23 lines
424 B
ArmAsm
23 lines
424 B
ArmAsm
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.define Adi2
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! This subroutine adds two twobyte integers.
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! The first operand is on the top of the stack, the second operand
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! is in the AX registerpair.
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! The result is returned in registerpair AX.
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Adi2:
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sta ARTH+1 ! second operand (highbyte)
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stx ARTH ! second operand (lowbyte)
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jsr Pop ! get first operand
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pha ! save A
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clc
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txa
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adc ARTH ! add lowbytes
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tax
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pla ! get A
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adc ARTH+1 ! add the highbytes
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rts
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