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Find one clear bit 64 bits at a time. (#444)

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This commit is contained in:
Branimir Karadžić
2026-10-04 20:21:29 -07:00
committed by GitHub
parent 8633996da6
commit 9521d0b5e2
2 changed files with 53 additions and 0 deletions
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24
src/bitarray.cpp
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@@ -606,8 +606,32 @@ namespace bx
return _endBit;
}
inline uint32_t bitSetFindZero(const uint64_t* _ptr, uint32_t _beginBit, uint32_t _endBit)
{
const uint32_t begin = _beginBit/64;
for (uint32_t ii = begin, end = alignUp(_endBit, 64)/64; ii < end; ++ii)
{
uint64_t zeros = ~_ptr[ii];
zeros &= ii == begin ? UINT64_MAX << (_beginBit & 63) : UINT64_MAX;
if (0 != zeros)
{
const uint32_t idx = ii*64 + countTrailingZeros(zeros);
return idx < _endBit ? idx : kInvalid;
}
}
return kInvalid;
}
inline uint32_t bitSetFind(const uint64_t* _ptr, uint32_t _beginBit, uint32_t _endBit, uint32_t _numBits)
{
if (1 == _numBits)
{
return bitSetFindZero(_ptr, _beginBit, _endBit);
}
if (_numBits >= 127)
{
const uint32_t idx = bitSetFindT<uint64_t>(_ptr, _beginBit, _endBit, (_numBits+63)>>6);