dos33fsprogs/dhgr/raster4.s

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ArmAsm
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GBASL = $26
GBASH = $27
HGRPAGE = $E6
BASE = $FC
LINE = $FD
YPOS = $FE
COLOR = $FF
HGR = $F3E2
HGR2 = $F3D8
HPOSN = $F411
raster:
;=========================
; configure double hires
;=========================
jsr HGR
jsr HGR2
sta $C05E ; set double hires
sta $C00D ; 80 column
sta $C001 ; 80 store
lsr HGRPAGE ; set to $20 (HGR2 set this to $40)
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; ldy #100
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big_loop:
lda #0 ; 2 ; blueline
jsr one_line ; 3
lda #4 ; 2 ; redline
jsr one_line ; 3
tya ; YPOS
bmi go_neg ; if >128, flip to go up
cmp #64 ; if < 64, flip to go down
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bcs smc ; otherwise, nothing
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go_pos:
ldx #$c8
.byte $2C ; bit trick
go_neg:
ldx #$88
stx smc
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smc: ; move the bar
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iny ; c8=iny, 88=dey
bne big_loop ; bra
one_line:
sta BASE ; 2
tya ; 1
eor #$10 ; 2
tay ; 1
; fallthrough
;=======================================
draw_raster:
lda #7 ; want 8 lines
sta LINE
color_loop: ; get right color
lda LINE ;(2)
cmp #$4 ;(2)
bcc none ;(2)
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eor #$3 ; 2 00 01 10 11 00 01 10 11
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none: ; 11 10 01 00
and #$3 ;(2)
clc
color_smc:
adc BASE
tax
lda colors,X
sta COLOR
tya
pha ; save YPOS
; sec ; c always 0
sbc LINE
;=============================
; draw line of color in COLOR
;=============================
draw_line_color:
ldx #0
ldy #0
jsr HPOSN ; put into GBASL addr of coord (Y,X),A
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; ldy #39
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loop_it:
; set page2
sta $C055 ; 3
jsr next_pixel ; 3
; set page1
sta $C054 ; 3
jsr next_pixel ; 3
dey ; 1
bpl loop_it ; 2
pla
tay
;====================================
dec LINE
bpl color_loop
rts
;==============================
;==============================
next_pixel:
lda COLOR ; 2
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sta (GBASL),Y ; 2
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cmp #$80 ; 2
rol COLOR ; 2
rts ; 1
colors:
.byte $00,$11,$22,$33 ; red
.byte $00,$DD,$EE,$FF ; blue/white
; .byte $00,$11,$22,$33,$33,$22,$11,$00 ; red
; .byte $00,$DD,$EE,$FF,$FF,$EE,$DD,$00 ; black aqua lblue white
; .byte $00,$AA,$BB,$CC,$CC,$BB,$AA,$00 ; grey yellow mblue
; .byte $00,$77,$88,$99,$99,$88,$77,$00 ; ugly green
; .byte $00,$44,$55,$66,$66,$55,$44,$00 ; purple