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BitUtils: Implement CountTrailingZeros

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This commit is contained in:
Merry
2022-07-07 22:57:21 +01:00
parent 4d99506b4c
commit 20ccc38f0f
1 changed files with 50 additions and 0 deletions
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50
Source/Core/Common/BitUtils.h
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@ -411,6 +411,56 @@ constexpr int CountLeadingZeros(uint32_t value)
#endif
}
template <typename T>
constexpr int CountTrailingZerosConst(T value)
{
int result = sizeof(T) * 8;
while (value)
{
result--;
value <<= 1;
}
return result;
}
constexpr int CountTrailingZeros(uint64_t value)
{
#if defined(__GNUC__)
return value ? __builtin_ctzll(value) : 64;
#elif defined(_MSC_VER)
if (std::is_constant_evaluated())
{
return CountTrailingZerosConst(value);
}
else
{
unsigned long index = 0;
return _BitScanForward64(&index, value) ? index : 64;
}
#else
return CountTrailingZerosConst(value);
#endif
}
constexpr int CountTrailingZeros(uint32_t value)
{
#if defined(__GNUC__)
return value ? __builtin_ctz(value) : 32;
#elif defined(_MSC_VER)
if (std::is_constant_evaluated())
{
return CountTrailingZerosConst(value);
}
else
{
unsigned long index = 0;
return _BitScanForward(&index, value) ? index : 32;
}
#else
return CountLeadingZerosConst(value);
#endif
}
#undef CONSTEXPR_FROM_INTRINSIC
template <typename T>