23 lines
443 B
ArmAsm
23 lines
443 B
ArmAsm
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.sect .text
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! Exchange top two values on stack.
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! Stack: ( a b size -- b a )
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.define .exg
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.exg:
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lwz r3, 0(sp) ! r3 = size
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srwi r7, r3, 2
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mtspr ctr, r7 ! ctr = size / 4
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mr r4, sp ! r4 = pointer before value b
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add r5, r4, r3 ! r5 = pointer before value a
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! Loop to swap each pair of words.
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1: lwzu r6, 4(r4)
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lwzu r7, 4(r5)
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stw r6, 0(r5)
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stw r7, 0(r4)
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bdnz 1b ! loop ctr times
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addi sp, sp, 4 ! drop size from stack
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