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29 lines
394 B
ArmAsm
29 lines
394 B
ArmAsm
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; Ullrich von Bassewitz, 25.10.2000
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; CC65 runtime: Decrement the stackpointer by value in y
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.export subysp
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.importzp sp, tmp1
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.proc subysp
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pha ; Save A
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sty tmp1 ; Save the value
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lda sp ; Get lo byte
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sec
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sbc tmp1 ; Subtract y value
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sta sp ; Put result back
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bcs @L1
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dec sp+1
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@L1: pla ; Restore A
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rts ; Done
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.endproc
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