130 lines
1.8 KiB
ArmAsm
130 lines
1.8 KiB
ArmAsm
GBASL = $26
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GBASH = $27
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HGRPAGE = $E6
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LINE = $FD
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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 $C05E ; set double hires
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sta $C00D ; 80 column
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sta $C001 ; 80 store
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lsr HGRPAGE ; set to $20 (HGR2 set this to $40)
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sta YPOS
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;forever_loop:
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; jmp forever_loop
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draw_raster:
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line_loop:
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lda #7 ; want 8 lines
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sta LINE
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lda YPOS ; check bounds
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bmi go_neg ; if >128, flip to go up
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cmp #64 ; if < 64, flip to go down
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bcs do_add ; otherwise, nothing
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go_pos:
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ldx #$1
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.byte $2C ; bit trick
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go_neg:
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ldx #$ff
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stx smc+1
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do_add:
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clc ; move the bar
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smc:
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adc #1
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sta YPOS
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color_loop: ; get right color
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lda LINE ;(2)
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cmp #$4 ;(2)
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bcc none ;(2)
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eor #$3 ; 00 01 10 11 00 01 10 11
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none: ; 11 10 01 00
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and #$3 ;(2)
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; ldx LINE
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; lda order,X
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clc
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color_smc:
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adc #0
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tax
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lda colors,X
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sta COLOR
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lda YPOS
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sec
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sbc LINE
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; jsr draw_line_color
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; inline!
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;=====================================
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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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;====================================
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; rts
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dec LINE
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bmi line_loop
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bpl color_loop
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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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;
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; x-4 = fc fd fe ff 0 1 2 3
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; lda LINE (2)
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; cmp #$4 (2)
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; bcc none (2)
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; eor #$3 00 01 10 11 00 01 10 11
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;none: 11 10 01 00
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; and #$3 (2)
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;order:
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; .byte 0,1,2,3,3,2,1,0
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colors:
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.byte $00,$11,$22,$33 ; red
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; .byte $00,$11,$22,$33,$33,$22,$11,$00 ; red
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; .byte $00,$DD,$EE,$FF,$FF,$EE,$DD,$00 ; aqua lblue white
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; .byte $00,$AA,$BB,$CC,$CC,$BB,$AA,$00 ; grey yellow mblue
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; .byte $00,$77,$88,$99,$99,$88,$77,$00 ; ugly green
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; .byte $00,$44,$55,$66,$66,$55,$44,$00 ; purple
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