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C02/include/oric/screen.a02
2018-09-16 20:30:25 -04:00

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;Screen Control Assembly Lanuage Routines for Oric-1
;Clear the Screen
CLRSCR EQU $CC0A ;Basic CLS Routine (Atmos = $CCCE)
;Move Cursor to Home Position
CRSRHM: LDA #0 ;Set Args to 0,0
TAY ;and Fall into SETPOS
;Set Cursor Position
SETPOS: CLC
ADC #2 ;Add 2 to Column
PHA ;and Save It
INY ;Add 1 to Row
TYA ;and Save It
PHA
LDA #0 ;Turn Cursor Off
JSR $F7CB
PLA ;Retrieve Row
STA $0268 ;and Store in CURROW
PLA ;Retrieve Column
STA $0269 ;and Store in CURCOL
JSR $F67D ;Recalculate Screen Pointers
LDA #0 ;Turn Cursor On
JMP $F7CB ;and Return
;Get Cursor Position
GETPOS: LDA $0269 ;Load Column from CURCOL
SEC
SBC #2 ;Subtract 2
BPL GETPOY ;If Negative
LDA #0 ;set to 0
GETPOY: LDY $0268 ;Load Row from CURROW
DEY ;and Subtract 1
RTS
;Get Screen Size
GETSIZ: LDA #38 ;38 Columns (First 2 are Protected)
LDY #27 ;27 Rows
RTS