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36 lines
1.1 KiB
C
36 lines
1.1 KiB
C
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#ifndef INTERNAL_MULSC_H
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#define INTERNAL_MULSC_H
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#if !defined(_MSC_VER) || !defined(_M_IX86) || _MSC_VER >= 1800
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//#define MULSC(a, b) ((int)((LONG_LONG)(a) * (b) >> 16))
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//#define MULSC(a, b) ((a) * ((b) >> 2) >> 14)
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#define MULSCV(a, b) ((int)((LONG_LONG)(a) * (b) >> 32))
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#define MULSCA(a, b) ((int)((LONG_LONG)((a) << 4) * (b) >> 32))
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#define MULSC(a, b) ((int)((LONG_LONG)((a) << 4) * ((b) << 12) >> 32))
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#define MULSC16(a, b) ((int)((LONG_LONG)((a) << 12) * ((b) << 12) >> 32))
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#else
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/* VC++ calls __allmull and __allshr for the above math. I don't know why.
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* [Need to check if this still applies to recent versions of the compiler.] */
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static __forceinline unsigned long long MULLL(int a, int b)
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{
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__asm mov eax,a
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__asm imul b
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}
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static __forceinline int MULSCV (int a, int b)
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{
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#ifndef _DEBUG
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union { unsigned long long q; struct { int l, h; }; } val;
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val.q = MULLL(a,b);
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return val.h;
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#else
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__asm mov eax,a
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__asm imul b
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__asm mov eax,edx
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#endif
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}
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#define MULSCA(a, b) MULSCV((a) << 4, b)
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#define MULSC(a, b) MULSCV((a) << 4, (b) << 12)
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#define MULSC16(a, b) MULSCV((a) << 12, (b) << 12)
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#endif
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#endif /* INTERNAL_MULSC_H */
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