forked from Qortal/Brooklyn
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
55 lines
1.3 KiB
55 lines
1.3 KiB
/* SPDX-License-Identifier: LGPL-2.1 |
|
* |
|
* Based on Paul Hsieh's (LGPG 2.1) hash function |
|
* From: http://www.azillionmonkeys.com/qed/hash.html |
|
*/ |
|
|
|
#define get16bits(d) (*((const __u16 *) (d))) |
|
|
|
static __always_inline |
|
__u32 SuperFastHash (const char *data, int len, __u32 initval) { |
|
__u32 hash = initval; |
|
__u32 tmp; |
|
int rem; |
|
|
|
if (len <= 0 || data == NULL) return 0; |
|
|
|
rem = len & 3; |
|
len >>= 2; |
|
|
|
/* Main loop */ |
|
#pragma clang loop unroll(full) |
|
for (;len > 0; len--) { |
|
hash += get16bits (data); |
|
tmp = (get16bits (data+2) << 11) ^ hash; |
|
hash = (hash << 16) ^ tmp; |
|
data += 2*sizeof (__u16); |
|
hash += hash >> 11; |
|
} |
|
|
|
/* Handle end cases */ |
|
switch (rem) { |
|
case 3: hash += get16bits (data); |
|
hash ^= hash << 16; |
|
hash ^= ((signed char)data[sizeof (__u16)]) << 18; |
|
hash += hash >> 11; |
|
break; |
|
case 2: hash += get16bits (data); |
|
hash ^= hash << 11; |
|
hash += hash >> 17; |
|
break; |
|
case 1: hash += (signed char)*data; |
|
hash ^= hash << 10; |
|
hash += hash >> 1; |
|
} |
|
|
|
/* Force "avalanching" of final 127 bits */ |
|
hash ^= hash << 3; |
|
hash += hash >> 5; |
|
hash ^= hash << 4; |
|
hash += hash >> 17; |
|
hash ^= hash << 25; |
|
hash += hash >> 6; |
|
|
|
return hash; |
|
}
|
|
|