63 lines
1.2 KiB
Plaintext
63 lines
1.2 KiB
Plaintext
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setup_hdma:
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sep #$20 : .as
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rep #$10 : .xl
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stz $420b
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stz $420c
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lda #$02 ;A to B; direct; 2x single reg
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sta $4320 ;we use ch. 2 for color data
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lda #$22 ;2122 = CG RAM
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sta $4321 ;dest: CG RAM
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lda #^hdma_pal
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ldy #!hdma_pal
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sty $4322
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sta $4324
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lda #$00 ;A to B; direct; 1x single reg
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sta $4310 ;ch. 1 for color address
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lda #$21 ;2121 = CG addr
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sta $4311 ;dest: CG Address
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lda #^hdma_cg_addr
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ldy #!hdma_cg_addr
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sty $4312
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sta $4314
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lda #$00 ;A to B; direct; 1x single reg
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sta $4330 ;ch. 3 for mode switch
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lda #$05 ;2105 = BG mode
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sta $4331
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lda #^hdma_mode
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ldy #!hdma_mode
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sty $4332
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sta $4334
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lda #$03 ;A to B; direct; 2x 2x single reg
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sta $4340 ;ch. 4 for scroll
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lda #$0d ;210d = BG1HOFS
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sta $4341
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lda #^hdma_scroll
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ldy #!hdma_scroll
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sty $4342
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sta $4344
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lda #$01 ;A to B; direct; 1x two reg
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sta $4350 ;ch. 5 for color math
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lda #$31 ;2131 + 2132 = math, color constant
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sta $4351
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lda #^hdma_math
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ldy #!hdma_math
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sty $4352
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sta $4354
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lda #$3a
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sta $420c ;enable HDMA ch. 1+3+4+5
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jsr waitblank
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lda #$3e
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sta $420c ;enable HDMA ch. 2 too
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lda #$81 ;VBlank NMI + Auto Joypad Read
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sta $4200 ;enable V-BLANK NMI
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rts
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