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Emulate _BitScanForward64 on WIN32 #118

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Merged
merged 1 commit into from
Feb 22, 2015
Merged

Emulate _BitScanForward64 on WIN32 #118

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13 changes: 10 additions & 3 deletions format.h
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Original file line number Diff line number Diff line change
Expand Up @@ -56,15 +56,22 @@ inline uint32_t clz(uint32_t x) {
return 31 - r;
}
# define FMT_BUILTIN_CLZ(n) fmt::internal::clz(n)
# ifdef _WIN64
# pragma intrinsic(_BitScanReverse64)
inline uint32_t clzll(uint64_t n) {
unsigned long r = 0;
# ifdef _WIN64
# pragma intrinsic(_BitScanReverse64)
_BitScanReverse64(&r, x);
# else
// Scan the high 32 bits.
if (_BitScanReverse(&r, static_cast<uint32_t>(n >> 32)))
return 63 - (r + 32);

// Scan the low 32 bits.
_BitScanReverse(&r, static_cast<uint32_t>(n));
# endif
return 63 - r;
}
# define FMT_BUILTIN_CLZLL(n) fmt::internal::clzll(n)
# endif
}
}
#endif
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