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zasm: add support for BIT

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This commit is contained in:
Virgil Dupras 2019-04-21 13:41:55 -04:00
parent e073fbff79
commit e9e2f30fc5
2 changed files with 82 additions and 2 deletions
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3
apps/zasm/tests/geninstrs.py
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@ -126,6 +126,9 @@ def main():
# we don't test the displacements for IX/IY because there can't be
# any.
args1 = args1[:1]
if n == 'BIT':
# we only want to keep 1, 2, 4
args1 = args1[:3]
if args1:
for arg1 in args1:
args2 = genargs(a2)

81
apps/zasm/zasm.asm
View File

@ -4,7 +4,7 @@
; Number of rows in the argspec table
ARGSPEC_TBL_CNT .equ 28
; Number of rows in the primary instructions table
INSTR_TBL_CNT .equ 104
INSTR_TBL_CNT .equ 108
; size in bytes of each row in the primary instructions table
INSTR_TBL_ROWSIZE .equ 9
@ -469,7 +469,6 @@ handleJPIX:
jr handleJPIXY
handleJPIY:
ld a, 0xfd
jr handleJPIXY
handleJPIXY:
ld (curUpcode), a
ld a, (curArg1+1)
@ -484,6 +483,80 @@ handleJPIXY:
xor c
ret
; Handle the first argument of BIT. Sets Z if first argument is valid, unset it
; if there's an error.
handleBIT:
ld a, (curArg1+1)
cp 8
jr nc, .error ; >= 8? error
; We're good
cp a ; ensure Z
ret
.error:
xor c
call unsetZ
ret
handleBITHL:
call handleBIT
ret nz ; error
ld a, 0xcb ; first upcode
ld (curUpcode), a
ld a, (curArg1+1) ; 0-7
ld b, 3 ; displacement
call rlaX
or 0b01000110 ; 2nd upcode
ld (curUpcode+1), a
ld c, 2
ret
handleBITIX:
ld a, 0xdd
jr handleBITIXY
handleBITIY:
ld a, 0xfd
handleBITIXY:
ld (curUpcode), a ; first upcode
call handleBIT
ret nz ; error
ld a, 0xcb ; 2nd upcode
ld (curUpcode+1), a
ld a, (curArg2+1) ; IXY displacement
ld (curUpcode+2), a
ld a, (curArg1+1) ; 0-7
ld b, 3 ; displacement
call rlaX
or 0b01000110 ; 4th upcode
ld (curUpcode+3), a
ld c, 4
ret
handleBITR:
call handleBIT
ret nz ; error
; get group value
ld a, (curArg2)
ld h, 0xb
call findInGroup
push af ; push group value
; write first upcode
ret nz ; error
ld a, 0xcb ; first upcode
ld (curUpcode), a
; get bit value
ld a, (curArg1+1) ; 0-7
ld b, 3 ; displacement
call rlaX
; Now we have group value in stack, bit value in A (properly shifted)
; and we want to OR them together
pop bc ; from push af earlier
or b ; Now we have our ORed value
or 0b01000000 ; and with the constant value for that byte...
; we're good!
ld (curUpcode+1), a
ld c, 2
ret
; 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).
@ -810,6 +883,10 @@ instrTBl:
.db "AND", 0, 'n', 0, 0, 0xe6 , 0 ; AND n
.db "AND", 0, 'x', 0, 0, 0xdd, 0xa6 ; AND (IX+d)
.db "AND", 0, 'y', 0, 0, 0xfd, 0xa6 ; AND (IY+d)
.db "BIT", 0,'n','l',0x20 \ .dw handleBITHL ; BIT b, (HL)
.db "BIT", 0,'n','x',0x20 \ .dw handleBITIX ; BIT b, (IX+d)
.db "BIT", 0,'n','y',0x20 \ .dw handleBITIY ; BIT b, (IY+d)
.db "BIT", 0,'n',0xb,0x20 \ .dw handleBITR ; BIT b, r
.db "CALL", 0xa, 'N', 3, 0b11000100 , 0 ; CALL cc, NN
.db "CALL", 'N', 0, 0, 0xcd , 0 ; CALL NN
.db "CCF", 0, 0, 0, 0, 0x3f , 0 ; CCF