diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/README | 4 | ||||
| -rw-r--r-- | lib/fast-hash/fasthash.c | 75 | ||||
| -rw-r--r-- | lib/fast-hash/fasthash.h | 56 |
3 files changed, 135 insertions, 0 deletions
@@ -74,3 +74,7 @@ revision 425a42d82006cf0aa24be27b483d2f6a41607489. The code is taken from the repo's hc-sr04-range-sensor directory. It has been modified so that the IEP definitions compile correctly. See pru_rpmsg.patch for the modifications. + +The fast-hash directory contains code from: + https://github.com/ztanml/fast-hash +revision ae3bb53c199fe75619e940b5b6a3584ede99c5fc
\ No newline at end of file diff --git a/lib/fast-hash/fasthash.c b/lib/fast-hash/fasthash.c new file mode 100644 index 00000000..48e16ce5 --- /dev/null +++ b/lib/fast-hash/fasthash.c @@ -0,0 +1,75 @@ +/* The MIT License + + Copyright (C) 2012 Zilong Tan (eric.zltan@gmail.com) + + Permission is hereby granted, free of charge, to any person + obtaining a copy of this software and associated documentation + files (the "Software"), to deal in the Software without + restriction, including without limitation the rights to use, copy, + modify, merge, publish, distribute, sublicense, and/or sell copies + of the Software, and to permit persons to whom the Software is + furnished to do so, subject to the following conditions: + + The above copyright notice and this permission notice shall be + included in all copies or substantial portions of the Software. + + THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, + EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF + MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND + NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS + BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN + ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN + CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE + SOFTWARE. +*/ + +#include "fasthash.h" + +// Compression function for Merkle-Damgard construction. +// This function is generated using the framework provided. +#define mix(h) ({ \ + (h) ^= (h) >> 23; \ + (h) *= 0x2127599bf4325c37ULL; \ + (h) ^= (h) >> 47; }) + +uint64_t fasthash64(const void *buf, size_t len, uint64_t seed) +{ + const uint64_t m = 0x880355f21e6d1965ULL; + const uint64_t *pos = (const uint64_t *)buf; + const uint64_t *end = pos + (len / 8); + const unsigned char *pos2; + uint64_t h = seed ^ (len * m); + uint64_t v; + + while (pos != end) { + v = *pos++; + h ^= mix(v); + h *= m; + } + + pos2 = (const unsigned char*)pos; + v = 0; + + switch (len & 7) { + case 7: v ^= (uint64_t)pos2[6] << 48; + case 6: v ^= (uint64_t)pos2[5] << 40; + case 5: v ^= (uint64_t)pos2[4] << 32; + case 4: v ^= (uint64_t)pos2[3] << 24; + case 3: v ^= (uint64_t)pos2[2] << 16; + case 2: v ^= (uint64_t)pos2[1] << 8; + case 1: v ^= (uint64_t)pos2[0]; + h ^= mix(v); + h *= m; + } + + return mix(h); +} + +uint32_t fasthash32(const void *buf, size_t len, uint32_t seed) +{ + // the following trick converts the 64-bit hashcode to Fermat + // residue, which shall retain information from both the higher + // and lower parts of hashcode. + uint64_t h = fasthash64(buf, len, seed); + return h - (h >> 32); +} diff --git a/lib/fast-hash/fasthash.h b/lib/fast-hash/fasthash.h new file mode 100644 index 00000000..15ac2222 --- /dev/null +++ b/lib/fast-hash/fasthash.h @@ -0,0 +1,56 @@ +/* The MIT License + + Copyright (C) 2012 Zilong Tan (eric.zltan@gmail.com) + + Permission is hereby granted, free of charge, to any person + obtaining a copy of this software and associated documentation + files (the "Software"), to deal in the Software without + restriction, including without limitation the rights to use, copy, + modify, merge, publish, distribute, sublicense, and/or sell copies + of the Software, and to permit persons to whom the Software is + furnished to do so, subject to the following conditions: + + The above copyright notice and this permission notice shall be + included in all copies or substantial portions of the Software. + + THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, + EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF + MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND + NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS + BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN + ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN + CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE + SOFTWARE. +*/ + +#ifndef _FASTHASH_H +#define _FASTHASH_H + +#include <stdint.h> +#include <stdio.h> + +#ifdef __cplusplus +extern "C" { +#endif + +/** + * fasthash32 - 32-bit implementation of fasthash + * @buf: data buffer + * @len: data size + * @seed: the seed + */ + uint32_t fasthash32(const void *buf, size_t len, uint32_t seed); + +/** + * fasthash64 - 64-bit implementation of fasthash + * @buf: data buffer + * @len: data size + * @seed: the seed + */ + uint64_t fasthash64(const void *buf, size_t len, uint64_t seed); + +#ifdef __cplusplus +} +#endif + +#endif |