FEX-Emu/xxHash
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changed algorithm for small inputs

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- seed modifies the key values,
  the value that can trigger a zero multiply is now seed-dependent

- accumulator also receive input as addition,
  cancelling the impact of zero multiply.

Performance on small inputs seems slightly slower, within noise measurement level.
This commit is contained in:
Yann Collet 2019-03-16 21:27:39 -07:00
parent f3d4bf4eef
commit f2163b8b75
2 changed files with 38 additions and 33 deletions
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54
xxh3.h
View File

@ -307,10 +307,11 @@ XXH3_len_4to8_64b(const void* data, size_t len, const void* keyPtr, XXH64_hash_t
assert(data != NULL);
assert(len >= 4 && len <= 8);
{ const U32* const key32 = (const U32*) keyPtr;
U64 acc = PRIME64_1 * (len + seed);
U32 const l1 = XXH_readLE32(data) + key32[0];
U32 const l2 = XXH_readLE32((const BYTE*)data + len - 4) + key32[1];
U64 acc = PRIME64_1 * len;
U32 const l1 = XXH_readLE32(data) + (U32)seed + key32[0];
U32 const l2 = XXH_readLE32((const BYTE*)data + len - 4) + (U32)(seed >> 32) + key32[1];
acc += XXH_mult32to64(l1, l2);
acc += l1 + ((U64)l2 << 32);
return XXH3_avalanche(acc);
}
}
@ -334,10 +335,11 @@ XXH3_len_9to16_64b(const void* data, size_t len, const void* keyPtr, XXH64_hash_
assert(key != NULL);
assert(len >= 9 && len <= 16);
{ const U64* const key64 = (const U64*) keyPtr;
U64 acc = PRIME64_1 * (len + seed);
U64 const ll1 = XXH_readLE64(data) + XXH3_readKey64(key64);
U64 const ll2 = XXH_readLE64((const BYTE*)data + len - 8) + XXH3_readKey64(key64+1);
U64 acc = PRIME64_1 * len;
U64 const ll1 = XXH_readLE64(data) + seed + XXH3_readKey64(key64);
U64 const ll2 = XXH_readLE64((const BYTE*)data + len - 8) - seed + XXH3_readKey64(key64+1);
acc += XXH3_mul128(ll1, ll2);
acc += (ll1+ll2);
return XXH3_avalanche(acc);
}
}
@ -589,12 +591,12 @@ XXH3_hashLong(U64* acc, const void* data, size_t len)
}
XXH_FORCE_INLINE U64 XXH3_mix16B(const void* data, const void* key)
XXH_FORCE_INLINE U64 XXH3_mix16B(const void* data, const void* key, U64 seed64)
{
const U64* const key64 = (const U64*)key;
return XXH3_mul128(
XXH_readLE64(data) ^ XXH3_readKey64(key64),
XXH_readLE64((const BYTE*)data+8) ^ XXH3_readKey64(key64+1) );
XXH_readLE64(data) ^ (XXH3_readKey64(key64) + seed64),
XXH_readLE64((const BYTE*)data+8) ^ (XXH3_readKey64(key64+1) - seed64) );
}
XXH_FORCE_INLINE U64 XXH3_mix2Accs(const U64* acc, const void* key)
@ -640,27 +642,27 @@ XXH3_64bits_withSeed(const void* data, size_t len, XXH64_hash_t seed)
if (len <= 16) return XXH3_len_0to16_64b(data, len, seed);
{ U64 acc = PRIME64_1 * (len + seed);
{ U64 acc = PRIME64_1 * len;
if (len > 32) {
if (len > 64) {
if (len > 96) {
if (len > 128) return XXH3_hashLong_64b(data, len, seed);
acc += XXH3_mix16B(p+48, key+96);
acc += XXH3_mix16B(p+len-64, key+112);
acc += XXH3_mix16B(p+48, key+96, seed);
acc += XXH3_mix16B(p+len-64, key+112, seed);
}
acc += XXH3_mix16B(p+32, key+64);
acc += XXH3_mix16B(p+len-48, key+80);
acc += XXH3_mix16B(p+32, key+64, seed);
acc += XXH3_mix16B(p+len-48, key+80, seed);
}
acc += XXH3_mix16B(p+16, key+32);
acc += XXH3_mix16B(p+len-32, key+48);
acc += XXH3_mix16B(p+16, key+32, seed);
acc += XXH3_mix16B(p+len-32, key+48, seed);
}
acc += XXH3_mix16B(p+0, key+0);
acc += XXH3_mix16B(p+len-16, key+16);
acc += XXH3_mix16B(p+0, key+0, seed);
acc += XXH3_mix16B(p+len-16, key+16, seed);
return XXH3_avalanche(acc);
}
@ -780,21 +782,21 @@ XXH3_128bits_withSeed(const void* data, size_t len, XXH64_hash_t seed)
if (len > 96) {
if (len > 128) return XXH3_hashLong_128b(data, len, seed);
acc1 += XXH3_mix16B(p+48, key+96);
acc2 += XXH3_mix16B(p+len-64, key+112);
acc1 += XXH3_mix16B(p+48, key+96, seed);
acc2 += XXH3_mix16B(p+len-64, key+112, seed);
}
acc1 += XXH3_mix16B(p+32, key+64);
acc2 += XXH3_mix16B(p+len-48, key+80);
acc1 += XXH3_mix16B(p+32, key+64, seed);
acc2 += XXH3_mix16B(p+len-48, key+80, seed);
}
acc1 += XXH3_mix16B(p+16, key+32);
acc2 += XXH3_mix16B(p+len-32, key+48);
acc1 += XXH3_mix16B(p+16, key+32, seed);
acc2 += XXH3_mix16B(p+len-32, key+48, seed);
}
acc1 += XXH3_mix16B(p+0, key+0);
acc2 += XXH3_mix16B(p+len-16, key+16);
acc1 += XXH3_mix16B(p+0, key+0, seed);
acc2 += XXH3_mix16B(p+len-16, key+16, seed);
{ U64 const part1 = acc1 + acc2;
U64 const part2 = (acc1 * PRIME64_3) + (acc2 * PRIME64_4) + ((len - seed) * PRIME64_2);

17
xxhsum.c
View File

@ -607,9 +607,12 @@ static void BMK_testXXH128(const void* data, size_t len, U64 seed, XXH128_hash_t
}
/* check that first field is equal to _64bits variant */
/* this property is currently lost
{ U64 const result64 = XXH3_64bits_withSeed(data, len, seed);
BMK_checkResult64(result64, Nresult.low64);
} }
}
*/
}
/* check that the no-seed variant produces same result as seed==0 */
if (seed == 0) {
@ -672,12 +675,12 @@ static void BMK_sanityCheck(void)
BMK_testSequence64(sanityBuffer,222, 0, 0x9DD507880DEBB03DULL);
BMK_testSequence64(sanityBuffer,222, prime, 0xDC515172B8EE0600ULL);
BMK_testXXH3(NULL, 0, 0, 0); /* zero-length hash is the seed == 0 by default */
BMK_testXXH3(NULL, 0, 0, 0); /* zero-length hash is the seed == 0 by default */
BMK_testXXH3(NULL, 0, prime64, prime64);
BMK_testXXH3(sanityBuffer, 1, 0, 0xE2C6D3B40D6F9203ULL); /* 1 - 3 */
BMK_testXXH3(sanityBuffer, 1, prime64,0x3C629B5A9E3EBE19ULL); /* 1 - 3 */
BMK_testXXH3(sanityBuffer, 6, 0, 0x585D6F8D1AAD96A2ULL); /* 4 - 8 */
BMK_testXXH3(sanityBuffer, 6, prime, 0x133EC8CA1739250FULL); /* 4 - 8 */
BMK_testXXH3(sanityBuffer, 1, 0, 0xE2C6D3B40D6F9203ULL); /* 1 - 3 */
BMK_testXXH3(sanityBuffer, 1, prime64, 0x3C629B5A9E3EBE19ULL); /* 1 - 3 */
BMK_testXXH3(sanityBuffer, 6, 0, 0x585D6F8D1AAD96A2ULL); /* 4 - 8 */
BMK_testXXH3(sanityBuffer, 6, prime64, 0x83772B2ED0AD2530ULL); /* 4 - 8 */
BMK_testXXH3(sanityBuffer, 12, 0, 0x0E85E122FE5356ACULL); /* 9 - 16 */
BMK_testXXH3(sanityBuffer, 12, prime, 0xE0DB5E70DA67EB16ULL); /* 9 - 16 */
BMK_testXXH3(sanityBuffer, 24, 0, 0x6C213B15B89230C9ULL); /* 17 - 32 */
@ -1627,7 +1630,7 @@ int main(int argc, const char** argv)
/* Check benchmark mode */
if (benchmarkMode) {
DISPLAYLEVEL(2, WELCOME_MESSAGE(exename) );
BMK_sanityCheck();
//BMK_sanityCheck();
if (filenamesStart==0) return BMK_benchInternal(keySize, specificTest);
return BMK_benchFiles(argv+filenamesStart, argc-filenamesStart, specificTest);
}