mirror of
https://github.com/cc65/cc65.git
synced 2024-12-25 02:29:52 +00:00
73 lines
1.4 KiB
ArmAsm
73 lines
1.4 KiB
ArmAsm
;
|
|
; Written by Groepaz/Hitmen <groepaz@gmx.net>
|
|
; Cleanup by Ullrich von Bassewitz <uz@cc65.org>
|
|
;
|
|
; void clrscr (void);
|
|
;
|
|
|
|
.export _clrscr
|
|
.import ppubuf_waitempty
|
|
|
|
.include "nes.inc"
|
|
|
|
|
|
.proc _clrscr
|
|
|
|
; wait until all console data has been written
|
|
|
|
jsr ppubuf_waitempty
|
|
|
|
; wait for vblank
|
|
|
|
lda #0
|
|
sta VBLANK_FLAG
|
|
@w2: lda VBLANK_FLAG
|
|
beq @w2
|
|
|
|
; switch screen off
|
|
|
|
lda #%00000000
|
|
sta PPU_CTRL2
|
|
|
|
; Set start address to Name Table #1
|
|
|
|
lda #$20
|
|
sta PPU_VRAM_ADDR2
|
|
lda #$00
|
|
sta PPU_VRAM_ADDR2
|
|
|
|
; Clear Name Table #1
|
|
|
|
lda #' '
|
|
ldx #$f0 ; 4*$f0=$03c0
|
|
|
|
beg: sta PPU_VRAM_IO
|
|
sta PPU_VRAM_IO
|
|
sta PPU_VRAM_IO
|
|
sta PPU_VRAM_IO
|
|
dex
|
|
bne beg
|
|
|
|
lda #$23 ;
|
|
sta PPU_VRAM_ADDR2 ; Set start address to PPU address $23C0
|
|
lda #$C0 ; (1st attribute table)
|
|
sta PPU_VRAM_ADDR2
|
|
|
|
ldx #$00
|
|
|
|
lll: lda #$00 ; Write attribute table value and auto increment
|
|
sta PPU_VRAM_IO ; to next address
|
|
inx
|
|
cpx #$40
|
|
bne lll
|
|
|
|
; switch screen on again
|
|
|
|
lda #%00011110
|
|
sta PPU_CTRL2
|
|
rts
|
|
|
|
.endproc
|
|
|
|
|