ucx: src/hash_key.c@69a83fad8a35

     1 /*

     2  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.

     3  *

     4  * Copyright 2021 Mike Becker, Olaf Wintermann All rights reserved.

     5  *

     6  * Redistribution and use in source and binary forms, with or without

     7  * modification, are permitted provided that the following conditions are met:

     8  *

     9  *   1. Redistributions of source code must retain the above copyright

    10  *      notice, this list of conditions and the following disclaimer.

    11  *

    12  *   2. Redistributions in binary form must reproduce the above copyright

    13  *      notice, this list of conditions and the following disclaimer in the

    14  *      documentation and/or other materials provided with the distribution.

    15  *

    16  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

    17  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

    18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

    19  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE

    20  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

    21  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

    22  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

    23  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN

    24  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

    25  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

    26  * POSSIBILITY OF SUCH DAMAGE.

    27  */

    29 #include "cx/hash_key.h"

    30 #include <string.h>

    32 void cx_hash_murmur(CxHashKey *key) {

    33     size_t len = key->len;

    34     unsigned char const *data = key->data.cbytes;

    36     unsigned m = 0x5bd1e995;

    37     unsigned r = 24;

    38     unsigned h = 25 ^ len;

    39     unsigned i = 0;

    40     while (len >= 4) {

    41         unsigned k = data[i + 0] & 0xFF;

    42         k |= (data[i + 1] & 0xFF) << 8;

    43         k |= (data[i + 2] & 0xFF) << 16;

    44         k |= (data[i + 3] & 0xFF) << 24;

    46         k *= m;

    47         k ^= k >> r;

    48         k *= m;

    50         h *= m;

    51         h ^= k;

    53         i += 4;

    54         len -= 4;

    55     }

    57     switch (len) {

    58         case 3:

    59             h ^= (data[i + 2] & 0xFF) << 16;

    60                     __attribute__((__fallthrough__));

    61         case 2:

    62             h ^= (data[i + 1] & 0xFF) << 8;

    63                     __attribute__((__fallthrough__));

    64         case 1:

    65             h ^= (data[i + 0] & 0xFF);

    66             h *= m;

    67                     __attribute__((__fallthrough__));

    68         default:

    69             /* do nothing */;

    70     }

    72     h ^= h >> 13;

    73     h *= m;

    74     h ^= h >> 15;

    76     key->hash = h;

    77 }

    79 CxHashKey cx_hash_key_str(char const *str) {

    80     CxHashKey key;

    81     key.data.cstr = str;

    82     key.len = str == NULL ? 0 : (1 + strlen(str));

    83     cx_hash_murmur(&key);

    84     return key;

    85 }

    87 CxHashKey cx_hash_key_bytes(

    88         unsigned char const *bytes,

    89         size_t len

    90 ) {

    91     CxHashKey key;

    92     key.data.cbytes = bytes;

    93     key.len = len;

    94     cx_hash_murmur(&key);

    95     return key;

    96 }

    98 CxHashKey cx_hash_key(

    99         void *obj,

   100         size_t len

   101 ) {

   102     CxHashKey key;

   103     key.data.obj = obj;

   104     key.len = len;

   105     cx_hash_murmur(&key);

   106     return key;

   107 }

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