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