01ecf332ff
* Initial import of wear-leveling algorithm. * Alignment. * Docs tweaks. * Lock/unlock. * Update quantum/wear_leveling/wear_leveling_internal.h Co-authored-by: Stefan Kerkmann <karlk90@pm.me> * More tests, fix issue with consolidation when unlocked. * More tests. * Review comments. * Add plumbing for FNV1a. * Another test checking that checksum mismatch clears the cache. * Check that the write log still gets played back. Co-authored-by: Stefan Kerkmann <karlk90@pm.me>
156 lines
4.4 KiB
C
156 lines
4.4 KiB
C
/*
|
|
* hash_32 - 32 bit Fowler/Noll/Vo hash code
|
|
*
|
|
* @(#) $Revision: 5.1 $
|
|
* @(#) $Id: hash_32.c,v 5.1 2009/06/30 09:13:32 chongo Exp $
|
|
* @(#) $Source: /usr/local/src/cmd/fnv/RCS/hash_32.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 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().
|
|
*
|
|
***
|
|
*
|
|
* 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"
|
|
|
|
|
|
/*
|
|
* 32 bit magic FNV-0 and FNV-1 prime
|
|
*/
|
|
#define FNV_32_PRIME ((Fnv32_t)0x01000193)
|
|
|
|
|
|
/*
|
|
* fnv_32_buf - perform a 32 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:
|
|
* 32 bit hash as a static hash type
|
|
*
|
|
* NOTE: To use the 32 bit FNV-0 historic hash, use FNV0_32_INIT as the hval
|
|
* argument on the first call to either fnv_32_buf() or fnv_32_str().
|
|
*
|
|
* NOTE: To use the recommended 32 bit FNV-1 hash, use FNV1_32_INIT as the hval
|
|
* argument on the first call to either fnv_32_buf() or fnv_32_str().
|
|
*/
|
|
Fnv32_t
|
|
fnv_32_buf(void *buf, size_t len, Fnv32_t hval)
|
|
{
|
|
unsigned char *bp = (unsigned char *)buf; /* start of buffer */
|
|
unsigned char *be = bp + len; /* beyond end of buffer */
|
|
|
|
/*
|
|
* FNV-1 hash each octet in the buffer
|
|
*/
|
|
while (bp < be) {
|
|
|
|
/* multiply by the 32 bit FNV magic prime mod 2^32 */
|
|
#if defined(NO_FNV_GCC_OPTIMIZATION)
|
|
hval *= FNV_32_PRIME;
|
|
#else
|
|
hval += (hval<<1) + (hval<<4) + (hval<<7) + (hval<<8) + (hval<<24);
|
|
#endif
|
|
|
|
/* xor the bottom with the current octet */
|
|
hval ^= (Fnv32_t)*bp++;
|
|
}
|
|
|
|
/* return our new hash value */
|
|
return hval;
|
|
}
|
|
|
|
|
|
/*
|
|
* fnv_32_str - perform a 32 bit Fowler/Noll/Vo hash on a string
|
|
*
|
|
* input:
|
|
* str - string to hash
|
|
* hval - previous hash value or 0 if first call
|
|
*
|
|
* returns:
|
|
* 32 bit hash as a static hash type
|
|
*
|
|
* NOTE: To use the 32 bit FNV-0 historic hash, use FNV0_32_INIT as the hval
|
|
* argument on the first call to either fnv_32_buf() or fnv_32_str().
|
|
*
|
|
* NOTE: To use the recommended 32 bit FNV-1 hash, use FNV1_32_INIT as the hval
|
|
* argument on the first call to either fnv_32_buf() or fnv_32_str().
|
|
*/
|
|
Fnv32_t
|
|
fnv_32_str(char *str, Fnv32_t hval)
|
|
{
|
|
unsigned char *s = (unsigned char *)str; /* unsigned string */
|
|
|
|
/*
|
|
* FNV-1 hash each octet in the buffer
|
|
*/
|
|
while (*s) {
|
|
|
|
/* multiply by the 32 bit FNV magic prime mod 2^32 */
|
|
#if defined(NO_FNV_GCC_OPTIMIZATION)
|
|
hval *= FNV_32_PRIME;
|
|
#else
|
|
hval += (hval<<1) + (hval<<4) + (hval<<7) + (hval<<8) + (hval<<24);
|
|
#endif
|
|
|
|
/* xor the bottom with the current octet */
|
|
hval ^= (Fnv32_t)*s++;
|
|
}
|
|
|
|
/* return our new hash value */
|
|
return hval;
|
|
}
|