mirror of
https://github.com/cc65/cc65.git
synced 2024-10-20 23:24:14 +00:00
24 lines
491 B
ArmAsm
24 lines
491 B
ArmAsm
|
;
|
||
|
; void clrscr (void);
|
||
|
;
|
||
|
.export _clrscr
|
||
|
.include "c1p.inc"
|
||
|
|
||
|
; Adapted from the Challenger Character Graphics
|
||
|
; Reference Manual, "2.3.3 MACHINE LANGUAGE SCREEN CLEAR"
|
||
|
; This is self-modifying code!
|
||
|
BANKS = VIDEORAMSIZE / $100
|
||
|
|
||
|
_clrscr: LDA #$20 ;' '
|
||
|
LDY #BANKS
|
||
|
LDX #$00
|
||
|
STALOC: STA SCRNBASE,X
|
||
|
INX
|
||
|
BNE STALOC
|
||
|
INC STALOC+2
|
||
|
DEY
|
||
|
BNE STALOC
|
||
|
LDA #>(SCRNBASE) ; load high byte
|
||
|
STA STALOC+2 ; restore base address
|
||
|
RTS
|