mirror of
https://github.com/nathanriggs/AppleIIAsm-Collection.git
synced 2024-06-01 15:41:27 +00:00
40 lines
1.3 KiB
NASM
40 lines
1.3 KiB
NASM
*
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*``````````````````````````````*
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* TVLINE (NATHAN RIGGS) *
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* *
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* INPUT: *
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* *
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* ZPW1 = X POSITION *
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* ZPW2 = Y ORIGIN *
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* ZPW2+1 = Y DESTINATION *
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* ZPB1 = FILL CHARACTER *
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* *
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* OUTPUT: VERT LINE TO SCREEN *
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* *
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* DESTROY: NZCIDV *
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* ^^^ ^ *
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* *
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* CYCLES: 77+ *
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* SIZE: 26 BYTES *
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*,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,*
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*
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]X1 EQU ZPW1 ; X COLUMN OF LINE
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]Y1 EQU ZPW2 ; Y POSITION ORIGIN
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]Y2 EQU ZPW2+1 ; Y POSITION DESTINATION
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]F EQU ZPB1 ; LINE FILL CHARACTER
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*
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TVLINE
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*
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LDA ]Y1 ; {4C3B} LOAD Y ORIGIN {NZ}
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LDY ]X1 ; {4C3B} LOAD X POSITION {NZ}
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:LOOP
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JSR GBCALC ; {43C3B} GET POS SCREEN ADDRESS {NZCV}
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LDA ]F ; {4C3B} LOAD FILL CHARACTER {NZ}
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STA (GBPSH),Y ; {6C2B} PLOT TO SCREEN MEMORY
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INC ]Y1 ; {6C3B} INCREASE Y POSITION {NZ}
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LDA ]Y1 ; {4C3B} RELOAD Y POSITION {NZ}
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CMP ]Y2 ; {4C3B} IF Y1 < Y2 {NZC}
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BNE :LOOP ; {3C2B} LOOP; ELSE, CONTINUE
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:EXIT
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RTS ; {6C1B}
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