/* * fnv - Fowler/Noll/Vo- hash code * * @(#) $Revision: 5.4 $ * @(#) $Id: fnv.h,v 5.4 2009/07/30 22:49:13 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 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 32 bit FNV-1a hash, pass FNV1_32A_INIT as the * Fnv32_t hashval argument to fnv_32a_buf() or fnv_32a_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 /\oo/\ * http://www.isthe.com/chongo/ * * Share and Enjoy! :-) */ #if !defined(__FNV_H__) #define __FNV_H__ #include #define FNV_VERSION "5.0.2" /* @(#) FNV Version */ /* * 32 bit FNV-0 hash type */ typedef uint32_t Fnv32_t; /* * 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 /\../\ * * 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 extern Fnv32_t fnv_32a_buf(const void *buf, size_t len, Fnv32_t hashval); extern Fnv32_t fnv_32a_str(const char *buf, Fnv32_t hashval); #endif /* __FNV_H__ */