31 lines
385 B
ArmAsm
31 lines
385 B
ArmAsm
.define Ngi4
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! This subroutine takes a fourbyte interger and negates it.
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! For more details see ngi2.s
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Ngi4:
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sta ADDR+1
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stx ADDR
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ldy #3
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1: lda (ADDR),y
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eor #0FFh ! one's complement lowbyte+y
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sta (ADDR),y
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dey
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bpl 1b
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ldx #0FDh
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iny
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clc
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lda (ADDR),y
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adc #1
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sta (ADDR),y ! lowbyte+y
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1: iny
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lda (ADDR),y
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adc #0
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sta (ADDR),y ! (lowbyte+y)+0
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inx
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bne 1b
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rts
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