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.
This patch integrates that code into the rte_jhash library.
Signed-off-by: Pablo de Lara <pablo.de.lara.guarch at intel.com>
---
lib/librte_hash/rte_jhash.h | 266 +++++++++++++++++++++++++++++++------------
1 files changed, 193 insertions(+), 73 deletions(-)
diff --git a/lib/librte_hash/rte_jhash.h b/lib/librte_hash/rte_jhash.h
index a4bf5a1..41297ab 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 +45,62 @@ extern "C" {
#endif
#include <stdint.h>
+#include <string.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
+
+#if RTE_BYTE_ORDER == RTE_LITTLE_ENDIAN
+#define BIT_SHIFT(x, y, k) (((x) >> (k)) | ((uint64_t)(y) << (32-(k))))
+#else
+#define BIT_SHIFT(x, y, k) (((uint64_t)(x) << (k)) | ((y) >> (32-(k))))
+#endif
+
+#define LOWER8b_MASK rte_le_to_cpu_32(0xff)
+#define LOWER16b_MASK rte_le_to_cpu_32(0xffff)
+#define LOWER24b_MASK rte_le_to_cpu_32(0xffffff)
/**
* The most generic version, hashes an arbitrary sequence
@@ -95,42 +119,130 @@ 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;
- 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];
+ /* Check key alignment. For x86 architecture, first case is always
optimal */
+#if defined(RTE_ARCH_X86_64) || defined(RTE_ARCH_I686) ||
defined(RTE_ARCH_X86_X32)
+ const uint32_t *k = key;
+ const uint32_t s = 0;
+#else
+ const uint32_t *k = (uint32_t *)(uintptr_t)key & (uintptr_t)~3);
+ const uint32_t s = ((uintptr_t)key & 3) * CHAR_BIT;
+#endif
- __rte_jhash_mix(a,b,c);
+ if (s == 0) {
+ while (length > 12) {
+ a += k[0];
+ b += k[1];
+ c += k[2];
- k += (3 * sizeof(uint32_t)), k32 += 3;
- len -= (3 * sizeof(uint32_t));
- }
+ __rte_jhash_mix(a, b, c);
- 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;
- };
+ k += 3;
+ length -= 12;
+ }
- __rte_jhash_mix(a,b,c);
+ switch (length) {
+ case 12:
+ c += k[2]; b += k[1]; a += k[0]; break;
+ case 11:
+ c += k[2] & LOWER24b_MASK; b += k[1]; a += k[0]; break;
+ case 10:
+ c += k[2] & LOWER16b_MASK; b += k[1]; a += k[0]; break;
+ case 9:
+ c += k[2] & LOWER8b_MASK; b += k[1]; a += k[0]; break;
+ case 8:
+ b += k[1]; a += k[0]; break;
+ case 7:
+ b += k[1] & LOWER24b_MASK; a += k[0]; break;
+ case 6:
+ b += k[1] & LOWER16b_MASK; a += k[0]; break;
+ case 5:
+ b += k[1] & LOWER8b_MASK; a += k[0]; break;
+ case 4:
+ a += k[0]; break;
+ case 3:
+ a += k[0] & LOWER24b_MASK; break;
+ case 2:
+ a += k[0] & LOWER16b_MASK; break;
+ case 1:
+ a += k[0] & LOWER8b_MASK; break;
+ /* zero length strings require no mixing */
+ case 0:
+ return c;
+ };
+ } else {
+ /* all but the last block: affect some 32 bits of (a, b, c) */
+ while (length > 12) {
+ a += BIT_SHIFT(k[0], k[1], s);
+ b += BIT_SHIFT(k[1], k[2], s);
+ c += BIT_SHIFT(k[2], k[3], s);
+ __rte_jhash_mix(a, b, c);
+
+ k += 3;
+ length -= 12;
+ }
+
+ /* last block: affect all 32 bits of (c) */
+ switch (length) {
+ case 12:
+ a += BIT_SHIFT(k[0], k[1], s);
+ b += BIT_SHIFT(k[1], k[2], s);
+ c += BIT_SHIFT(k[2], k[3], s);
+ break;
+ case 11:
+ a += BIT_SHIFT(k[0], k[1], s);
+ b += BIT_SHIFT(k[1], k[2], s);
+ c += BIT_SHIFT(k[2], k[3], s) & LOWER24b_MASK;
+ break;
+ case 10:
+ a += BIT_SHIFT(k[0], k[1], s);
+ b += BIT_SHIFT(k[1], k[2], s);
+ c += BIT_SHIFT(k[2], k[3], s) & LOWER16b_MASK;
+ break;
+ case 9:
+ a += BIT_SHIFT(k[0], k[1], s);
+ b += BIT_SHIFT(k[1], k[2], s);
+ c += BIT_SHIFT(k[2], k[3], s) & LOWER8b_MASK;
+ break;
+ case 8:
+ a += BIT_SHIFT(k[0], k[1], s);
+ b += BIT_SHIFT(k[1], k[2], s);
+ break;
+ case 7:
+ a += BIT_SHIFT(k[0], k[1], s);
+ b += BIT_SHIFT(k[1], k[2], s) & LOWER24b_MASK;
+ break;
+ case 6:
+ a += BIT_SHIFT(k[0], k[1], s);
+ b += BIT_SHIFT(k[1], k[2], s) & LOWER16b_MASK;
+ break;
+ case 5:
+ a += BIT_SHIFT(k[0], k[1], s);
+ b += BIT_SHIFT(k[1], k[2], s) & LOWER8b_MASK;
+ break;
+ case 4:
+ a += BIT_SHIFT(k[0], k[1], s);
+ break;
+ case 3:
+ a += BIT_SHIFT(k[0], k[1], s) & LOWER24b_MASK;
+ break;
+ case 2:
+ a += BIT_SHIFT(k[0], k[1], s) & LOWER16b_MASK;
+ break;
+ case 1:
+ a += BIT_SHIFT(k[0], k[1], s) & LOWER8b_MASK;
+ break;
+ /* zero length strings require no mixing */
+ case 0:
+ return c;
+ }
+ }
+
+ __rte_jhash_final(a, b, c);
return c;
}
@@ -151,33 +263,51 @@ 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;
}
+static inline uint32_t
+__rte_jhash_3words(uint32_t a, uint32_t b, uint32_t c, uint32_t initval)
+{
+ a += RTE_JHASH_GOLDEN_RATIO + initval;
+ b += RTE_JHASH_GOLDEN_RATIO + initval;
+ c += RTE_JHASH_GOLDEN_RATIO + initval;
+
+ __rte_jhash_final(a, b, c);
+
+ return c;
+}
/**
* A special ultra-optimized versions that knows it is hashing exactly
@@ -197,17 +327,7 @@ rte_jhash2(const uint32_t *k, uint32_t length, uint32_t
initval)
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;
+ return __rte_jhash_3words(a + 12, b + 12, c + 12, initval);
}
/**
@@ -226,7 +346,7 @@ rte_jhash_3words(uint32_t a, uint32_t b, uint32_t c,
uint32_t initval)
static inline uint32_t
rte_jhash_2words(uint32_t a, uint32_t b, uint32_t initval)
{
- return rte_jhash_3words(a, b, 0, initval);
+ return __rte_jhash_3words(a + 8, b + 8, 8, initval);
}
/**
@@ -243,7 +363,7 @@ rte_jhash_2words(uint32_t a, uint32_t b, uint32_t initval)
static inline uint32_t
rte_jhash_1word(uint32_t a, uint32_t initval)
{
- return rte_jhash_3words(a, 0, 0, initval);
+ return __rte_jhash_3words(a + 4, 4, 4, initval);
}
#ifdef __cplusplus
--
1.7.4.1
