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98 lines
3.0 KiB
98 lines
3.0 KiB
4 years ago
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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__ */
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