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cc65/libsrc/c64/soft80_kplot.s
2015-09-28 17:12:20 +02:00

65 lines
1.3 KiB
ArmAsm

.export soft80_kplot
.include "c64.inc"
.include "soft80.inc"
soft80_kplot:
bcs @getpos
stx CURS_Y
sty CURS_X
; calc pointer to bitmap
lda _bitmaplo,x
clc
adc _bitmapxlo,y
sta SCREEN_PTR
lda _bitmaphi,x
adc _bitmapxhi,y
sta SCREEN_PTR+1
; calc pointer to vram
tya
lsr a ; NOTE: we can save 2 cycles here at the expense of
; making the tables twice as big (+50 bytes)
clc
adc _vramlo,x
sta CRAM_PTR
lda #0
adc _vramhi,x
sta CRAM_PTR+1
@getpos:
ldx CURS_Y
ldy CURS_X
rts
.rodata
_bitmapxlo:
.repeat 80,col
.byte <((col/2)*8)
.endrepeat
_bitmapxhi:
.repeat 80,col
.byte >((col/2)*8)
.endrepeat
_vramlo:
.repeat 25,row
.byte <(soft80_vram+(row*40))
.endrepeat
_vramhi:
.repeat 25,row
.byte >(soft80_vram+(row*40))
.endrepeat
_bitmaplo:
.repeat 25,row
.byte <(soft80_bitmap+(row*40*8))
.endrepeat
_bitmaphi:
.repeat 25,row
.byte >(soft80_bitmap+(row*40*8))
.endrepeat