/* * fnv - Fowler/Noll/Vo- hash code * * @(#) $Revision$ * @(#) $Id$ * @(#) $Source$ * *** * * 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://reality.sgi.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 architected 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://reality.sgi.com/chongo/tech/comp/fnv/ * * 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(). * *** * * 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://reality.sgi.com/chongo/ * EMail: chongo_fnv at prime dot engr dot sgi dot com * * 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 inital basis instead. */ #define FNV0_32_INIT ((Fnv32_t)0) /* * 32 bit FNV-1 non-zero initial basis * * The FNV-1 initial basis is the FNV-0 hash of the following 32 octets: * * chongo /\../\ * * Note that the \'s above are not back-slashing escape characters. * They are literal ASCII backslash 0x5c characters. */ #define FNV1_32_INIT ((Fnv32_t)0x811c9dc5) Fnv32_t fnv_32_buf(void *, size_t, Fnv32_t); Fnv32_t fnv_32_str(char *, Fnv32_t ); unsigned long FnvHash(char *); #endif /* __FNV_H__ */