1984-12-17 11:03:13 +00:00
|
|
|
.define Ngi4
|
1987-01-30 18:41:42 +00:00
|
|
|
.sect .text
|
|
|
|
|
.sect .rom
|
|
|
|
|
.sect .data
|
|
|
|
|
.sect .bss
|
|
|
|
|
.sect .text
|
1984-12-17 11:03:13 +00:00
|
|
|
|
|
|
|
|
! 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
|
1988-08-19 17:05:03 +00:00
|
|
|
eor #0x0FF ! one's complement lowbyte+y
|
1984-12-17 11:03:13 +00:00
|
|
|
sta (ADDR),y
|
|
|
|
|
dey
|
|
|
|
|
bpl 1b
|
1988-08-19 17:05:03 +00:00
|
|
|
ldx #0x0FD
|
1984-12-17 11:03:13 +00:00
|
|
|
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
|
|
|
|
|
|
|
|
|
|
|
