36 lines
695 B
NASM
36 lines
695 B
NASM
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title pow2 - Danny's cheapo pow function
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;***
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;pow2.asm - compute 2 to the power of something
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;
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; Copyright (c) 1985-88, Microsoft Corporation
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;
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;Purpose:
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;
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;*******************************************************************************
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.xlist
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include cruntime.inc
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.list
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CODESEG
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pow2 proto stdcall, orig:qword
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public pow2
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pow2 proc stdcall, orig:qword
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fld orig
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fst st(1) ; duplicate orig
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frndint ; I don't care how it rounds
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fstp st(2) ; st=orig st(1)=round
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fsub st, st(1) ; st=orig-round
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f2xm1 ; st=2^(orig-round)-1
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fld1
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faddp st(1), st ; st=2^(orig-round)
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fscale ; st=2^(orig-round)*2^round=2^orig
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fstp st(1) ; clean stack of st(1)
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ret
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pow2 endp
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end
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