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Display like The Matrix movie on a C64 in 6502 assembly
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| *= $c000 ; 49152 | |
| !to "matrix.prg", cbm | |
| !cpu 6502 ; set processor type | |
| JSR main | |
| RTS | |
| _snake_count !byte $05 | |
| _snake_lengths !byte $05, $08, 10, 14, 20 | |
| _snake_xs !byte 03, 10, 20, 30, 34 | |
| _snake_ys !byte 10, 05, 20, 02, 07 | |
| _current_snake !byte $00 | |
| main | |
| JSR setupscreen | |
| JSR randomizeallsnakes | |
| _main_loop | |
| JSR drawallsnakes | |
| JSR moveallsnakes | |
| JMP _main_loop | |
| RTS | |
| moveallsnakes | |
| LDA #$00 | |
| STA _current_snake | |
| _moveallsnakes_loop | |
| LDA _current_snake | |
| CMP _snake_count | |
| BEQ _end_moveallsnakes | |
| LDY _current_snake | |
| LDA _snake_ys, y | |
| CLC | |
| ADC #$01 | |
| STA _snake_ys, y | |
| INC _current_snake | |
| JMP _moveallsnakes_loop | |
| _end_moveallsnakes | |
| RTS | |
| randomizeallsnakes | |
| LDA #$00 | |
| STA _current_snake | |
| _randomizeallsnakes_loop | |
| LDA _current_snake | |
| CMP _snake_count | |
| BEQ _end_randomizeallsnakes | |
| JSR randomizesnake | |
| INC _current_snake | |
| JMP _randomizeallsnakes_loop | |
| _end_randomizeallsnakes | |
| RTS | |
| randomizesnake | |
| LDY _current_snake | |
| JSR GETRAND | |
| LDA RANDOM+1 | |
| ;AND #39 | |
| STA $0400 | |
| STA _snake_xs, y | |
| LDA RANDOM+1 | |
| STA $0403 | |
| AND #24 | |
| STA $0401 | |
| STA _snake_ys, y | |
| RTS | |
| checksnake | |
| LDY _current_snake | |
| LDA #$00 | |
| STA _addscreen_location | |
| LDA #$D8 | |
| STA _addscreen_location+1 | |
| LDA _snake_xs,y | |
| STA _addscreen_x | |
| LDA _snake_ys,y | |
| STA _addscreen_y | |
| JSR addscreen | |
| LDA _addscreen_location | |
| STA _subscreen_location | |
| LDA _addscreen_location+1 | |
| STA _subscreen_location+1 | |
| LDA #$00 | |
| STA _subscreen_x | |
| LDY _current_snake | |
| LDA _snake_lengths,y | |
| CLC | |
| ADC #$01 | |
| STA _subscreen_y | |
| JSR subscreen | |
| LDA _subscreen_location | |
| STA _isvalidscreencolorlocation_location | |
| LDA _subscreen_location+1 | |
| STA _isvalidscreencolorlocation_location+1 | |
| JSR isvalidscreencolorlocation | |
| LDA #$00 | |
| CMP _isvalidscreencolorlocation_result | |
| BEQ _checksnake_end | |
| LDA #$01 | |
| CMP _isvalidscreencolorlocation_result | |
| BEQ _checksnake_end | |
| JSR randomizesnake | |
| LDY _current_snake | |
| LDA #$00 | |
| STA _snake_ys,y | |
| JMP drawsnake | |
| _checksnake_end | |
| RTS | |
| drawallsnakes | |
| LDA #$00 | |
| STA _current_snake | |
| _drawallsnakes_loop | |
| LDA _current_snake | |
| CMP _snake_count | |
| BEQ _end_drawallsnakes | |
| JSR checksnake | |
| JSR drawsnake | |
| INC _current_snake | |
| JMP _drawallsnakes_loop | |
| _end_drawallsnakes | |
| RTS | |
| _temp_location !byte $00, $00 | |
| drawsnake | |
| LDY _current_snake | |
| LDA #$00 | |
| STA _addscreen_location | |
| LDA #$D8 | |
| STA _addscreen_location+1 | |
| LDA _snake_xs,y | |
| STA _addscreen_x | |
| LDA _snake_ys,y | |
| STA _addscreen_y | |
| JSR addscreen | |
| _drawsnake_main | |
| LDA _addscreen_location | |
| STA _pokescreencolorlocation_location | |
| LDA _addscreen_location+1 | |
| STA _pokescreencolorlocation_location+1 | |
| LDA #$01 | |
| STA _pokescreencolorlocation_value | |
| JSR pokescreencolorlocation | |
| LDY _current_snake | |
| LDA _addscreen_location | |
| STA _temp_location | |
| LDA _addscreen_location+1 | |
| STA _temp_location+1 | |
| LDX _snake_lengths, y | |
| _tail | |
| CPX #$00 | |
| BEQ _blacken | |
| LDA _pokescreencolorlocation_location | |
| STA _sub16_param1 | |
| LDA _pokescreencolorlocation_location+1 | |
| STA _sub16_param1+1 | |
| LDA #$28 | |
| STA _sub16_param2 | |
| LDA #$00 | |
| STA _sub16_param2+1 | |
| JSR sub16 | |
| LDA _sub16_result | |
| STA _pokescreencolorlocation_location | |
| LDA _sub16_result+1 | |
| STA _pokescreencolorlocation_location+1 | |
| LDA #$05 | |
| STA _pokescreencolorlocation_value | |
| JSR pokescreencolorlocation | |
| DEX | |
| JMP _tail | |
| _blacken | |
| LDA _pokescreencolorlocation_location | |
| STA _sub16_param1 | |
| LDA _pokescreencolorlocation_location+1 | |
| STA _sub16_param1+1 | |
| LDA #$28 | |
| STA _sub16_param2 | |
| LDA #$00 | |
| STA _sub16_param2+1 | |
| JSR sub16 | |
| LDA _sub16_result | |
| STA _pokescreencolorlocation_location | |
| LDA _sub16_result+1 | |
| STA _pokescreencolorlocation_location+1 | |
| LDA #$00 | |
| STA _pokescreencolorlocation_value | |
| JSR pokescreencolorlocation | |
| RTS | |
| _setupscreen_current_location !byte $00, $04, $00, $D8 ;data | |
| setupscreen | |
| LDX #$00 | |
| STX $0286 | |
| STX $D020 | |
| STX $D021 | |
| LDA _setupscreen_current_location | |
| STA _cmp16_param1 | |
| LDA _setupscreen_current_location+1 | |
| STA _cmp16_param1+1 | |
| LDA #$E8 | |
| STA _cmp16_param2 | |
| LDA #$07 | |
| STA _cmp16_param2+1 | |
| JSR cmp16 | |
| BEQ _end_setupscreen | |
| LDA _setupscreen_current_location | |
| STA _poke_location | |
| LDA _setupscreen_current_location+1 | |
| STA _poke_location+1 | |
| JSR getrandomchar | |
| LDA _getrandomchar_result | |
| STA _poke_value | |
| JSR poke | |
| LDA _setupscreen_current_location+2 | |
| STA _poke_location | |
| LDA _setupscreen_current_location+3 | |
| STA _poke_location+1 | |
| LDA #$00 | |
| STA _poke_value | |
| JSR poke | |
| CLC | |
| LDA _setupscreen_current_location | |
| ADC #$01 | |
| STA _setupscreen_current_location | |
| LDA _setupscreen_current_location+1 | |
| ADC #$00 | |
| STA _setupscreen_current_location+1 | |
| CLC | |
| LDA _setupscreen_current_location+2 | |
| ADC #$01 | |
| STA _setupscreen_current_location+2 | |
| LDA _setupscreen_current_location+3 | |
| ADC #$00 | |
| STA _setupscreen_current_location+3 | |
| JMP setupscreen | |
| _end_setupscreen | |
| RTS | |
| _getrandomchar_result !byte $00 | |
| getrandomchar | |
| JSR GETRAND | |
| LDA RANDOM+1 | |
| STA _getrandomchar_result | |
| RTS | |
| _isvalidscreencolorlocation_location !byte $00, $00 | |
| _isvalidscreencolorlocation_result !byte $00 ; 0 valid, 1 before screen, 2 after | |
| isvalidscreencolorlocation | |
| LDA #$00 | |
| STA _isvalidscreencolorlocation_result | |
| _isvalidscreencolorlocation_checkbefore | |
| LDA _isvalidscreencolorlocation_location | |
| STA _cmp16_param1 | |
| LDA _isvalidscreencolorlocation_location+1 | |
| STA _cmp16_param1+1 | |
| LDA #$00 | |
| STA _cmp16_param2 | |
| LDA #$D8 | |
| STA _cmp16_param2+1 | |
| CLC | |
| JSR cmp16 | |
| BCS _isvalidscreencolorlocation_checkafter | |
| LDA #$01 | |
| STA _isvalidscreencolorlocation_result | |
| RTS | |
| _isvalidscreencolorlocation_checkafter | |
| LDA #$E8 | |
| STA _cmp16_param2 | |
| LDA #$DB | |
| STA _cmp16_param2+1 | |
| CLC | |
| JSR cmp16 | |
| BCC _end_isvalidscreencolorlocation | |
| LDA #$02 | |
| STA _isvalidscreencolorlocation_result | |
| _end_isvalidscreencolorlocation | |
| RTS | |
| _pokescreencolorlocation_location !byte $00, $00 | |
| _pokescreencolorlocation_value !byte $00 | |
| pokescreencolorlocation | |
| LDA _pokescreencolorlocation_location | |
| STA _isvalidscreencolorlocation_location | |
| LDA _pokescreencolorlocation_location+1 | |
| STA _isvalidscreencolorlocation_location+1 | |
| JSR isvalidscreencolorlocation | |
| LDA _isvalidscreencolorlocation_result | |
| CMP #$00 | |
| BNE _end_pokescreencolorlocation | |
| LDA _pokescreencolorlocation_location | |
| STA _poke_location | |
| LDA _pokescreencolorlocation_location+1 | |
| STA _poke_location+1 | |
| LDA _pokescreencolorlocation_value | |
| STA _poke_value | |
| JSR poke | |
| _end_pokescreencolorlocation | |
| RTS | |
| _peek_location !byte $00, $00 | |
| _peek_result !byte $00 | |
| peek | |
| LDA _peek_location | |
| STA _peek_load+1 | |
| LDA _peek_location+1 | |
| STA _peek_load+2 | |
| _peek_load | |
| LDA $0000 | |
| STA _peek_result | |
| RTS | |
| _poke_location !byte $00, $00 | |
| _poke_value !byte $00 | |
| poke | |
| LDA _poke_location | |
| STA _poke_store+1 | |
| LDA _poke_location+1 | |
| STA _poke_store+2 | |
| LDA _poke_value | |
| _poke_store | |
| STA $0000 | |
| RTS | |
| _add16_param1 !byte $00, $00 | |
| _add16_param2 !byte $00, $00 | |
| _add16_result !byte $00, $00 | |
| add16 | |
| CLC | |
| LDA _add16_param1 | |
| ADC _add16_param2 | |
| STA _add16_result | |
| LDA _add16_param1+1 | |
| ADC _add16_param2+1 | |
| STA _add16_result+1 | |
| RTS | |
| _sub16_param1 !byte $00, $00 | |
| _sub16_param2 !byte $00, $00 | |
| _sub16_result !byte $00, $00 | |
| sub16 | |
| SEC | |
| LDA _sub16_param1+0 | |
| SBC _sub16_param2+0 | |
| STA _sub16_result+0 | |
| LDA _sub16_param1+1 | |
| SBC _sub16_param2+1 | |
| STA _sub16_result+1 | |
| RTS | |
| _cmp16_param1 !byte $00, $00 | |
| _cmp16_param2 !byte $00, $00 | |
| cmp16 | |
| LDA _cmp16_param1+1 | |
| CMP _cmp16_param2+1 | |
| BNE _end_cmp16 | |
| LDA _cmp16_param1 | |
| CMP _cmp16_param2 | |
| _end_cmp16 | |
| RTS | |
| _addscreen_location !byte $00, $00 | |
| _addscreen_x !byte $00 | |
| _addscreen_y !byte $00 | |
| addscreen | |
| CLC ; Add x | |
| LDA _addscreen_location | |
| ADC _addscreen_x | |
| STA _addscreen_location | |
| LDA _addscreen_location+1 | |
| ADC #$00 | |
| STA _addscreen_location+1 ; Done add x | |
| LDY _addscreen_y | |
| _addscreen_loop | |
| CPY #$00 | |
| BEQ _end_addscreen | |
| LDA _addscreen_location | |
| STA _add16_param1 | |
| LDA _addscreen_location+1 | |
| STA _add16_param1+1 | |
| LDA #$28 | |
| STA _add16_param2 | |
| LDA #$00 | |
| STA _add16_param2+1 | |
| JSR add16 | |
| LDA _add16_result | |
| STA _addscreen_location | |
| LDA _add16_result+1 | |
| STA _addscreen_location+1 | |
| CLC | |
| DEY | |
| JMP _addscreen_loop | |
| _end_addscreen | |
| RTS | |
| _subscreen_location !byte $00, $00 | |
| _subscreen_x !byte $00 | |
| _subscreen_y !byte $00 | |
| subscreen | |
| SEC ; sub x | |
| LDA _subscreen_location | |
| SBC _subscreen_x | |
| STA _subscreen_location | |
| LDA _subscreen_location+1 | |
| SBC #$00 | |
| STA _subscreen_location+1 ; Done sub x | |
| LDY _subscreen_y | |
| _subscreen_loop | |
| CPY #$00 | |
| BEQ _end_subscreen | |
| LDA _subscreen_location | |
| STA _sub16_param1 | |
| LDA _subscreen_location+1 | |
| STA _sub16_param1+1 | |
| LDA #$28 | |
| STA _sub16_param2 | |
| LDA #$00 | |
| STA _sub16_param2+1 | |
| JSR sub16 | |
| LDA _sub16_result | |
| STA _subscreen_location | |
| LDA _sub16_result+1 | |
| STA _subscreen_location+1 | |
| CLC | |
| DEY | |
| JMP _subscreen_loop | |
| _end_subscreen | |
| RTS | |
| ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; | |
| ; From http://www.ffd2.com/fridge/math/rand1.s | |
| RANDOM !byte 0,0 | |
| TEMP1 !byte 0,0 | |
| GETRAND | |
| LDA RANDOM+1 | |
| STA TEMP1 | |
| LDA RANDOM | |
| ASL | |
| ROL TEMP1 | |
| ASL | |
| ROL TEMP1 | |
| CLC | |
| ADC RANDOM | |
| PHA | |
| LDA TEMP1 | |
| ADC RANDOM+1 | |
| STA RANDOM+1 | |
| PLA | |
| ADC #$11 | |
| STA RANDOM | |
| LDA RANDOM+1 | |
| ADC #$36 | |
| STA RANDOM+1 | |
| RTS | |
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