; A bit of a delicate situation here: we want A to go in H but also
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; (HL) to go in A. If not careful, we overwrite each other. EXX is
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; necessary to avoid invoving other registers.
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push hl
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exx
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ld h, a
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push hl
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exx
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ld a, (hl)
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pop hl
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call findInGroup
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pop hl
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ret
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; Compare primary row at (DE) with string at curWord. Sets Z flag if there's a
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; match, reset if not.
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matchPrimaryRow:
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@ -215,11 +316,13 @@ matchPrimaryRow:
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; name matches, let's see the rest
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ld ixh, d
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ld ixl, e
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ld a, (curArg1)
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cp (ix+4)
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ld hl, curArg1
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ld a, (ix+4)
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call matchArg
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jr nz, .end
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ld a, (curArg2)
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cp (ix+5)
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ld hl, curArg2
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ld a, (ix+5)
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call matchArg
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.end:
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pop ix
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pop hl
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@ -230,13 +333,13 @@ matchPrimaryRow:
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parseLine:
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call readLine
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push de
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ld de, instrTBlPrimaryC
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ld b, INSTR_TBL_PRIMARYC_CNT
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ld de, instrTBlPrimary
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ld b, INSTR_TBLP_CNT
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.loop:
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ld a, (de)
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call matchPrimaryRow
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jr z, .match
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ld a, 7
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ld a, INSTR_TBLP_ROWSIZE
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call JUMP_ADDDE
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djnz .loop
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; no match
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@ -244,9 +347,46 @@ parseLine:
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pop de
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ret
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.match:
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ld a, 6 ; upcode is on 7th byte
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call JUMP_ADDDE
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ld a, (de)
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; We have our matching instruction row. We're getting pretty near our
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; goal here!
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; First, let's go in IX mode. It's easier to deal with offsets here.
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push ix
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ld ixh, d
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ld ixl, e
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; First, let's see if we're dealing with a group here
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ld a, (ix+4) ; first argspec
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call isGroupId
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jr nz, .notgroup
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; A is a group, good, now let's get its value
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push hl
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ld h, a
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ld a, (curArg1)
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call findInGroup ; we don't check for match, it's supposed to
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; always match. Something is very wrong if it
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; doesn't
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; Now, we have our arg "group value" in A. Were going to need to
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; displace it left by the number of steps specified in the table.
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push bc
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push af
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ld a, (ix+6) ; displacement bit
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ld b, a
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pop af
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call rlaX
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pop bc
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; At this point, we have a properly displaced value in A. We'll want
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; to OR it with the opcode.
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or (ix+7) ; upcode
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pop hl
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; Success!
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jr .end
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.notgroup:
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; not a group? easy as pie: we return the opcode directly.
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ld a, (ix+7) ; upcode is on 8th byte
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.end:
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; At the end, we have our final opcode in A!
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pop ix
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pop de
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ld (de), a
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ld a, 1
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@ -256,6 +396,10 @@ parseLine:
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; char mnemonic that is called "argspec". This is the table of correspondance.
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; Single letters are represented by themselves, so we don't need as much
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; metadata.
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; Special meaning:
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; 0 : no arg
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; 1-10 : group id (see Groups section)
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; 0xff: error
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argspecsSingle:
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.db "ABCDEHL"
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@ -274,6 +418,35 @@ argspecTbl:
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.db 'y', "(IY)"
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.db 's', "SP", 0, 0
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.db 'p', "(SP)"
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; we also need argspecs for the condition flags
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.db 'Z', "Z", 0, 0, 0
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.db 'z', "NZ", 0, 0
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.db '^', "C", 0, 0, 0
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.db '=', "NC", 0, 0
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.db '+', "P", 0, 0, 0
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.db '-', "M", 0, 0, 0
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.db '1', "PO", 0, 0
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.db '2', "PE", 0, 0
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; argspecs not in the list:
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; N -> NN
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; n -> (NN)
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; Groups
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; Groups are specified by strings of argspecs. To facilitate jumping to them,
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; we have a fixed-sized table. Because most of them are 2 or 4 bytes long, we
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; have a table that is 4 in size to minimize consumed space. We treat the two
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; groups that take 8 bytes in a special way.
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;
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; The table below is in order, starting with group 0x01
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argGrpTbl:
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.db "bdha" ; 0x01
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.db "Zz^=" ; 0x02
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argGrpCC:
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.db "Zz^=+-12" ; 0xa
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argGrpABCDEHL:
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.db "BCDEHL_A" ; 0xb
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; This is a list of primary instructions (single upcode) that lead to a
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; constant (no group code to insert). Format:
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@ -281,33 +454,40 @@ argspecTbl:
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; 4 bytes for the name (fill with zero)
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; 1 byte for arg constant
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; 1 byte for 2nd arg constant
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; 1 byte displacement for group arguments
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; 1 byte for upcode
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instrTBlPrimaryC:
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.db "ADD", 0, 'A', 'h', 0x86 ; ADD A, HL
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.db "CCF", 0, 0, 0, 0x3f ; CCF
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.db "CPL", 0, 0, 0, 0x2f ; CPL
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.db "DAA", 0, 0, 0, 0x27 ; DAA
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.db "DI",0,0, 0, 0, 0xf3 ; DI
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.db "EI",0,0, 0, 0, 0xfb ; EI
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.db "EX",0,0, 'p', 'h', 0xe3 ; EX (SP), HL
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.db "EX",0,0, 'a', 'f', 0x08 ; EX AF, AF'
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.db "EX",0,0, 'd', 'h', 0xeb ; EX DE, HL
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.db "EXX", 0, 0, 0, 0xd9 ; EXX
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.db "HALT", 0, 0, 0x76 ; HALT
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.db "INC", 0, 'l', 0, 0x34 ; INC (HL)
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.db "JP",0,0, 'l', 0, 0xe9 ; JP (HL)
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.db "LD",0,0, 'c', 'A', 0x02 ; LD (BC), A
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.db "LD",0,0, 'e', 'A', 0x12 ; LD (DE), A
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.db "LD",0,0, 'A', 'c', 0x0a ; LD A, (BC)
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.db "LD",0,0, 'A', 'e', 0x0a ; LD A, (DE)
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.db "LD",0,0, 's', 'h', 0x0a ; LD SP, HL
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.db "NOP", 0, 0, 0, 0x00 ; NOP
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.db "RET", 0, 0, 0, 0xc9 ; RET
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.db "RLA", 0, 0, 0, 0x17 ; RLA
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.db "RLCA", 0, 0, 0x07 ; RLCA
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.db "RRA", 0, 0, 0, 0x1f ; RRA
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.db "RRCA", 0, 0, 0x0f ; RRCA
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.db "SCF", 0, 0, 0, 0x37 ; SCF
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instrTBlPrimary:
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.db "ADD", 0, 'A', 'h', 0, 0x86 ; ADD A, HL
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.db "AND", 0, 'l', 0, 0, 0xa6 ; AND (HL)
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.db "AND", 0, 0xa, 0, 0, 0b10100000 ; AND r
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.db "CCF", 0, 0, 0, 0, 0x3f ; CCF
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.db "CPL", 0, 0, 0, 0, 0x2f ; CPL
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.db "DAA", 0, 0, 0, 0, 0x27 ; DAA
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.db "DI",0,0, 0, 0, 0, 0xf3 ; DI
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.db "EI",0,0, 0, 0, 0, 0xfb ; EI
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.db "EX",0,0, 'p', 'h', 0, 0xe3 ; EX (SP), HL
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.db "EX",0,0, 'a', 'f', 0, 0x08 ; EX AF, AF'
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.db "EX",0,0, 'd', 'h', 0, 0xeb ; EX DE, HL
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.db "EXX", 0, 0, 0, 0, 0xd9 ; EXX
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.db "HALT", 0, 0, 0, 0x76 ; HALT
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.db "INC", 0, 'l', 0, 0, 0x34 ; INC (HL)
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.db "JP",0,0, 'l', 0, 0, 0xe9 ; JP (HL)
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.db "LD",0,0, 'c', 'A', 0, 0x02 ; LD (BC), A
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.db "LD",0,0, 'e', 'A', 0, 0x12 ; LD (DE), A
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.db "LD",0,0, 'A', 'c', 0, 0x0a ; LD A, (BC)
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.db "LD",0,0, 'A', 'e', 0, 0x0a ; LD A, (DE)
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.db "LD",0,0, 's', 'h', 0, 0x0a ; LD SP, HL
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.db "NOP", 0, 0, 0, 0, 0x00 ; NOP
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.db "OR",0,0, 'l', 0, 0, 0xb6 ; OR (HL)
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.db "POP", 0, 0x1, 0, 4, 0b11000001 ; POP qq
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.db "RET", 0, 0, 0, 0, 0xc9 ; RET
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.db "RET", 0, 0xb, 0, 3, 0b11000000 ; RET cc
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.db "RLA", 0, 0, 0, 0, 0x17 ; RLA
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.db "RLCA", 0, 0, 0, 0x07 ; RLCA
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.db "RRA", 0, 0, 0, 0, 0x1f ; RRA
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.db "RRCA", 0, 0, 0, 0x0f ; RRCA
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.db "SCF", 0, 0, 0, 0, 0x37 ; SCF
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; *** Variables ***
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; enough space for 4 chars and a null
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