dos33fsprogs/dhgr/raster2.s
2020-10-09 01:06:02 -04:00

72 lines
839 B
ArmAsm

GBASL = $26
GBASH = $27
HGRPAGE = $E6
YPOS = $FE
COLOR = $FF
HGR = $F3E2
HGR2 = $F3D8
HPOSN = $F411
raster:
jsr HGR
jsr HGR2
; sta $C050 ; set graphics
; sta $C057 ; set hires
; sta $C052 ; set fullscreen
sta $C05E ; set double hires
sta $C00D ; 80 column
sta $C001 ; 80 store
lda #$20
sta HGRPAGE
outer_loop:
lda #0
sta YPOS
color_loop:
lda #$22
inc COLOR
lda YPOS
jsr draw_line_color
inc YPOS
lda YPOS
cmp #192
bne color_loop
forever:
jmp outer_loop
;=============================
; draw line of color in COLOR
;=============================
draw_line_color:
ldx #0
ldy #0
jsr HPOSN
ldy #39
loop_it:
; set page2
sta $C055
jsr next_pixel
; set page1
sta $C054
jsr next_pixel
dey
bpl loop_it
rts
next_pixel:
lda COLOR ; 2
sta (GBASL),Y ; 3
cmp #$80 ; 2
rol COLOR ; 2
rts ; 1