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34 lines
633 B
ArmAsm
34 lines
633 B
ArmAsm
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; Christian Groessler, April 2014
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; mul20
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; multiplies A by 20 and returns result in AX
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; uses tmp4
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.importzp tmp4
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.export mul20,loc_tmp
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.proc mul20
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ldx #0
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stx tmp4
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sta loc_tmp
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asl a
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rol tmp4
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asl a
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rol tmp4 ; val * 4
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adc loc_tmp
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bcc L1
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inc tmp4 ; val * 5
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L1: asl a
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rol tmp4 ; val * 10
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asl a
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rol tmp4 ; val * 20
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ldx tmp4
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rts
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.endproc
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.bss
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loc_tmp:.res 1
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