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https://github.com/safiire/n65.git
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83 lines
1.2 KiB
NASM
83 lines
1.2 KiB
NASM
; Create an iNES header
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.ines {"prog": 2, "char": 0, "mapper": 0, "mirror": 1}
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; The supermario.nsf file is 17084 bytes, this includes a 0x80 byte header.
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; It is supposed to be loaded into memory 0x8000, but we don't want that
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; header, so let's include the nsf to 0x8000 - 0x80 so it lines up properly
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.org $7F80
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.incbin "super_mario.nsf"
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; Had to start this prog segment a bit later because the mario nsf is > 16KB
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.org $C300
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start:
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CLD
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SEI
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LDA #$00
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STA $2000
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; Wait for 2 vblanks
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wait_vb1:
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LDA $2002
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BPL wait_vb1
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wait_vb2:
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LDA $2002
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BPL wait_vb2
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; Clear out the sound registers
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LDA #$00
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LDX #$00
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clear_sound_registers:
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STA $4000, X
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INX
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CPX #$0F
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BNE clear_sound_registers
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LDA #$10
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STA $4010
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LDA #$00
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STA $4011
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STA $4012
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STA $4013
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; Enable sound channels (except DMC)
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LDA #$0F
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STA $4015
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; Reset frame counter and clock divider
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LDA #$C0
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STA $4017
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; Set song and NTSC
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LDA #$00 ; Song 0
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LDX #$00 ; NTSC
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JSR $8000
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; Enable Vblank NMI
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LDA #$80
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STA $2000
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forever:
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JMP forever
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nmi:
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LDA $2002
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LDA #$00
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STA $2000
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LDA $80
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STA $2000
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JSR $8000
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RTI
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irq:
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RTI
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.ascii "The end of prog2"
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.org $FFFA
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.dw nmi
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.dw start
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.dw irq
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