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murmurhash: always load byte by byte

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Also reverse the order of bytes, loading the most significant parts first,
and use bitwise "or" instead of addition.
This commit is contained in:
Peter Pentchev 2022-07-07 08:53:57 +03:00
parent 085973a486
commit ded97628f7
1 changed files with 1 additions and 5 deletions
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6
src/hash.cc
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@ -41,11 +41,7 @@ size_t hash_data(const char* input, size_t len)
for (ptrdiff_t i = -nblocks; i; ++i) for (ptrdiff_t i = -nblocks; i; ++i)
{ {
uint32_t key; uint32_t key;
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__ key = (blocks[4*i + 3] << 24) | (blocks[4*i + 2] << 16) | (blocks[4*i + 1] << 8) + blocks[4*i];
memcpy(&key, blocks + 4*i, 4);
#else
key = blocks[4*i] + (blocks[4*i + 1] << 8) + (blocks[4*i + 2] << 16) + (blocks[4*i + 3] << 24);
#endif
key *= c1; key *= c1;
key = rotl(key, 15); key = rotl(key, 15);
key *= c2; key *= c2;