76 lines
2.3 KiB
C++
76 lines
2.3 KiB
C++
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/*
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Porting - 2014 Alex K
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Algorithm (c) Paul Hsieh http://www.azillionmonkeys.com/qed/hash.html
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The latest version of this library may be found at:
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https://github.com/mrbio/Arduino-rokkit-hash
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Permission is hereby granted, free of charge, to any person obtaining
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a copy of this software and associated documentation files (the
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"Software"), to deal in the Software without restriction, including
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without limitation the rights to use, copy, modify, merge, publish,
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distribute, sublicense, and/or sell copies of the Software, and to
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permit persons to whom the Software is furnished to do so, subject to
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the following conditions:
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The above copyright notice and this permission notice shall be
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included in all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
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LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
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OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
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WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/
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#include <inttypes.h>
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uint32_t rokkit(const char * data, int len) {
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uint32_t hash, tmp;
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int rem;
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if (len <= 0 || data == 0) return 0;
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hash = len;
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rem = len & 3;
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len >>= 2;
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/* Main loop */
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while (len > 0) {
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hash += *((uint16_t*)data);
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tmp = (*((uint16_t*)(data+2)) << 11) ^ hash;
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hash = (hash << 16) ^ tmp;
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data += 2*2;
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hash += hash >> 11;
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len--;
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}
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/* Handle end cases */
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switch (rem) {
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case 3: hash += *((uint16_t*)data);
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hash ^= hash << 16;
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hash ^= ((signed char)data[2]) << 18;
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hash += hash >> 11;
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break;
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case 2: hash += *((uint16_t*)data);
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hash ^= hash << 11;
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hash += hash >> 17;
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break;
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case 1: hash += (signed char)*data;
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hash ^= hash << 10;
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hash += hash >> 1;
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}
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/* Force "avalanching" of final 127 bits */
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hash ^= hash << 3;
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hash += hash >> 5;
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hash ^= hash << 4;
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hash += hash >> 17;
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hash ^= hash << 25;
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hash += hash >> 6;
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return hash;
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}
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