42 lines
802 B
ArmAsm
42 lines
802 B
ArmAsm
.define Cmi4
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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 on fourbyte integers.
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! If T is pushed first 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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Cmi4:
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jsr Sbi4 ! subtract operands (T - S)
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jsr Pop ! get result (lowbyte, lowbyte+1)
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stx ARTH ! store lowbyte
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sta ARTH+1 ! store lowbyte+1
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jsr Pop ! get result (lowbyte+2, lowbyte+3)
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tay ! test lowbyte+3
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bpl 1f ! S >= T
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lda #0x0FF ! S < T
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tax ! AX becomes -1
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rts
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1: cmp #0 ! test lowbyte+3 on zero
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bne 2f
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cpx #0 ! test lowbyte+2 on zero
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bne 2f
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lda #0
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cmp ARTH+1 ! test lowbyte+1 on zero
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bne 2f
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cmp ARTH ! test lowbyte on zero
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bne 2f
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lda #0 ! S = T
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tax ! AX becomes 0
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rts
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2: lda #0 ! S > T
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ldx #1 ! AX becomes 1
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rts
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