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/*-
* BSD LICENSE
*
* Copyright(c) 2010-2014 Intel Corporation. All rights reserved.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Intel Corporation nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef _RTE_JHASH_H
#define _RTE_JHASH_H
/**
* @file
*
* jhash functions.
*/
#ifdef __cplusplus
extern "C" {
#endif
#include <stdint.h>
/* jhash.h: Jenkins hash support.
*
* Copyright (C) 1996 Bob Jenkins (bob_jenkins@burtleburtle.net)
*
* http://burtleburtle.net/bob/hash/
*
* These are the credits from Bob's sources:
*
* lookup2.c, by Bob Jenkins, December 1996, Public Domain.
* hash(), hash2(), hash3, and mix() are externally useful functions.
* Routines to test the hash are included if SELF_TEST is defined.
* You can use this free for any purpose. It has no warranty.
*
* $FreeBSD$
*/
/** @internal Internal function. NOTE: Arguments are modified. */
#define __rte_jhash_mix(a, b, c) do { \
a -= b; a -= c; a ^= (c>>13); \
b -= c; b -= a; b ^= (a<<8); \
c -= a; c -= b; c ^= (b>>13); \
a -= b; a -= c; a ^= (c>>12); \
b -= c; b -= a; b ^= (a<<16); \
c -= a; c -= b; c ^= (b>>5); \
a -= b; a -= c; a ^= (c>>3); \
b -= c; b -= a; b ^= (a<<10); \
c -= a; c -= b; c ^= (b>>15); \
} while (0)
/** The golden ratio: an arbitrary value. */
#define RTE_JHASH_GOLDEN_RATIO 0x9e3779b9
/**
* The most generic version, hashes an arbitrary sequence
* of bytes. No alignment or length assumptions are made about
* the input key.
*
* @param key
* Key to calculate hash of.
* @param length
* Length of key in bytes.
* @param initval
* Initialising value of hash.
* @return
* Calculated hash value.
*/
static inline uint32_t
rte_jhash(const void *key, uint32_t length, uint32_t initval)
{
uint32_t a, b, c, len;
const uint8_t *k = (const uint8_t *)key;
const uint32_t *k32 = (const uint32_t *)key;
len = length;
a = b = RTE_JHASH_GOLDEN_RATIO;
c = initval;
while (len >= 12) {
a += k32[0];
b += k32[1];
c += k32[2];
__rte_jhash_mix(a,b,c);
k += (3 * sizeof(uint32_t)), k32 += 3;
len -= (3 * sizeof(uint32_t));
}
c += length;
switch (len) {
case 11: c += ((uint32_t)k[10] << 24);
case 10: c += ((uint32_t)k[9] << 16);
case 9 : c += ((uint32_t)k[8] << 8);
case 8 : b += ((uint32_t)k[7] << 24);
case 7 : b += ((uint32_t)k[6] << 16);
case 6 : b += ((uint32_t)k[5] << 8);
case 5 : b += k[4];
case 4 : a += ((uint32_t)k[3] << 24);
case 3 : a += ((uint32_t)k[2] << 16);
case 2 : a += ((uint32_t)k[1] << 8);
case 1 : a += k[0];
default: break;
};
__rte_jhash_mix(a,b,c);
return c;
}
/**
* A special optimized version that handles 1 or more of uint32_ts.
* The length parameter here is the number of uint32_ts in the key.
*
* @param k
* Key to calculate hash of.
* @param length
* Length of key in units of 4 bytes.
* @param initval
* Initialising value of hash.
* @return
* Calculated hash value.
*/
static inline uint32_t
rte_jhash2(const uint32_t *k, uint32_t length, uint32_t initval)
{
uint32_t a, b, c, len;
a = b = RTE_JHASH_GOLDEN_RATIO;
c = initval;
len = length;
while (len >= 3) {
a += k[0];
b += k[1];
c += k[2];
__rte_jhash_mix(a, b, c);
k += 3; len -= 3;
}
c += length * 4;
switch (len) {
case 2 : b += k[1];
case 1 : a += k[0];
default: break;
};
__rte_jhash_mix(a,b,c);
return c;
}
/**
* A special ultra-optimized versions that knows it is hashing exactly
* 3 words.
*
* @param a
* First word to calcuate hash of.
* @param b
* Second word to calcuate hash of.
* @param c
* Third word to calcuate hash of.
* @param initval
* Initialising value of hash.
* @return
* Calculated hash value.
*/
static inline uint32_t
rte_jhash_3words(uint32_t a, uint32_t b, uint32_t c, uint32_t initval)
{
a += RTE_JHASH_GOLDEN_RATIO;
b += RTE_JHASH_GOLDEN_RATIO;
c += initval;
__rte_jhash_mix(a, b, c);
/*
* NOTE: In particular the "c += length; __rte_jhash_mix(a,b,c);"
* normally done at the end is not done here.
*/
return c;
}
/**
* A special ultra-optimized versions that knows it is hashing exactly
* 2 words.
*
* @param a
* First word to calcuate hash of.
* @param b
* Second word to calcuate hash of.
* @param initval
* Initialising value of hash.
* @return
* Calculated hash value.
*/
static inline uint32_t
rte_jhash_2words(uint32_t a, uint32_t b, uint32_t initval)
{
return rte_jhash_3words(a, b, 0, initval);
}
/**
* A special ultra-optimized versions that knows it is hashing exactly
* 1 word.
*
* @param a
* Word to calcuate hash of.
* @param initval
* Initialising value of hash.
* @return
* Calculated hash value.
*/
static inline uint32_t
rte_jhash_1word(uint32_t a, uint32_t initval)
{
return rte_jhash_3words(a, 0, 0, initval);
}
#ifdef __cplusplus
}
#endif
#endif /* _RTE_JHASH_H */
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