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37178d5141
that are set on startup. This is needed to support the C128, which can switch the screen size at runtime. git-svn-id: svn://svn.cc65.org/cc65/trunk@2042 b7a2c559-68d2-44c3-8de9-860c34a00d81
50 lines
586 B
ArmAsm
50 lines
586 B
ArmAsm
;
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; Ullrich von Bassewitz, 26.11.1998
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;
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; void clrscr (void);
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;
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.export _clrscr
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.import plot
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.importzp ptr1
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.include "pet.inc"
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_clrscr:
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; Set the screen base address
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lda #$00
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sta ptr1
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lda #$80
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sta ptr1+1
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; Determine, how many pages to fill
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ldx #4
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lda SCR_LINELEN ; Check length of one line
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cmp #40+1
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bcc L1
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ldx #8
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; Clear the screen
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L1: lda #$20 ; Screen code for blank
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ldy #$00
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L2: sta (ptr1),y
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iny
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bne L2
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inc ptr1+1
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dex
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bne L2
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; Set the cursor to 0/0
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lda #0
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sta CURS_X
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sta CURS_Y
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jmp plot
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rts
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