universe@563: /*
universe@563:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
universe@563:  *
universe@563:  * Copyright 2021 Mike Becker, Olaf Wintermann All rights reserved.
universe@563:  *
universe@563:  * Redistribution and use in source and binary forms, with or without
universe@563:  * modification, are permitted provided that the following conditions are met:
universe@563:  *
universe@563:  *   1. Redistributions of source code must retain the above copyright
universe@563:  *      notice, this list of conditions and the following disclaimer.
universe@563:  *
universe@563:  *   2. Redistributions in binary form must reproduce the above copyright
universe@563:  *      notice, this list of conditions and the following disclaimer in the
universe@563:  *      documentation and/or other materials provided with the distribution.
universe@563:  *
universe@563:  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
universe@563:  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
universe@563:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
universe@563:  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
universe@563:  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
universe@563:  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
universe@563:  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
universe@563:  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
universe@563:  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
universe@563:  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
universe@563:  * POSSIBILITY OF SUCH DAMAGE.
universe@563:  */
universe@563: 
universe@563: #include "cx/hash_key.h"
universe@563: #include <string.h>
universe@563: 
universe@563: void cx_hash_murmur(CxHashKey *key) {
universe@690:     unsigned char const *data = key->data;
universe@604:     if (data == NULL) {
universe@628:         // extension: special value for NULL
universe@604:         key->hash = 1574210520u;
universe@604:         return;
universe@604:     }
universe@563:     size_t len = key->len;
universe@563: 
universe@563:     unsigned m = 0x5bd1e995;
universe@563:     unsigned r = 24;
universe@563:     unsigned h = 25 ^ len;
universe@563:     unsigned i = 0;
universe@563:     while (len >= 4) {
universe@563:         unsigned k = data[i + 0] & 0xFF;
universe@563:         k |= (data[i + 1] & 0xFF) << 8;
universe@563:         k |= (data[i + 2] & 0xFF) << 16;
universe@563:         k |= (data[i + 3] & 0xFF) << 24;
universe@563: 
universe@563:         k *= m;
universe@563:         k ^= k >> r;
universe@563:         k *= m;
universe@563: 
universe@563:         h *= m;
universe@563:         h ^= k;
universe@563: 
universe@563:         i += 4;
universe@563:         len -= 4;
universe@563:     }
universe@563: 
universe@563:     switch (len) {
universe@563:         case 3:
universe@563:             h ^= (data[i + 2] & 0xFF) << 16;
universe@563:                     __attribute__((__fallthrough__));
universe@563:         case 2:
universe@563:             h ^= (data[i + 1] & 0xFF) << 8;
universe@563:                     __attribute__((__fallthrough__));
universe@563:         case 1:
universe@563:             h ^= (data[i + 0] & 0xFF);
universe@563:             h *= m;
universe@563:                     __attribute__((__fallthrough__));
universe@628:         default: // do nothing
universe@678:             ;
universe@563:     }
universe@563: 
universe@563:     h ^= h >> 13;
universe@563:     h *= m;
universe@563:     h ^= h >> 15;
universe@563: 
universe@563:     key->hash = h;
universe@563: }
universe@563: 
universe@563: CxHashKey cx_hash_key_str(char const *str) {
universe@563:     CxHashKey key;
universe@690:     key.data = str;
universe@604:     key.len = str == NULL ? 0 : strlen(str);
universe@563:     cx_hash_murmur(&key);
universe@563:     return key;
universe@563: }
universe@563: 
universe@563: CxHashKey cx_hash_key_bytes(
universe@563:         unsigned char const *bytes,
universe@563:         size_t len
universe@563: ) {
universe@563:     CxHashKey key;
universe@690:     key.data = bytes;
universe@563:     key.len = len;
universe@563:     cx_hash_murmur(&key);
universe@563:     return key;
universe@563: }
universe@563: 
universe@563: CxHashKey cx_hash_key(
universe@603:         void const *obj,
universe@563:         size_t len
universe@563: ) {
universe@563:     CxHashKey key;
universe@690:     key.data = obj;
universe@563:     key.len = len;
universe@563:     cx_hash_murmur(&key);
universe@563:     return key;
universe@563: }