ack/mach/6500/libem/cmu.s

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1984-12-17 11:03:13 +00:00
.define Cmu2
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.sect .text
.sect .rom
.sect .data
.sect .bss
.sect .text
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! This subroutine compares two unsigned twobyte integers.
! If T is the first pushed and than S, the routine will return:
! -1 if S < T,
! 0 if S = T,
! 1 if S > T.
Cmu2:
stx EXG ! S (lowbyte)
sta EXG+1 ! S (highbyte)
jsr Pop ! get T
cmp EXG+1
beq 2f ! S (highbyte) = T (highbyte)
bcc 1f
4: lda #0 ! S > T
ldx #1
rts
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1: lda #0xFF ! S < T
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tax
rts
2: cpx EXG
bne 3f
lda #0 ! S = T
tax
rts
3: bcc 1b
bcs 4b