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Hash_fnv.h
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Hash_fnv.h
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/*
* fnv - Fowler/Noll/Vo- hash code
*
* @(#) $Revision: 1.5 $
* @(#) $Id: fnv.h,v 1.5 2003/10/03 20:35:52 chongo Exp $
* @(#) $Source: /usr/local/src/cmd/fnv/RCS/fnv.h,v $
*
***
*
* Fowler/Noll/Vo- hash
*
* The basis of this hash algorithm was taken from an idea sent
* as reviewer comments to the IEEE POSIX P1003.2 committee by:
*
* Phong Vo (http://www.research.att.com/info/kpv/)
* Glenn Fowler (http://www.research.att.com/~gsf/)
*
* In a subsequent ballot round:
*
* Landon Curt Noll (http://www.isthe.com/chongo/)
*
* improved on their algorithm. Some people tried this hash
* and found that it worked rather well. In an EMail message
* to Landon, they named it the ``Fowler/Noll/Vo'' or FNV hash.
*
* FNV hashes are designed to be fast while maintaining a low
* collision rate. The FNV speed allows one to quickly hash lots
* of data while maintaining a reasonable collision rate. See:
*
* http://www.isthe.com/chongo/tech/comp/fnv/index.html
*
* for more details as well as other forms of the FNV hash.
*
***
*
* NOTE: The FNV-0 historic hash is not recommended. One should use
* the FNV-1 hash instead.
*
* To use the 32 bit FNV-0 historic hash, pass FNV0_32_INIT as the
* Fnv32_t hashval argument to fnv_32_buf() or fnv_32_str().
*
* To use the 64 bit FNV-0 historic hash, pass FNV0_64_INIT as the
* Fnv64_t hashval argument to fnv_64_buf() or fnv_64_str().
*
* To use the recommended 32 bit FNV-1 hash, pass FNV1_32_INIT as the
* Fnv32_t hashval argument to fnv_32_buf() or fnv_32_str().
*
* To use the recommended 64 bit FNV-1 hash, pass FNV1_64_INIT as the
* Fnv64_t hashval argument to fnv_64_buf() or fnv_64_str().
*
* To use the recommended 32 bit FNV-1a hash, pass FNV1_32A_INIT as the
* Fnv32_t hashval argument to fnv_32a_buf() or fnv_32a_str().
*
* To use the recommended 64 bit FNV-1a hash, pass FNV1_64A_INIT as the
* Fnv64_t hashval argument to fnv_64a_buf() or fnv_64a_str().
*
***
*
* Please do not copyright this code. This code is in the public domain.
*
* LANDON CURT NOLL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO
* EVENT SHALL LANDON CURT NOLL BE LIABLE FOR ANY SPECIAL, INDIRECT OR
* CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF
* USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
* OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
* PERFORMANCE OF THIS SOFTWARE.
*
* By:
* chongo <Landon Curt Noll> /\oo/\
* http://www.isthe.com/chongo/
*
* Share and Enjoy! :-)
*/
#if !defined(__FNV_H__)
#define __FNV_H__
/*
* 32 bit FNV-0 hash type
*/
typedef unsigned long Fnv32_t;
/*
* 32 bit FNV-0 zero initial basis
*
* This historic hash is not recommended. One should use
* the FNV-1 hash and initial basis instead.
*/
#define FNV0_32_INIT ((Fnv32_t)0)
/*
* 32 bit FNV-1 and FNV-1a non-zero initial basis
*
* The FNV-1 initial basis is the FNV-0 hash of the following 32 octets:
*
* chongo <Landon Curt Noll> /\../\
*
* NOTE: The \'s above are not back-slashing escape characters.
* They are literal ASCII backslash 0x5c characters.
*
* NOTE: The FNV-1a initial basis is the same value as FNV-1 by definition.
*/
#define FNV1_32_INIT ((Fnv32_t)0x811c9dc5)
#define FNV1_32A_INIT FNV1_32_INIT
/*
* determine how 64 bit unsigned values are represented
*/
//#include "longlong.h"
/*
* 64 bit FNV-0 hash
*/
#if defined(HAVE_64BIT_LONG_LONG)
typedef unsigned long long Fnv64_t;
#else
typedef struct {
unsigned long w32[2];
} Fnv64_t;
#endif
/*
* 64 bit FNV-0 zero initial basis
*
* This historic hash is not recommended. One should use
* the FNV-1 hash and initial basis instead.
*/
#if defined(HAVE_64BIT_LONG_LONG)
#define FNV0_64_INIT ((Fnv64_t)0)
#else
extern const Fnv64_t fnv1_64_init;
#define FNV0_64_INIT (fnv1_64_init)
#endif
/*
* 64 bit FNV-1 non-zero initial basis
*
* The FNV-1 initial basis is the FNV-0 hash of the following 32 octets:
*
* chongo <Landon Curt Noll> /\../\
*
* NOTE: The \'s above are not back-slashing escape characters.
* They are literal ASCII backslash 0x5c characters.
*
* NOTE: The FNV-1a initial basis is the same value as FNV-1 by definition.
*/
#if defined(HAVE_64BIT_LONG_LONG)
#define FNV1_64_INIT ((Fnv64_t)0xcbf29ce484222325ULL)
#define FNV1_64A_INIT FNV1_64_INIT
#else
extern const Fnv64_t fnv1_64_init;
extern const Fnv64_t fnv1_64a_init;
#define FNV1_64_INIT (fnv1_64_init)
#define FNV1_64A_INIT FNV1_64_INIT
#endif
/*
* external functions
*/
extern Fnv32_t fnv_32_buf(void *buf, size_t len, Fnv32_t hashval);
extern Fnv32_t fnv_32_str(char *buf, Fnv32_t hashval);
extern Fnv64_t fnv_64_buf(void *buf, size_t len, Fnv64_t hashval);
extern Fnv64_t fnv_64_str(char *buf, Fnv64_t hashval);
extern Fnv32_t fnv_32a_buf(void *buf, size_t len, Fnv32_t hashval);
extern Fnv32_t fnv_32a_str(char *buf, Fnv32_t hashval);
extern Fnv64_t fnv_64a_buf(void *buf, size_t len, Fnv64_t hashval);
extern Fnv64_t fnv_64a_str(char *buf, Fnv64_t hashval);
#endif /* __FNV_H__ */