72 lines
900 B
ArmAsm
72 lines
900 B
ArmAsm
.define Duv4
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.sect .text
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.sect .rom
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.sect .data
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.sect .bss
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.sect .text
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! This subroutine performs an unsigned division on two fourbyte
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! unsigned integers.
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! For more details see dvi.s
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! The only difference is that zeropage locations are twice as big.
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Duv4:
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1: ldy #0
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sty ARTH+8
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sty ARTH+9
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sty ARTH+10
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sty ARTH+11
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ldy #33
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4: lda ARTH+11
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cmp ARTH+3
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bcc 1f ! no sub
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bne 2f ! sub
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lda ARTH+10
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cmp ARTH+2
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bcc 1f
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bne 2f
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lda ARTH+9
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cmp ARTH+1
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bcc 1f
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bne 2f
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lda ARTH+8
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cmp ARTH
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bcc 1f
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2: sec
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lda ARTH+8
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sbc ARTH
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sta ARTH+8
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lda ARTH+9
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sbc ARTH+1
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sta ARTH+9
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lda ARTH+10
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sbc ARTH+2
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sta ARTH+10
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lda ARTH+11
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sbc ARTH+3
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sta ARTH+11
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sec
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rol ARTH+4
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bne 3f
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1: asl ARTH+4
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3: rol ARTH+5
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rol ARTH+6
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rol ARTH+7
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rol ARTH+8
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rol ARTH+9
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rol ARTH+10
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rol ARTH+11
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dey
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bne 4b
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ldy UNSIGN
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beq 1f
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ldy SIGN
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beq 1f
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lda #0
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ldx #ARTH+4
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jsr Ngi4
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1: rts
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