mirror of https://github.com/smartykit/apple1.git
96 lines
1.9 KiB
NASM
96 lines
1.9 KiB
NASM
;printing 8x8 picture in the center with '*'
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PIC_WIDTH = 8
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PIC_HEIGHT = 8
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OFFSET_X = (40 - PIC_WIDTH)/2
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PIC_ADDRESS = $1111
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ROW_ADDRESS = PIC_ADDRESS + PIC_HEIGHT
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; Y - row number
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; X - column (pixel) number
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JSR NEXT_ROW
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LDA #$0
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STA ROW_ADDRESS ;initialize row counter with 0
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LDY #PIC_HEIGHT
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ROWS_LOOP: JSR PRINT_OFFSET
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LDA ROW_ADDRESS
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TAX
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LDA PIC_ADDRESS, X
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LDX #PIC_WIDTH
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NEXT_PIXEL: ASL
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BCC NO_PIXEL
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JSR PRINT_STAR
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JMP AFTER_PIXEL
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NO_PIXEL: JSR PRINT_BLANK
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AFTER_PIXEL: DEX
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BNE NEXT_PIXEL
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JSR NEXT_ROW
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INC ROW_ADDRESS
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DEY
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BNE ROWS_LOOP
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JSR NEXT_ROW
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JMP RESET
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;printing offset subroutine (optional: save registers A and X)
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PRINT_OFFSET: PHA ;save A
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TXA ;X->A
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PHA ;save X
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LDX #OFFSET_X
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OFFSET_LOOP: LDA #' '
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JSR ECHO
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DEX
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BNE OFFSET_LOOP
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PLA ;restore X
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TAX ;A->X
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PLA ;restore A
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RTS
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PRINT_STAR: PHA
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LDA #'*'
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JSR ECHO
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PLA
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RTS
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PRINT_BLANK: PHA
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LDA #' '
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JSR ECHO
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PLA
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RTS
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NEXT_ROW: PHA
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LDA #$0d
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JSR ECHO
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PLA
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RTS
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;from HeartPicture
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;to PIC_ADDRESS ($88)
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COPY_HEART: PHA
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TXA
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PHA
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LDX #PIC_HEIGHT
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COPY_LOOP: LDA HeartPicture, X
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STA PIC_ADDRESS, X
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DEX
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BPL COPY_LOOP
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PLA
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TAX
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PLA
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RTS
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HeartPicture:
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.byte %00000000
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.byte %01100110
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.byte %11111111
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.byte %11111111
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.byte %11111111
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.byte %01111110
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.byte %00111100
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.byte %00011000
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SmileyPicture: .byte $3c, $42, $a5, $81, $a5, $99, $42, $3c
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WozPicture: .byte $88, $a8, $50, $07, $61, $92, $94, $67
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SmartyLogo: .byte $ff, $81, $bd, $bd, $bd, $bd, $81, $ff
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RocketPicture: .byte $18, $24, $24, $24, $7e, $a5, $FF, $a5
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.byte "8*8 Pixel Art program end", $0d, $00 |