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63 lines
977 B
ArmAsm
63 lines
977 B
ArmAsm
;
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; Ullrich von Bassewitz, 14.09.2001
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;
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.export _clrscr
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.import plot
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.include "cbm510.inc"
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.include "extzp.inc"
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; ------------------------------------------------------------------------
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; void __fastcall__ clrscr (void);
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.proc _clrscr
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lda #0
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sta CURS_X
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sta CURS_Y
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jsr plot ; Set cursor to top left corner
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ldx #$00 ; Count
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jsr clearpage
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jsr clearpage
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jsr clearpage
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ldx #<(40*25) ; Count
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jsr clearpage ; Clear remainder of last page
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jmp plot ; Set screen pointer again
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.endproc
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.proc clearpage
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txa
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pha ; Save count
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lda #$20 ; Screencode for blank
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ldy #$00
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@L1: sta (SCREEN_PTR),y
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iny
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dex
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bne @L1
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inc SCREEN_PTR+1
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pla
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tax ; Reload count
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lda IndReg
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pha
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lda #$0F
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sta IndReg ; Switch to the system bank
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lda CHARCOLOR ; Load color
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ldy #$00
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@L2: sta (CRAM_PTR),y
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iny
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dex
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bne @L2
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inc CRAM_PTR+1
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pla
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sta IndReg ; Restore the old indirect bank
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rts
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.endproc
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