A83: pixeltest
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A83: pixeltest
Hi.. its me again.
who wanted a pixeltester?
I modified my pixelplotter.. you remember that? its in ASMGuru...
I have no idea if this will even compile... It uses selfmodifying code..
then it was almost no change needed in the code :)
most of the old is left as comments..
try it please.
it should return Z as the state of the pixel.. (Z=1 pixel set, Z=0 pixel clear)
(no.. I didnt even care to change the name...)
//Olle
;+-----+-----------------------------------------------------------------------+
;| ALH | > PIX < Test a pixel in Graph Backup ³ a=x e=y |
;+-----+-----------------------------------------------------------------------+
;/-----------| PIX |-----------------------------------------------------------\
PIX
; push af ; Uncomment these to save regs..
; push de
ld d,0 ; Do y*12
sla e
sla e
ld hl,0
add hl,de
add hl,de
add hl,de
ld d,0 ; Do x/8
ld e,a
srl e
srl e
srl e
add hl,de
ld de,8e29h
add hl,de ; Add address to graphbuf
ld de,0007h ; Get the remainder of x/8
and e
ld e,a
ld IX,pixtable ; Look up in table witch pixel to be set
add IX,de
ld a,(IX+0) ; and load this
ld (bittst),a
bittst .db $00,$CB
; or (HL) ; xor to toggle pixel, and to clear
; ld (HL),a
; pop de
; pop af
ret
pixtable
.db $7e
.db $76
.db $6e
.db $66
.db $5e
.db $56
.db $4e
.db $46
;\-----------| PIX |-----------------------------------------------------------/