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