AppleIIAsm-Collection/source/d2_stdio/T.SUB.TVLINE
nathanriggs 9f35f32f67 Revision 0.5.0
- massive overhaul of architecture
- first round of optimizations
- first draft of the technical manual for the entire library
- reorganization of directory structure
2019-09-27 16:57:34 -04:00

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*
*``````````````````````````````*
* TVLINE (NATHAN RIGGS) *
* *
* INPUT: *
* *
* ]X1 STORED AT WPAR1 *
* ]Y1 STORED AT WPAR2 *
* ]Y2 STORED AT WPAR2+1 *
* ]F STORED AT BPAR1 *
* *
* OUTPUT: VERT LINE TO SCREEN *
* *
* DESTROY: AXYNVBDIZCMS *
* ^^^^^ ^^^ *
* *
* CYCLES: 33+ *
* SIZE: 34 BYTES *
*,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,*
*
]X1 EQU WPAR1 ; 1 BYTE
]Y1 EQU WPAR2 ; 1 BYTE
]Y2 EQU WPAR2+1 ; 1 BYTE
]F EQU BPAR1 ; 1 BYTE
*
TVLINE
*
LDA ]Y1
LDY ]X1
:LOOP
JSR GBCALC ; GET POS SCREEN ADDRESS
LDA ]F
STA (GBPSH),Y ; PLOT TO SCREEN MEMORY
INC ]Y1
LDA ]Y1
CMP ]Y2 ; IF Y1 < Y2
BNE :LOOP ; LOOP; ELSE, CONTINUE
:EXIT
RTS