Python库 | fnvhash2-0.1.3.tar.gz

/* * hash_64 - 64 bit Fowler/Noll/Vo-0 hash code * * @(#) $Revision: 5.1 $ * @(#) $Id: hash_64.c,v 5.1 2009/06/30 09:01:38 chongo Exp $ * @(#) $Source: /usr/local/src/cmd/fnv/RCS/hash_64.c,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 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 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 <Landon Curt Noll> /\oo/\ * http://www.isthe.com/chongo/ * * Share and Enjoy! :-) */ #include <stdlib.h> #include "fnv.h" /* * FNV-0 defines the initial basis to be zero */ #if !defined(HAVE_64BIT_LONG_LONG) const Fnv64_t fnv0_64_init = { 0UL, 0UL }; #endif /* ! HAVE_64BIT_LONG_LONG */ /* * FNV-1 defines the initial basis to be non-zero */ #if !defined(HAVE_64BIT_LONG_LONG) const Fnv64_t fnv1_64_init = { 0x84222325UL, 0xcbf29ce4UL }; #endif /* ! HAVE_64BIT_LONG_LONG */ /* * 64 bit magic FNV-0 and FNV-1 prime */ #if defined(HAVE_64BIT_LONG_LONG) #define FNV_64_PRIME ((Fnv64_t)0x100000001b3ULL) #else /* HAVE_64BIT_LONG_LONG */ #define FNV_64_PRIME_LOW ((unsigned long)0x1b3) /* lower bits of FNV prime */ #define FNV_64_PRIME_SHIFT (8) /* top FNV prime shift above 2^32 */ #endif /* HAVE_64BIT_LONG_LONG */ /* * fnv_64_buf - perform a 64 bit Fowler/Noll/Vo hash on a buffer * * input: * buf - start of buffer to hash * len - length of buffer in octets * hval - previous hash value or 0 if first call * * returns: * 64 bit hash as a static hash type * * NOTE: To use the 64 bit FNV-0 historic hash, use FNV0_64_INIT as the hval * argument on the first call to either fnv_64_buf() or fnv_64_str(). * * NOTE: To use the recommended 64 bit FNV-1 hash, use FNV1_64_INIT as the hval * argument on the first call to either fnv_64_buf() or fnv_64_str(). */ Fnv64_t fnv_64_buf(void *buf, size_t len, Fnv64_t hval) { unsigned char *bp = (unsigned char *)buf; /* start of buffer */ unsigned char *be = bp + len; /* beyond end of buffer */ #if defined(HAVE_64BIT_LONG_LONG) /* * FNV-1 hash each octet of the buffer */ while (bp < be) { /* multiply by the 64 bit FNV magic prime mod 2^64 */ #if defined(NO_FNV_GCC_OPTIMIZATION) hval *= FNV_64_PRIME; #else /* NO_FNV_GCC_OPTIMIZATION */ hval += (hval << 1) + (hval << 4) + (hval << 5) + (hval << 7) + (hval << 8) + (hval << 40); #endif /* NO_FNV_GCC_OPTIMIZATION */ /* xor the bottom with the current octet */ hval ^= (Fnv64_t)*bp++; } #else /* HAVE_64BIT_LONG_LONG */ unsigned long val[4]; /* hash value in base 2^16 */ unsigned long tmp[4]; /* tmp 64 bit value */ /* * Convert Fnv64_t hval into a base 2^16 array */ val[0] = hval.w32[0]; val[1] = (val[0] >> 16); val[0] &= 0xffff; val[2] = hval.w32[1]; val[3] = (val[2] >> 16); val[2] &= 0xffff; /* * FNV-1 hash each octet of the buffer */ while (bp < be) { /* * multiply by the 64 bit FNV magic prime mod 2^64 * * Using 0x100000001b3 we have the following digits base 2^16: * * 0x0 0x100 0x0 0x1b3 * * which is the same as: * * 0x0 1<<FNV_64_PRIME_SHIFT 0x0 FNV_64_PRIME_LOW */ /* multiply by the lowest order digit base 2^16 */ tmp[0] = val[0] * FNV_64_PRIME_LOW; tmp[1] = val[1] * FNV_64_PRIME_LOW; tmp[2] = val[2] * FNV_64_PRIME_LOW; tmp[3] = val[3] * FNV_64_PRIME_LOW; /* multiply by the other non-zero digit */ tmp[2] += val[0] << FNV_64_PRIME_SHIFT; /* tmp[2] += val[0] * 0x100 */ tmp[3] += val[1] << FNV_64_PRIME_SHIFT; /* tmp[3] += val[1] * 0x100 */ /* propagate carries */ tmp[1] += (tmp[0] >> 16); val[0] = tmp[0] & 0xffff; tmp[2] += (tmp[1] >> 16); val[1] = tmp[1] & 0xffff; val[3] = tmp[3] + (tmp[2] >> 16); val[2] = tmp[2] & 0xffff; /* * Doing a val[3] &= 0xffff; is not really needed since it simply * removes multiples of 2^64. We can discard these excess bits * outside of the loop when we convert to Fnv64_t. */ /* xor the bottom with the current octet */ val[0] ^= (unsigned long)*bp++; } /* * Convert base 2^16 array back into an Fnv64_t */ hval.w32[1] = ((val[3]<<16) | val[2]); hval.w32[0] = ((val[1]<<16) | val[0]); #endif /* HAVE_64BIT_LONG_LONG */ /* return our new hash value */ return hval; } /* * fnv_64_str - perform a 64 bit Fowler/Noll/Vo hash on a buffer * * input: * buf - start of buffer to hash * hval - previous hash value or 0 if first call * * returns: * 64 bit hash as a static hash type * * NOTE: To use the 64 bit FNV-0 historic hash, use FNV0_64_INIT as the hval * argument on the first call to either fnv_64_buf() or fnv_64_str(). * * NOTE: To use the recommended 64 bit FNV-1 hash, use FNV1_64_INIT as the hval * argument on the first call to either fnv_64_buf() or fnv_64_str(). */ Fnv64_t fnv_64_str(char *str, Fnv64_t hval) { unsigned char *s = (unsigned char *)str; /* unsigned string */ #if defined(HAVE_64BIT_LONG_LONG) /* * FNV-1 hash each octet of the string */ while (*s) { /* multiply by the 64 bit FNV magic prime mod 2^64 */ #if defined(NO_FNV_GCC_OPTIMIZATION) hval *= FNV_64_PRIME; #else /* NO_FNV_GCC_OPTIMIZATION */ hval += (hval << 1) + (hval << 4) + (hval << 5) + (hval << 7) + (hval << 8) + (hval << 40); #endif /* NO_FNV_GCC_OPTIMIZATION */ /* xor the bottom with the current octet */ hval ^= (Fnv64_t)*s++; } #else /* !HAVE_64BIT_LONG_LONG */ unsigned long val[4]; /* hash value in base 2^16 */ unsigned long tmp[4]; /* tmp 64 bit value */ /* * Convert Fnv64_t hval into a base 2^16 array */ val[0] = hval.w32[0]; val[1] = (val[0] >> 16); val[0] &= 0xffff; val[2] = hval.w32[1]; val[3] = (val[2] >> 16); val[2] &= 0xffff; /* * FNV-1 hash each octet of the string */ while (*s) { /* * multiply by the 64 bit FNV magic prime mod 2^64 * * Using 1099511628211, we have the following digits base 2^16: * * 0x0 0x100 0x0 0x1b3 * * which is the same as: * * 0x0 1<<FNV_64_PRIME_SHIFT 0x0 FNV_64_PRIME_LOW */ /* multiply by the lowest order digit base 2^16 */ tmp[0] = val[0] * FNV_64_PRIME_LOW; tmp[1] = val[1] * FNV_64_PRIME_LOW; tmp[2] = val[2] * FNV_64_PRIME_LOW; tmp[3] = val[3] * FNV_64_PRIME_LOW; /* multiply by the other non-zero digit */ tmp[2] += val[0] << FNV_64_PRIME_SHIFT; /* tmp[2] += val[0] * 0x1