55 lines
1.6 KiB
C
55 lines
1.6 KiB
C
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/**
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* Copyright (c) 2014-2018 Enzien Audio Ltd.
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*
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* Permission to use, copy, modify, and/or distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
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* REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
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* AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
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* INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
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* LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
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* OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
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* PERFORMANCE OF THIS SOFTWARE.
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*/
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#include "HvUtils.h"
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hv_uint32_t hv_string_to_hash(const char *str) {
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// this hash is based MurmurHash2
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// http://en.wikipedia.org/wiki/MurmurHash
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// https://sites.google.com/site/murmurhash/
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static const hv_uint32_t n = 0x5bd1e995;
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static const hv_int32_t r = 24;
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if (str == NULL) return 0;
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hv_uint32_t len = (hv_uint32_t) hv_strlen(str);
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hv_uint32_t x = len; // seed (0) ^ len
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while (len >= 4) {
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#if HV_EMSCRIPTEN
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hv_uint32_t k = str[0] | (str[1] << 8) | (str[2] << 16) | (str[3] << 24);
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#else
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hv_uint32_t k = *((hv_uint32_t *) str);
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#endif
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k *= n;
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k ^= (k >> r);
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k *= n;
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x *= n;
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x ^= k;
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str += 4; len -= 4;
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}
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switch (len) {
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case 3: x ^= (str[2] << 16);
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case 2: x ^= (str[1] << 8);
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case 1: x ^= str[0]; x *= n;
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default: break;
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}
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x ^= (x >> 13);
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x *= n;
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x ^= (x >> 15);
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return x;
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}
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