94 lines
1.8 KiB
NASM
94 lines
1.8 KiB
NASM
processor 6502
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multicolor SUBROUTINE
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; Prepare data struct for MultiColor mode
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; ----------------------------------------------------------------------
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multicolorInit:
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; Make font higher half the inverse of lower one
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; TODO: merge these edits with actual font binary
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ldx #$00
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.tggsCopy
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dex
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lda tggsFont,x
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eor #$ff
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sta $2400,x
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lda tggsFont + $100,x
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eor #$ff
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sta $2500,x
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lda tggsFont + $200,x
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eor #$ff
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sta $2600,x
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lda tggsFont + $300,x
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eor #$ff
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sta $2700,x
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cpx #$0
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bne .tggsCopy
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; Alter character definitions in RAM (using previous defined table)
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; TODO: merge these edits with actual font binary
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ldx #$8
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.editLoop:
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dex
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lda .multicolorSnakeTile,x
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sta tggsFont + SNAKE_TILE * 8,x
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lda .multicolorFoodTile,x
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sta tggsFont + FOOD_TILE * 8,x
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; lda .multicolorOtherTile,x
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; sta tggsFont + SOME_TILE * 8,x
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; ...
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cpx #$0
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bne .editLoop
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; Tell VIC-II to use:
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; - screen text memory at $400 = $400 * 1
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; - characters ROM at $2000 = $400 * 8
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lda #$18
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sta $d018
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rts
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; Activate multicolor mode
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; ----------------------------------------------------------------------
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multicolorOn:
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; Set colors
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lda #9
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sta $d021 ; 00 is brown
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lda #2
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sta $d022 ; 01 is red
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lda #13
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sta $d023 ; 10 is green
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; and of course
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; 11 is the colour specified in color RAM
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lda $d016
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ora #$10
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sta $d016
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rts
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; Deactivate multicolor mode
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; ----------------------------------------------------------------------
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multicolorOff:
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lda $d016
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and #$ef
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sta $d016
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rts
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; Costants
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; ----------------------------------------------------------------------
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.multicolorCommodoreTile:
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BYTE #$00,#$30,#$cc,#$ca,#$c0,#$c5,#$cc,#$30
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.multicolorSnakeTile:
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BYTE #$00,#$28,#$ab,#$ab,#$ab,#$ab,#$28,#$00
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.multicolorFoodTile:
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BYTE #%00010101
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BYTE #%10010101
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BYTE #%10010101
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BYTE #%10010101
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BYTE #%10101000
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BYTE #%00100000
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BYTE #%00100000
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BYTE #%10000000
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