murmurhash2算法 和 DJB Hash算法是目前最流行的hash算法
1.DJB HASH算法
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/* the famous DJB Hash Function for strings */
unsigned int DJBHash(char *str)
{
unsigned int hash = 5381;
while (*str){
hash = ((hash << 5) + hash) + (*str++); /* times 33 */
}
hash &= ~(1 << 31); /* strip the highest bit */
return hash;
}
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2.murmurhash2
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uint32_t
murmur_hash2(char *data, size_t len)
{
uint32_t h, k;
h = 0 ^ len;
while (len >= 4) {
k = data[0];
k |= data[1] << 8;
k |= data[2] << 16;
k |= data[3] << 24;
k *= 0x5bd1e995;
k ^= k >> 24;
k *= 0x5bd1e995;
h *= 0x5bd1e995;
h ^= k;
data += 4;
len -= 4;
}
switch (len) {
case 3:
h ^= data[2] << 16;
case 2:
h ^= data[1] << 8;
case 1:
h ^= data[0];
h *= 0x5bd1e995;
}
h ^= h >> 13;
h *= 0x5bd1e995;
h ^= h >> 15;
return h;
}
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http://daodaoliang.com/c-%E5%AD%A6%E4%B9%A0/2017/03/08/c-%E5%AD%A6%E4%B9%A0-2017-03-08-HashAlgorithm/