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fnv_hash.h
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1 /* Copyright (c) 2010 Wildfire Games
2  *
3  * Permission is hereby granted, free of charge, to any person obtaining
4  * a copy of this software and associated documentation files (the
5  * "Software"), to deal in the Software without restriction, including
6  * without limitation the rights to use, copy, modify, merge, publish,
7  * distribute, sublicense, and/or sell copies of the Software, and to
8  * permit persons to whom the Software is furnished to do so, subject to
9  * the following conditions:
10  *
11  * The above copyright notice and this permission notice shall be included
12  * in all copies or substantial portions of the Software.
13  *
14  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
15  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
16  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
17  * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
18  * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
19  * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
20  * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
21  */
22 
23 /*
24  * Fowler/Noll/Vo string hash
25  */
26 
27 #ifndef INCLUDED_FNV_HASH
28 #define INCLUDED_FNV_HASH
29 
30 /**
31  * rationale: this algorithm was chosen because it delivers 'good' results
32  * for string data and is relatively simple. other good alternatives exist;
33  * see Ozan Yigit's hash roundup.
34  **/
35 
36 /**
37  * calculate FNV1-A hash.
38  *
39  * @param buf input buffer.
40  * @param len if 0 (default), treat buf as a C-string; otherwise,
41  * indicates how many bytes of buffer to hash.
42  * @return hash result. note: results are distinct for buffers containing
43  * differing amounts of zero bytes because the hash value is seeded.
44  **/
45 extern u32 fnv_hash(const void* buf, size_t len = 0);
46 /// 64-bit version of fnv_hash.
47 extern u64 fnv_hash64(const void* buf, size_t len = 0);
48 
49 /**
50  * special version of fnv_hash for strings: first converts to lowercase
51  * (useful for comparing mixed-case filenames)
52  **/
53 extern u32 fnv_lc_hash(const char* str, size_t len = 0);
54 
55 #endif // #ifndef INCLUDED_FNV_HASH
u32 fnv_hash(const void *buf, size_t len=0)
rationale: this algorithm was chosen because it delivers 'good' results for string data and is relati...
Definition: fnv_hash.cpp:33
u64 fnv_hash64(const void *buf, size_t len=0)
64-bit version of fnv_hash.
Definition: fnv_hash.cpp:69
uint64_t u64
Definition: types.h:40
uint32_t u32
Definition: types.h:39
u32 fnv_lc_hash(const char *str, size_t len=0)
special version of fnv_hash for strings: first converts to lowercase (useful for comparing mixed-case...
Definition: fnv_hash.cpp:105