263 lines
8.1 KiB
NASM
263 lines
8.1 KiB
NASM
.inesprg 1 ; 1x 16KB PRG code
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.ineschr 1 ; 1x 8KB CHR data
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.inesmap 0 ; mapper 0 = NROM, no bank swapping
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.inesmir 1 ; background mirroring
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;;;;;;;;;;;;;;;
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.bank 0
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.org $C000
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RESET:
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SEI ; disable IRQs
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CLD ; disable decimal mode
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LDX #$40
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STX $4017 ; disable APU frame IRQ
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LDX #$FF
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TXS ; Set up stack
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INX ; now X = 0
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STX $2000 ; disable NMI
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STX $2001 ; disable rendering
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STX $4010 ; disable DMC IRQs
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vblankwait1: ; First wait for vblank to make sure PPU is ready
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BIT $2002
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BPL vblankwait1
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clrmem:
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LDA #$00
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STA $0000, x
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STA $0100, x
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STA $0200, x
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STA $0400, x
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STA $0500, x
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STA $0600, x
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STA $0700, x
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LDA #$FE
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STA $0300, x
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INX
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BNE clrmem
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vblankwait2: ; Second wait for vblank, PPU is ready after this
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BIT $2002
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BPL vblankwait2
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LoadPalettes:
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LDA $2002 ; read PPU status to reset the high/low latch
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LDA #$3F
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STA $2006 ; write the high byte of $3F00 address
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LDA #$00
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STA $2006 ; write the low byte of $3F00 address
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LDX #$00 ; start out at 0
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LoadPalettesLoop:
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LDA palette, x ; load data from address (palette + the value in x)
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; 1st time through loop it will load palette+0
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; 2nd time through loop it will load palette+1
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; 3rd time through loop it will load palette+2
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; etc
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STA $2007 ; write to PPU
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INX ; X = X + 1
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CPX #$20 ; Compare X to hex $10, decimal 16 - copying 16 bytes = 4 sprites
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BNE LoadPalettesLoop ; Branch to LoadPalettesLoop if compare was Not Equal to zero
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; if compare was equal to 32, keep going down
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LoadSprites:
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LDX #$00 ; start at 0
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LoadSpritesLoop:
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LDA sprites, x ; load data from address (sprites + x)
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STA $0200, x ; store into RAM address ($0200 + x)
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INX ; X = X + 1
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CPX #$20 ; Compare X to hex $20, decimal 32
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BNE LoadSpritesLoop ; Branch to LoadSpritesLoop if compare was Not Equal to zero
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; if compare was equal to 32, keep going down
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LDA #%10000000 ; enable NMI, sprites from Pattern Table 1
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STA $2000
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LDA #%00010000 ; enable sprites
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STA $2001
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Forever:
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JMP Forever ;jump back to Forever, infinite loop
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NMI:
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LDA #$00
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STA $2003 ; set the low byte (00) of the RAM address
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LDA #$02
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STA $4014 ; set the high byte (02) of the RAM address, start the transfer
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LatchController:
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LDA #$01
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STA $4016
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LDA #$00
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STA $4016 ; tell both the controllers to latch buttons
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SkipSeveralButtons:
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; discard input from buttons A, B, Select and Start
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LDA $4016
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LDA $4016
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LDA $4016
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LDA $4016
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; LoadSpritesLoop:
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; LDA sprites, x ; load data from address (sprites + x)
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; STA $0200, x ; store into RAM address ($0200 + x)
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; INX ; X = X + 1
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; CPX #$20 ; Compare X to hex $20, decimal 32
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; BNE LoadSpritesLoop ; Branch to LoadSpritesLoop if compare was Not Equal to zero
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; ; if compare was equal to 32, keep going down
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ReadUp:
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LDA $4016 ; player 1 - Up
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AND #%00000001 ; only look at bit 0
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BEQ ReadUpDone ; branch to ReadBDone if button is NOT pressed (0)
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; add instructions here to do something when button IS pressed (1)
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LDX #0200
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MoveSpritesLoop:
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TXA ; load sprite Y position
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SEC ; make sure carry flag is set
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SBC #$01 ; A = A - 1
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SBC #$01 ; A = A - 1
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STA ; save sprite Y position
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INX
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INX
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INX
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INX
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CPX #$10
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BNE MoveSpritesLoop
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ReadUpDone: ; handling this button is done
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ReadDown:
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LDA $4016 ; player 1 - Down
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AND #%00000001 ; only look at bit 0
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BEQ ReadDownDone ; branch to ReadBDone if button is NOT pressed (0)
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; add instructions here to do something when button IS pressed (1)
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LDA $0200 ; load sprite Y position
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CLC
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ADC #$01 ; A = A - 1
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ADC #$01 ; A = A - 1
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STA $0200 ; save sprite Y position
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LDA $0204 ; load sprite Y position
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CLC
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ADC #$01 ; A = A + 1
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ADC #$01 ; A = A - 1
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STA $0204 ; save sprite Y position
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LDA $0208 ; load sprite Y position
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CLC
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ADC #$01 ; A = A - 1
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ADC #$01 ; A = A - 1
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STA $0208 ; save sprite Y position
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LDA $020C ; load sprite Y position
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CLC
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ADC #$01 ; A = A - 1
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ADC #$01 ; A = A - 1
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STA $020C ; save sprite Y position
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ReadDownDone: ; handling this button is done
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ReadLeft:
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LDA $4016 ; player 1 - Right
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AND #%00000001 ; only look at bit 0
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BEQ ReadLeftDone ; branch to ReadBDone if button is NOT pressed (0)
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; add instructions here to do something when button IS pressed (1)
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LDA $0203 ; load sprite X position
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SEC ; make sure carry flag is set
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SBC #$01 ; A = A - 1
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SBC #$01 ; A = A - 1
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STA $0203 ; save sprite X position
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LDA $0207 ; load sprite X position
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SEC ; make sure the carry flag is set
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SBC #$01 ; A = A + 1
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SBC #$01 ; A = A - 1
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STA $0207 ; save sprite X position
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LDA $020B ; load sprite X position
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SEC ; make sure the carry flag is set
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SBC #$01 ; A = A + 1
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SBC #$01 ; A = A - 1
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STA $020B ; save sprite X position
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LDA $020F ; load sprite X position
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SEC ; make sure the carry flag is set
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SBC #$01 ; A = A + 1
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SBC #$01 ; A = A - 1
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STA $020F ; save sprite X position
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ReadLeftDone: ; handling this button is done
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ReadRight:
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LDA $4016 ; player 1 - Left
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AND #%00000001 ; only look at bit 0
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BEQ ReadRightDone ; branch to ReadADone if button is NOT pressed (0)
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; add instructions here to do something when button IS pressed (1)
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LDA $0203 ; load sprite X position
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CLC ; make sure the carry flag is clear
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ADC #$01 ; A = A + 1
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ADC #$01 ; A = A + 1
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STA $0203 ; save sprite X position
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LDA $0207 ; load sprite X position
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CLC ; make sure the carry flag is clear
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ADC #$01 ; A = A + 1
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ADC #$01 ; A = A + 1
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STA $0207 ; save sprite X position
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LDA $020B ; load sprite X position
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CLC ; make sure the carry flag is clear
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ADC #$01 ; A = A + 1
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ADC #$01 ; A = A + 1
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STA $020B ; save sprite X position
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LDA $020F ; load sprite X position
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CLC ; make sure the carry flag is clear
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ADC #$01 ; A = A + 1
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ADC #$01 ; A = A + 1
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STA $020F ; save sprite X position
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ReadRightDone: ; handling this button is done
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RTI ; return from interrupt
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;;;;;;;;;;;;;;
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.bank 1
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.org $E000
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palette:
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.db $0F,$31,$32,$33,$34,$35,$36,$37,$38,$39,$3A,$3B,$3C,$3D,$3E,$0F
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.db $0F,$1C,$15,$14,$31,$02,$38,$3C,$0F,$1C,$15,$14,$31,$02,$38,$3C
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mario_sprite_addresses_vert:
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.db $00,$04,$08,$0C
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mario_sprite_addresses_horiz:
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.db $03,$07,$0B,$0F
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sprites:
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;vert tile attr horiz
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.db $80, $32, $00, $80 ;sprite 0
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.db $80, $33, $00, $88 ;sprite 1
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.db $88, $34, $00, $80 ;sprite 2
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.db $88, $35, $00, $88 ;sprite 3
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.org $FFFA ;first of the three vectors starts here
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.dw NMI ;when an NMI happens (once per frame if enabled) the
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;processor will jump to the label NMI:
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.dw RESET ;when the processor first turns on or is reset, it will jump
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;to the label RESET:
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.dw 0 ;external interrupt IRQ is not used in this tutorial
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;;;;;;;;;;;;;;
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.bank 2
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.org $0000
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.incbin "mario.chr" ;includes 8KB graphics file from SMB1
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