/*
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
*
* Copyright 2021 Mike Becker, Olaf Wintermann All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include "cx/hash_key.h"
#include <string.h>
void cx_hash_murmur(CxHashKey *key) {
unsigned char const *data = key->data;
if (data == NULL) {
// extension: special value for NULL
key->hash = 1574210520u;
return;
}
size_t len = key->len;
unsigned m = 0x5bd1e995;
unsigned r = 24;
unsigned h = 25 ^ len;
unsigned i = 0;
while (len >= 4) {
unsigned k = data[i + 0] & 0xFF;
k |= (data[i + 1] & 0xFF) << 8;
k |= (data[i + 2] & 0xFF) << 16;
k |= (data[i + 3] & 0xFF) << 24;
k *= m;
k ^= k >> r;
k *= m;
h *= m;
h ^= k;
i += 4;
len -= 4;
}
switch (len) {
case 3:
h ^= (data[i + 2] & 0xFF) << 16;
__attribute__((__fallthrough__));
case 2:
h ^= (data[i + 1] & 0xFF) << 8;
__attribute__((__fallthrough__));
case 1:
h ^= (data[i + 0] & 0xFF);
h *= m;
__attribute__((__fallthrough__));
default: // do nothing
;
}
h ^= h >> 13;
h *= m;
h ^= h >> 15;
key->hash = h;
}
CxHashKey cx_hash_key_str(char const *str) {
CxHashKey key;
key.data = str;
key.len = str == NULL ? 0 : strlen(str);
cx_hash_murmur(&key);
return key;
}
CxHashKey cx_hash_key_bytes(
unsigned char const *bytes,
size_t len
) {
CxHashKey key;
key.data = bytes;
key.len = len;
cx_hash_murmur(&key);
return key;
}
CxHashKey cx_hash_key(
void const *obj,
size_t len
) {
CxHashKey key;
key.data = obj;
key.len = len;
cx_hash_murmur(&key);
return key;
}