83 lines
1020 B
ArmAsm
83 lines
1020 B
ArmAsm
;=========================================================
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; gr_make_quake
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;=========================================================
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; Take image in $c00
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; Copy to $BC00
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; Actually copy lines 2..41 to 0..39
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gr_make_quake:
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ldx #0
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make_quake_loop:
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lda gr_offsets,x
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sta OUTL
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lda gr_offsets+1,x
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clc
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adc #$B8
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sta OUTH
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inx
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inx
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lda gr_offsets,x
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sta INL
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lda gr_offsets+1,x
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clc
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adc #$8
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sta INH
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ldy #39
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quake_inner:
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lda (INL),Y
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sta (OUTL),Y
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dey
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bpl quake_inner
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cpx #40
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bne make_quake_loop
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; write zeros to the rest
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quake_clear_bottom:
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lda gr_offsets,x
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sta OUTL
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lda gr_offsets+1,x
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clc
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adc #$B8
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sta OUTH
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inx
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inx
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ldy #39
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lda #0
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quake_clear_inner:
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sta (OUTL),Y
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dey
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bpl quake_clear_inner
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cpx #48
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bne quake_clear_bottom
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; clear the extra two lines from the original
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quake_clear_extra:
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ldx #40
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lda gr_offsets,x
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sta OUTL
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lda gr_offsets+1,x
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clc
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adc #$8
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sta OUTH
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ldy #39
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lda #0
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quake_clear_extra_inner:
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sta (OUTL),Y
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dey
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bpl quake_clear_extra_inner
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rts ; 6
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