Jenkins hash function was developed originally in 1996, and was integrated in first versions of DPDK. The function has been improved in 2006, achieving up to 60% better performance, compared to the original one.
Check out: http://burtleburtle.net/bob/c/lookup3.c This patch integrates that code in the rte_jhash library, adding also a new function rte_jhash_word2, that returns two different hash values, for a single key. Signed-off-by: Pablo de Lara <pablo.de.lara.guarch at intel.com> --- lib/librte_hash/rte_jhash.h | 407 ++++++++++++++++++++++++++++++++++++------- 1 files changed, 347 insertions(+), 60 deletions(-) diff --git a/lib/librte_hash/rte_jhash.h b/lib/librte_hash/rte_jhash.h index a4bf5a1..3de006d 100644 --- a/lib/librte_hash/rte_jhash.h +++ b/lib/librte_hash/rte_jhash.h @@ -1,7 +1,7 @@ /*- * BSD LICENSE * - * Copyright(c) 2010-2014 Intel Corporation. All rights reserved. + * Copyright(c) 2010-2015 Intel Corporation. All rights reserved. * All rights reserved. * * Redistribution and use in source and binary forms, with or without @@ -45,38 +45,51 @@ extern "C" { #endif #include <stdint.h> +#include <rte_byteorder.h> /* jhash.h: Jenkins hash support. * - * Copyright (C) 1996 Bob Jenkins (bob_jenkins at burtleburtle.net) + * Copyright (C) 2006 Bob Jenkins (bob_jenkins at 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. + * lookup3.c, by Bob Jenkins, May 2006, Public Domain. + * + * These are functions for producing 32-bit hashes for hash table lookup. + * hashword(), hashlittle(), hashlittle2(), hashbig(), mix(), and final() + * 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's in + * the public domain. It has no warranty. * * $FreeBSD$ */ +#define rot(x, k) (((x)<<(k)) | ((x)>>(32-(k)))) + /** @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); \ + a -= c; a ^= rot(c, 4); c += b; \ + b -= a; b ^= rot(a, 6); a += c; \ + c -= b; c ^= rot(b, 8); b += a; \ + a -= c; a ^= rot(c, 16); c += b; \ + b -= a; b ^= rot(a, 19); a += c; \ + c -= b; c ^= rot(b, 4); b += a; \ +} while (0) + +#define __rte_jhash_final(a, b, c) do { \ + c ^= b; c -= rot(b, 14); \ + a ^= c; a -= rot(c, 11); \ + b ^= a; b -= rot(a, 25); \ + c ^= b; c -= rot(b, 16); \ + a ^= c; a -= rot(c, 4); \ + b ^= a; b -= rot(a, 14); \ + c ^= b; c -= rot(b, 24); \ } while (0) /** The golden ratio: an arbitrary value. */ -#define RTE_JHASH_GOLDEN_RATIO 0x9e3779b9 +#define RTE_JHASH_GOLDEN_RATIO 0xdeadbeef /** * The most generic version, hashes an arbitrary sequence @@ -95,42 +108,256 @@ extern "C" { 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; + uint32_t a, b, c; + union { + const void *ptr; + size_t i; + } u; - len = length; - a = b = RTE_JHASH_GOLDEN_RATIO; - c = initval; + /* Set up the internal state */ + a = b = c = RTE_JHASH_GOLDEN_RATIO + ((uint32_t)length) + initval; - while (len >= 12) { - a += k32[0]; - b += k32[1]; - c += k32[2]; + u.ptr = key; - __rte_jhash_mix(a,b,c); + if ((u.i & 0x3) == 0) { + const uint32_t *k = (const uint32_t *)key; - k += (3 * sizeof(uint32_t)), k32 += 3; - len -= (3 * sizeof(uint32_t)); - } + while (length > 12) { + a += k[0]; + b += k[1]; + c += k[2]; - 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); + + k += 3; + length -= 12; + } + + switch (length) { +#if RTE_BYTE_ORDER == RTE_LITTLE_ENDIAN + case 12: + c += k[2]; b += k[1]; a += k[0]; break; + case 11: + c += k[2]&0xffffff; b += k[1]; a += k[0]; break; + case 10: + c += k[2]&0xffff; b += k[1]; a += k[0]; break; + case 9: + c += k[2]&0xff; b += k[1]; a += k[0]; break; + case 8: + b += k[1]; a += k[0]; break; + case 7: + b += k[1]&0xffffff; a += k[0]; break; + case 6: + b += k[1]&0xffff; a += k[0]; break; + case 5: + b += k[1]&0xff; a += k[0]; break; + case 4: + a += k[0]; break; + case 3: + a += k[0]&0xffffff; break; + case 2: + a += k[0]&0xffff; break; + case 1: + a += k[0]&0xff; break; +#else + case 12: + c += k[2]; b += k[1]; a += k[0]; break; + case 11: + c += k[2]&0xffffff00; b += k[1]; a += k[0]; break; + case 10: + c += k[2]&0xffff0000; b += k[1]; a += k[0]; break; + case 9: + c += k[2]&0xff000000; b += k[1]; a += k[0]; break; + case 8: + b += k[1]; a += k[0]; break; + case 7: + b += k[1]&0xffffff00; a += k[0]; break; + case 6: + b += k[1]&0xffff0000; a += k[0]; break; + case 5: + b += k[1]&0xff000000; a += k[0]; break; + case 4: + a += k[0]; break; + case 3: + a += k[0]&0xffffff00; break; + case 2: + a += k[0]&0xffff0000; break; + case 1: + a += k[0]&0xff000000; break; +#endif + /* zero length strings require no mixing */ + case 0: + return c; + }; +#if RTE_BYTE_ORDER == RTE_LITTLE_ENDIAN + } else if ((u.i & 0x1) == 0) { + /* read 16-bit chunks */ + const uint16_t *k = (const uint16_t *)key; + const uint8_t *k8; + + /* all but last block: aligned reads and different mixing */ + while (length > 12) { + a += k[0] + (((uint32_t)k[1])<<16); + b += k[2] + (((uint32_t)k[3])<<16); + c += k[4] + (((uint32_t)k[5])<<16); + + __rte_jhash_mix(a, b, c); + + k += 6; + length -= 12; + } + + /* handle the last (probably partial) block */ + k8 = (const uint8_t *)k; + switch (length) { + case 12: + c += k[4]+(((uint32_t)k[5])<<16); + b += k[2]+(((uint32_t)k[3])<<16); + a += k[0]+(((uint32_t)k[1])<<16); + break; + case 11: + /* fall through */ + c += ((uint32_t)k8[10])<<16; + case 10: + c += k[4]; + b += k[2]+(((uint32_t)k[3])<<16); + a += k[0]+(((uint32_t)k[1])<<16); + break; + case 9: + /* fall through */ + c += k8[8]; + case 8: + b += k[2]+(((uint32_t)k[3])<<16); + a += k[0]+(((uint32_t)k[1])<<16); + break; + case 7: + /* fall through */ + b += ((uint32_t)k8[6])<<16; + case 6: + b += k[2]; + a += k[0]+(((uint32_t)k[1])<<16); + break; + case 5: + /* fall through */ + b += k8[4]; + case 4: + a += k[0]+(((uint32_t)k[1])<<16); + break; + case 3: + /* fall through */ + a += ((uint32_t)k8[2])<<16; + case 2: + a += k[0]; + break; + case 1: + a += k8[0]; + break; + case 0: + /* zero length requires no mixing */ + return c; + } +#endif + } else { + const uint8_t *k = (const uint8_t *)key; + + /* all but the last block: affect some 32 bits of (a, b, c) */ + while (length > 12) { +#if RTE_BYTE_ORDER == RTE_LITTLE_ENDIAN + a += k[0]; + a += ((uint32_t)k[1])<<8; + a += ((uint32_t)k[2])<<16; + a += ((uint32_t)k[3])<<24; + b += k[4]; + b += ((uint32_t)k[5])<<8; + b += ((uint32_t)k[6])<<16; + b += ((uint32_t)k[7])<<24; + c += k[8]; + c += ((uint32_t)k[9])<<8; + c += ((uint32_t)k[10])<<16; + c += ((uint32_t)k[11])<<24; +#else + a += ((uint32_t)k[0])<<24; + a += ((uint32_t)k[1])<<16; + a += ((uint32_t)k[2])<<8; + a += ((uint32_t)k[3]); + b += ((uint32_t)k[4])<<24; + b += ((uint32_t)k[5])<<16; + b += ((uint32_t)k[6])<<8; + b += ((uint32_t)k[7]); + c += ((uint32_t)k[8])<<32; + c += ((uint32_t)k[9])<<16; + c += ((uint32_t)k[10])<<8; + c += ((uint32_t)k[11]); +#endif + + __rte_jhash_mix(a, b, c); - __rte_jhash_mix(a,b,c); + k += 12; + length -= 12; + } + + /* last block: affect all 32 bits of (c) */ + /* all the case statements fall through */ + switch (length) { +#if RTE_BYTE_ORDER == RTE_LITTLE_ENDIAN + case 12: + c += ((uint32_t)k[11])<<24; + case 11: + c += ((uint32_t)k[10])<<16; + case 10: + c += ((uint32_t)k[9])<<8; + case 9: + c += k[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]; + break; +#else + case 12: + c += k[11]; + case 11: + c += ((uint32_t)k[10])<<8; + case 10: + c += ((uint32_t)k[9])<<16; + case 9: + c += ((uint32_t)k[8])<<24; + case 8: + b += k[7]; + case 7: + b += ((uint32_t)k[6])<<8; + case 6: + b += ((uint32_t)k[5])<<16; + case 5: + b += ((uint32_t)k[4])<<24; + case 4: + a += k[3]; + case 3: + a += ((uint32_t)k[2])<<8; + case 2: + a += ((uint32_t)k[1])<<16; + case 1: + a += ((uint32_t)k[0])<<24; + break; +#endif + case 0: + return c; + } + } + + __rte_jhash_final(a, b, c); return c; } @@ -151,33 +378,93 @@ rte_jhash(const void *key, uint32_t length, uint32_t initval) static inline uint32_t rte_jhash2(const uint32_t *k, uint32_t length, uint32_t initval) { - uint32_t a, b, c, len; + uint32_t a, b, c; - a = b = RTE_JHASH_GOLDEN_RATIO; - c = initval; - len = length; + /* Set up the internal state */ + a = b = c = RTE_JHASH_GOLDEN_RATIO + (((uint32_t)length)<<2) + initval; - while (len >= 3) { + /* Handle most of the key */ + while (length > 3) { a += k[0]; b += k[1]; c += k[2]; + __rte_jhash_mix(a, b, c); - k += 3; len -= 3; - } - c += length * 4; + k += 3; + length -= 3; + } - switch (len) { - case 2 : b += k[1]; - case 1 : a += k[0]; - default: break; + /* Handle the last 3 uint32_t's */ + switch (length) { + case 3: + c += k[2]; + case 2: + b += k[1]; + case 1: + a += k[0]; + __rte_jhash_final(a, b, c); + /* case 0: nothing left to add */ + case 0: + break; }; - __rte_jhash_mix(a,b,c); - return c; } +/** + * Same as rte_jhash2, but take two seeds and return two uint32_ts. + * pc and pb must be non-null, and *pc and *pb must both be initialized + * with seeds. If you pass in (*pb)=0, the output (*pc) will be + * the same as the return value from rte_jhash. + * + * @param k + * Key to calculate hash of. + * @param length + * Length of key in units of 4 bytes. + * @param pc + * IN: seed OUT: primary hash value. + * @param pc + * IN: second seed OUT: secondary hash value. + */ +static inline void +rte_jhash_word2(const uint32_t *k, uint32_t length, uint32_t *pc, uint32_t *pb) +{ + uint32_t a, b, c; + + /* Set up the internal state */ + a = b = c = RTE_JHASH_GOLDEN_RATIO + (((uint32_t)length)<<2) + *pc; + c += *pb; + + /* Handle most of the key */ + while (length > 3) { + a += k[0]; + b += k[1]; + c += k[2]; + + __rte_jhash_mix(a, b, c); + + k += 3; + length -= 3; + } + + /* Handle the last 3 uint32_t's */ + switch (length) { + case 3: + c += k[2]; + case 2: + b += k[1]; + case 1: + a += k[0]; + __rte_jhash_final(a, b, c); + /* case 0: nothing left to add */ + case 0: + break; + }; + + *pc = c; + *pb = b; +} /** * A special ultra-optimized versions that knows it is hashing exactly -- 1.7.4.1
