50 lines
939 B
ArmAsm
50 lines
939 B
ArmAsm
.define Cmu4
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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 compares two unsigned fourbyte integers.
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! If T is first pushed and than S the routine will return:
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! -1 if S < T,
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! 0 if S = T,
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! 1 if S > T.
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Cmu4:
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lda #ARTH
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sta ADDR
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lda #0
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sta ADDR+1
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jsr Sdo ! store S in zeropage ARTH - ARTH+3
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lda #ARTH+4
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sta ADDR
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jsr Sdo ! store T in zeropage ARTH+4 - ARTH+7
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lda ARTH+7
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cmp ARTH+3
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bcc 3f ! S (lowbyte+3) < T (lowbyte+3)
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bne 2f ! S (lowbyte+3) < T (lowbyte+3)
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lda ARTH+6
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cmp ARTH+2
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bcc 3f ! S (lowbyte+2) < T (lowbyte+2)
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bne 2f ! S (lowbyte+2) < T (lowbyte+2)
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lda ARTH+5
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cmp ARTH+1
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bcc 3f ! S (lowbyte+1) < T (lowbyte+1)
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bne 2f ! S (lowbyte+1) < T (lowbyte+1)
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lda ARTH+4
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cmp ARTH
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bcc 3f ! S (lowbyte+0) < T (lowbyte+0)
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bne 2f ! S (lowbyte+0) < T (lowbyte+0)
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lda #0
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tax ! S = T
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rts
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2: lda #0 ! S > T
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ldx #1
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rts
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3: lda #0x0FF ! S < T
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tax
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rts
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