From a7538473e43ff10d349a1d1f28886a6a07fb1f48 Mon Sep 17 00:00:00 2001 From: Virgil Dupras Date: Wed, 17 Apr 2019 08:23:01 -0400 Subject: [PATCH] zasm: add support for variable arguments --- apps/zasm/zasm.asm | 266 ++++++++++++++++++++++++++++++++++++++++++++--------- 1 file changed, 223 insertions(+), 43 deletions(-) diff --git a/apps/zasm/zasm.asm b/apps/zasm/zasm.asm index a9b6551..e1b03f4 100644 --- a/apps/zasm/zasm.asm +++ b/apps/zasm/zasm.asm @@ -1,9 +1,14 @@ #include "user.inc" ; *** Consts *** +; Number of rows in the "single" argspec string ARGSPEC_SINGLE_CNT .equ 7 +; Number of rows in the argspec table ARGSPEC_TBL_CNT .equ 12 -INSTR_TBL_PRIMARYC_CNT .equ 25 +; Number of rows in the primary instructions table +INSTR_TBLP_CNT .equ 30 +; size in bytes of each row in the primary instructions table +INSTR_TBLP_ROWSIZE .equ 8 ; *** Code *** .org USER_CODE @@ -12,6 +17,24 @@ ld b, 0 ld c, a ; written bytes ret +unsetZ: + push bc + ld b, a + inc b + cp b + pop bc + ret + +; run RLA the number of times specified in B +rlaX: + ; first, see if B == 0 to see if we need to bail out + dec b + ret c ; C flag means we went negative. nothing to do + inc b +.loop: rla + djnz .loop + ret + ; Sets Z is A is ';', CR, LF, or null. isLineEnd: cp ';' @@ -95,7 +118,7 @@ readArg: call readWord push hl ld hl, tmpVal - call matchArg + call parseArg pop hl pop de ld (de), a @@ -144,9 +167,10 @@ strlen: ret ; find argspec for string at (HL). Returns matching argspec in A. -; Return value 1 holds a special meaning: arg is not empty, but doesn't match -; any argspec (A == 0 means arg is empty). A return value of 1 means an error. -matchArg: +; 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 +; error. +parseArg: call strlen cp 0 ret z ; empty string? A already has our result: 0 @@ -174,7 +198,7 @@ matchArg: djnz .loop1 ; exhausted? we have a problem os specifying a wrong argspec. This is ; an internal consistency error. - ld a, 1 + ld a, 0xff jr .end .found: ; found the matching argspec row. Our result is one byte left of DE. @@ -194,7 +218,7 @@ matchArg: jr .loop2 .loop2notfound: ; something's wrong. error - ld a, 1 + ld a, 0xff jr .end .end: @@ -203,6 +227,83 @@ matchArg: pop bc ret +; Returns, with Z, whether A is a groupId +isGroupId: + cp 0xc ; max group id + 1 + jr nc, .notgroup ; >= 0xc? not a group + cp 0 + jr z, .notgroup ; 0? not supposed to happen. something's wrong. + ; A is a group. ensure Z is set + cp a + ret +.notgroup: + call unsetZ + ret + +; Find argspec A in group id H. +; Set Z according to whether we found the argspec +; If found, the value in A is the argspec value in the group (it's index). +findInGroup: + push bc + push hl + cp 0 ; is our arg empty? If yes, we have nothing to do + jr z, .notfound + + push de + ld de, argGrpTbl + ; group ids start at 1. decrease it, then multiply by two to have a + ; proper offset in argGrpTbl + dec h + push af + ld a, h + add a, a + call JUMP_ADDDE ; At this point, DE points to our group + pop af + ex hl, de + pop de + + ld bc, 4 +.loop: + cpi + jr z, .found + jp po, .notfound + jr .loop +.found: + ; we found our result! Now, what we want to put in A is the index of + ; the found argspec. We have this in C (4 - C + 1). The +1 is because + ; cpi always decreases BC, whether we match or not. + ld a, 3 ; 4 - 1 + sub c + cp a ; ensure Z is set + jr .end +.notfound: + call unsetZ +.end: + pop hl + pop bc + ret + +; Compare argspec from instruction table in A with argument in (HL). +; For constant args, it's easy: if A == (HL), it's a success. +; If A is a group ID, we do something else: we check that (HL) exists in the +; groupspec (argGrpTbl) +matchArg: + cp a, (hl) + ret z + ; A bit of a delicate situation here: we want A to go in H but also + ; (HL) to go in A. If not careful, we overwrite each other. EXX is + ; necessary to avoid invoving other registers. + push hl + exx + ld h, a + push hl + exx + ld a, (hl) + pop hl + call findInGroup + pop hl + ret + ; Compare primary row at (DE) with string at curWord. Sets Z flag if there's a ; match, reset if not. matchPrimaryRow: @@ -215,11 +316,13 @@ matchPrimaryRow: ; name matches, let's see the rest ld ixh, d ld ixl, e - ld a, (curArg1) - cp (ix+4) + ld hl, curArg1 + ld a, (ix+4) + call matchArg jr nz, .end - ld a, (curArg2) - cp (ix+5) + ld hl, curArg2 + ld a, (ix+5) + call matchArg .end: pop ix pop hl @@ -230,13 +333,13 @@ matchPrimaryRow: parseLine: call readLine push de - ld de, instrTBlPrimaryC - ld b, INSTR_TBL_PRIMARYC_CNT + ld de, instrTBlPrimary + ld b, INSTR_TBLP_CNT .loop: ld a, (de) call matchPrimaryRow jr z, .match - ld a, 7 + ld a, INSTR_TBLP_ROWSIZE call JUMP_ADDDE djnz .loop ; no match @@ -244,9 +347,46 @@ parseLine: pop de ret .match: - ld a, 6 ; upcode is on 7th byte - call JUMP_ADDDE - ld a, (de) + ; We have our matching instruction row. We're getting pretty near our + ; goal here! + ; First, let's go in IX mode. It's easier to deal with offsets here. + push ix + ld ixh, d + ld ixl, e + ; First, let's see if we're dealing with a group here + ld a, (ix+4) ; first argspec + call isGroupId + jr nz, .notgroup + ; A is a group, good, now let's get its value + push hl + ld h, a + ld a, (curArg1) + call findInGroup ; we don't check for match, it's supposed to + ; always match. Something is very wrong if it + ; doesn't + ; Now, we have our arg "group value" in A. Were going to need to + ; displace it left by the number of steps specified in the table. + push bc + push af + ld a, (ix+6) ; displacement bit + ld b, a + pop af + call rlaX + pop bc + + ; 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 .end +.notgroup: + ; not a group? easy as pie: we return the opcode directly. + ld a, (ix+7) ; upcode is on 8th byte +.end: + ; At the end, we have our final opcode in A! + pop ix pop de ld (de), a ld a, 1 @@ -256,6 +396,10 @@ parseLine: ; char mnemonic that is called "argspec". This is the table of correspondance. ; Single letters are represented by themselves, so we don't need as much ; metadata. +; Special meaning: +; 0 : no arg +; 1-10 : group id (see Groups section) +; 0xff: error argspecsSingle: .db "ABCDEHL" @@ -274,6 +418,35 @@ argspecTbl: .db 'y', "(IY)" .db 's', "SP", 0, 0 .db 'p', "(SP)" +; we also need argspecs for the condition flags + .db 'Z', "Z", 0, 0, 0 + .db 'z', "NZ", 0, 0 + .db '^', "C", 0, 0, 0 + .db '=', "NC", 0, 0 + .db '+', "P", 0, 0, 0 + .db '-', "M", 0, 0, 0 + .db '1', "PO", 0, 0 + .db '2', "PE", 0, 0 + +; argspecs not in the list: +; N -> NN +; n -> (NN) + +; Groups +; Groups are specified by strings of argspecs. To facilitate jumping to them, +; we have a fixed-sized table. Because most of them are 2 or 4 bytes long, we +; have a table that is 4 in size to minimize consumed space. We treat the two +; groups that take 8 bytes in a special way. +; +; The table below is in order, starting with group 0x01 +argGrpTbl: + .db "bdha" ; 0x01 + .db "Zz^=" ; 0x02 + +argGrpCC: + .db "Zz^=+-12" ; 0xa +argGrpABCDEHL: + .db "BCDEHL_A" ; 0xb ; This is a list of primary instructions (single upcode) that lead to a ; constant (no group code to insert). Format: @@ -281,33 +454,40 @@ argspecTbl: ; 4 bytes for the name (fill with zero) ; 1 byte for arg constant ; 1 byte for 2nd arg constant +; 1 byte displacement for group arguments ; 1 byte for upcode -instrTBlPrimaryC: - .db "ADD", 0, 'A', 'h', 0x86 ; ADD A, HL - .db "CCF", 0, 0, 0, 0x3f ; CCF - .db "CPL", 0, 0, 0, 0x2f ; CPL - .db "DAA", 0, 0, 0, 0x27 ; DAA - .db "DI",0,0, 0, 0, 0xf3 ; DI - .db "EI",0,0, 0, 0, 0xfb ; EI - .db "EX",0,0, 'p', 'h', 0xe3 ; EX (SP), HL - .db "EX",0,0, 'a', 'f', 0x08 ; EX AF, AF' - .db "EX",0,0, 'd', 'h', 0xeb ; EX DE, HL - .db "EXX", 0, 0, 0, 0xd9 ; EXX - .db "HALT", 0, 0, 0x76 ; HALT - .db "INC", 0, 'l', 0, 0x34 ; INC (HL) - .db "JP",0,0, 'l', 0, 0xe9 ; JP (HL) - .db "LD",0,0, 'c', 'A', 0x02 ; LD (BC), A - .db "LD",0,0, 'e', 'A', 0x12 ; LD (DE), A - .db "LD",0,0, 'A', 'c', 0x0a ; LD A, (BC) - .db "LD",0,0, 'A', 'e', 0x0a ; LD A, (DE) - .db "LD",0,0, 's', 'h', 0x0a ; LD SP, HL - .db "NOP", 0, 0, 0, 0x00 ; NOP - .db "RET", 0, 0, 0, 0xc9 ; RET - .db "RLA", 0, 0, 0, 0x17 ; RLA - .db "RLCA", 0, 0, 0x07 ; RLCA - .db "RRA", 0, 0, 0, 0x1f ; RRA - .db "RRCA", 0, 0, 0x0f ; RRCA - .db "SCF", 0, 0, 0, 0x37 ; SCF +instrTBlPrimary: + .db "ADD", 0, 'A', 'h', 0, 0x86 ; ADD A, HL + .db "AND", 0, 'l', 0, 0, 0xa6 ; AND (HL) + .db "AND", 0, 0xa, 0, 0, 0b10100000 ; AND r + .db "CCF", 0, 0, 0, 0, 0x3f ; CCF + .db "CPL", 0, 0, 0, 0, 0x2f ; CPL + .db "DAA", 0, 0, 0, 0, 0x27 ; DAA + .db "DI",0,0, 0, 0, 0, 0xf3 ; DI + .db "EI",0,0, 0, 0, 0, 0xfb ; EI + .db "EX",0,0, 'p', 'h', 0, 0xe3 ; EX (SP), HL + .db "EX",0,0, 'a', 'f', 0, 0x08 ; EX AF, AF' + .db "EX",0,0, 'd', 'h', 0, 0xeb ; EX DE, HL + .db "EXX", 0, 0, 0, 0, 0xd9 ; EXX + .db "HALT", 0, 0, 0, 0x76 ; HALT + .db "INC", 0, 'l', 0, 0, 0x34 ; INC (HL) + .db "JP",0,0, 'l', 0, 0, 0xe9 ; JP (HL) + .db "LD",0,0, 'c', 'A', 0, 0x02 ; LD (BC), A + .db "LD",0,0, 'e', 'A', 0, 0x12 ; LD (DE), A + .db "LD",0,0, 'A', 'c', 0, 0x0a ; LD A, (BC) + .db "LD",0,0, 'A', 'e', 0, 0x0a ; LD A, (DE) + .db "LD",0,0, 's', 'h', 0, 0x0a ; LD SP, HL + .db "NOP", 0, 0, 0, 0, 0x00 ; NOP + .db "OR",0,0, 'l', 0, 0, 0xb6 ; OR (HL) + .db "POP", 0, 0x1, 0, 4, 0b11000001 ; POP qq + .db "RET", 0, 0, 0, 0, 0xc9 ; RET + .db "RET", 0, 0xb, 0, 3, 0b11000000 ; RET cc + .db "RLA", 0, 0, 0, 0, 0x17 ; RLA + .db "RLCA", 0, 0, 0, 0x07 ; RLCA + .db "RRA", 0, 0, 0, 0, 0x1f ; RRA + .db "RRCA", 0, 0, 0, 0x0f ; RRCA + .db "SCF", 0, 0, 0, 0, 0x37 ; SCF + ; *** Variables *** ; enough space for 4 chars and a null