Alex 'AdUser' Z
4 years ago
13 changed files with 284 additions and 28 deletions
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/*
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* fnv - Fowler/Noll/Vo- hash code |
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* |
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* @(#) $Revision: 5.4 $ |
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* @(#) $Id: fnv.h,v 5.4 2009/07/30 22:49:13 chongo Exp $ |
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* @(#) $Source: /usr/local/src/cmd/fnv/RCS/fnv.h,v $ |
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* |
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*** |
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* |
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* Fowler/Noll/Vo- hash |
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* |
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* The basis of this hash algorithm was taken from an idea sent |
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* as reviewer comments to the IEEE POSIX P1003.2 committee by: |
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* |
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* Phong Vo (http://www.research.att.com/info/kpv/)
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* Glenn Fowler (http://www.research.att.com/~gsf/)
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* |
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* In a subsequent ballot round: |
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* |
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* Landon Curt Noll (http://www.isthe.com/chongo/)
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* |
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* improved on their algorithm. Some people tried this hash |
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* and found that it worked rather well. In an EMail message |
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* to Landon, they named it the ``Fowler/Noll/Vo'' or FNV hash. |
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* |
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* FNV hashes are designed to be fast while maintaining a low |
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* collision rate. The FNV speed allows one to quickly hash lots |
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* of data while maintaining a reasonable collision rate. See: |
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* |
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* http://www.isthe.com/chongo/tech/comp/fnv/index.html
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* |
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* for more details as well as other forms of the FNV hash. |
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* |
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*** |
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* |
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* NOTE: The FNV-0 historic hash is not recommended. One should use |
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* the FNV-1 hash instead. |
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* |
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* To use the 32 bit FNV-0 historic hash, pass FNV0_32_INIT as the |
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* Fnv32_t hashval argument to fnv_32_buf() or fnv_32_str(). |
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* |
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* To use the recommended 32 bit FNV-1 hash, pass FNV1_32_INIT as the |
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* Fnv32_t hashval argument to fnv_32_buf() or fnv_32_str(). |
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* |
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* To use the recommended 32 bit FNV-1a hash, pass FNV1_32A_INIT as the |
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* Fnv32_t hashval argument to fnv_32a_buf() or fnv_32a_str(). |
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* |
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*** |
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* |
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* Please do not copyright this code. This code is in the public domain. |
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* |
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* LANDON CURT NOLL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, |
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* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO |
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* EVENT SHALL LANDON CURT NOLL BE LIABLE FOR ANY SPECIAL, INDIRECT OR |
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* CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF |
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* 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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* By: |
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* chongo <Landon Curt Noll> /\oo/\
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* http://www.isthe.com/chongo/
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* |
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* Share and Enjoy! :-) |
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*/ |
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#if !defined(__FNV_H__) |
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#define __FNV_H__ |
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#include <sys/types.h> |
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#define FNV_VERSION "5.0.2" /* @(#) FNV Version */ |
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/*
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* 32 bit FNV-0 hash type |
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*/ |
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typedef uint32_t Fnv32_t; |
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/*
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* 32 bit FNV-1 and FNV-1a non-zero initial basis |
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* |
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* The FNV-1 initial basis is the FNV-0 hash of the following 32 octets: |
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* |
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* chongo <Landon Curt Noll> /\../\
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* |
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* NOTE: The \'s above are not back-slashing escape characters. |
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* They are literal ASCII backslash 0x5c characters. |
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* |
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* NOTE: The FNV-1a initial basis is the same value as FNV-1 by definition. |
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*/ |
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#define FNV1_32_INIT ((Fnv32_t)0x811c9dc5) |
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#define FNV1_32A_INIT FNV1_32_INIT |
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extern Fnv32_t fnv_32a_buf(const void *buf, size_t len, Fnv32_t hashval); |
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extern Fnv32_t fnv_32a_str(const char *buf, Fnv32_t hashval); |
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#endif /* __FNV_H__ */ |
@ -0,0 +1,142 @@ |
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/*
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* hash_32 - 32 bit Fowler/Noll/Vo FNV-1a hash code |
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* |
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* @(#) $Revision: 5.1 $ |
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* @(#) $Id: hash_32a.c,v 5.1 2009/06/30 09:13:32 chongo Exp $ |
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* @(#) $Source: /usr/local/src/cmd/fnv/RCS/hash_32a.c,v $ |
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* |
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*** |
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* |
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* Fowler/Noll/Vo hash |
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* |
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* The basis of this hash algorithm was taken from an idea sent |
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* as reviewer comments to the IEEE POSIX P1003.2 committee by: |
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* |
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* Phong Vo (http://www.research.att.com/info/kpv/)
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* Glenn Fowler (http://www.research.att.com/~gsf/)
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* |
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* In a subsequent ballot round: |
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* |
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* Landon Curt Noll (http://www.isthe.com/chongo/)
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* |
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* improved on their algorithm. Some people tried this hash |
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* and found that it worked rather well. In an EMail message |
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* to Landon, they named it the ``Fowler/Noll/Vo'' or FNV hash. |
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* |
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* FNV hashes are designed to be fast while maintaining a low |
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* collision rate. The FNV speed allows one to quickly hash lots |
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* of data while maintaining a reasonable collision rate. See: |
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* |
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* http://www.isthe.com/chongo/tech/comp/fnv/index.html
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* |
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* for more details as well as other forms of the FNV hash. |
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*** |
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* |
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* To use the recommended 32 bit FNV-1a hash, pass FNV1_32A_INIT as the |
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* Fnv32_t hashval argument to fnv_32a_buf() or fnv_32a_str(). |
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* |
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*** |
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* |
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* Please do not copyright this code. This code is in the public domain. |
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* |
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* LANDON CURT NOLL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, |
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* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO |
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* EVENT SHALL LANDON CURT NOLL BE LIABLE FOR ANY SPECIAL, INDIRECT OR |
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* CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF |
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* 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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* By: |
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* chongo <Landon Curt Noll> /\oo/\
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* http://www.isthe.com/chongo/
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* |
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* Share and Enjoy! :-) |
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*/ |
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#include <stdlib.h> |
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#include <stdint.h> |
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#include "fnv.h" |
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/*
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* 32 bit magic FNV-1a prime |
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*/ |
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#define FNV_32_PRIME ((Fnv32_t)0x01000193) |
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/*
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* fnv_32a_buf - perform a 32 bit Fowler/Noll/Vo FNV-1a hash on a buffer |
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* |
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* input: |
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* buf - start of buffer to hash |
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* len - length of buffer in octets |
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* hval - previous hash value or 0 if first call |
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* |
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* returns: |
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* 32 bit hash as a static hash type |
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* |
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* NOTE: To use the recommended 32 bit FNV-1a hash, use FNV1_32A_INIT as the |
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* hval arg on the first call to either fnv_32a_buf() or fnv_32a_str(). |
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*/ |
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Fnv32_t |
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fnv_32a_buf(const void *buf, size_t len, Fnv32_t hval) |
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{ |
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unsigned char *bp = (unsigned char *)buf; /* start of buffer */ |
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unsigned char *be = bp + len; /* beyond end of buffer */ |
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/*
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* FNV-1a hash each octet in the buffer |
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*/ |
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while (bp < be) { |
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/* xor the bottom with the current octet */ |
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hval ^= (Fnv32_t)*bp++; |
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/* multiply by the 32 bit FNV magic prime mod 2^32 */ |
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#if defined(NO_FNV_GCC_OPTIMIZATION) |
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hval *= FNV_32_PRIME; |
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#else |
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hval += (hval<<1) + (hval<<4) + (hval<<7) + (hval<<8) + (hval<<24); |
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#endif |
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} |
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/* return our new hash value */ |
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return hval; |
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} |
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/*
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* fnv_32a_str - perform a 32 bit Fowler/Noll/Vo FNV-1a hash on a string |
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* |
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* input: |
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* str - string to hash |
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* hval - previous hash value or 0 if first call |
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* |
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* returns: |
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* 32 bit hash as a static hash type |
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* |
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* NOTE: To use the recommended 32 bit FNV-1a hash, use FNV1_32A_INIT as the |
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* hval arg on the first call to either fnv_32a_buf() or fnv_32a_str(). |
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*/ |
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Fnv32_t |
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fnv_32a_str(const char *str, Fnv32_t hval) |
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{ |
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unsigned char *s = (unsigned char *)str; /* unsigned string */ |
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/*
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* FNV-1a hash each octet in the buffer |
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*/ |
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while (*s) { |
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/* xor the bottom with the current octet */ |
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hval ^= (Fnv32_t)*s++; |
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/* multiply by the 32 bit FNV magic prime mod 2^32 */ |
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#if defined(NO_FNV_GCC_OPTIMIZATION) |
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hval *= FNV_32_PRIME; |
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#else |
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hval += (hval<<1) + (hval<<4) + (hval<<7) + (hval<<8) + (hval<<24); |
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#endif |
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} |
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/* return our new hash value */ |
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return hval; |
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} |
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