60 lines
1.0 KiB
C
60 lines
1.0 KiB
C
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#ifndef strings_h
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#define strings_h
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/* MSVC doesn't define ffs/ffsl. This dummy strings.h header is provided
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* for both */
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#ifdef _MSC_VER
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# include <intrin.h>
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# pragma intrinsic(_BitScanForward)
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static __forceinline int ffsl(long x)
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{
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unsigned long i;
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if (_BitScanForward(&i, x))
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return (i + 1);
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return (0);
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}
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static __forceinline int ffs(int x)
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{
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return (ffsl(x));
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}
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# ifdef _M_X64
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# pragma intrinsic(_BitScanForward64)
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# endif
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static __forceinline int ffsll(unsigned __int64 x)
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{
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unsigned long i;
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#ifdef _M_X64
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if (_BitScanForward64(&i, x))
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return (i + 1);
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return (0);
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#else
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// Fallback for 32-bit build where 64-bit version not available
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// assuming little endian
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union {
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unsigned __int64 ll;
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unsigned long l[2];
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} s;
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s.ll = x;
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if (_BitScanForward(&i, s.l[0]))
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return (i + 1);
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else if(_BitScanForward(&i, s.l[1]))
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return (i + 33);
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return (0);
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#endif
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}
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#else
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# define ffsll(x) __builtin_ffsll(x)
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# define ffsl(x) __builtin_ffsl(x)
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# define ffs(x) __builtin_ffs(x)
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#endif
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#endif /* strings_h */
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