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49 #include <rte_byteorder.h>
51 /* jhash.h: Jenkins hash support.
53 * Copyright (C) 2006 Bob Jenkins (bob_jenkins@burtleburtle.net)
55 * http://burtleburtle.net/bob/hash/
57 * These are the credits from Bob's sources:
59 * lookup3.c, by Bob Jenkins, May 2006, Public Domain.
61 * These are functions for producing 32-bit hashes for hash table lookup.
62 * hashword(), hashlittle(), hashlittle2(), hashbig(), mix(), and final()
63 * are externally useful functions. Routines to test the hash are included
64 * if SELF_TEST is defined. You can use this free for any purpose. It's in
65 * the public domain. It has no warranty.
70 #define rot(x, k) (((x) << (k)) | ((x) >> (32-(k))))
72 /** @internal Internal function. NOTE: Arguments are modified. */
73 #define __rte_jhash_mix(a, b, c) do { \
74 a -= c; a ^= rot(c, 4); c += b; \
75 b -= a; b ^= rot(a, 6); a += c; \
76 c -= b; c ^= rot(b, 8); b += a; \
77 a -= c; a ^= rot(c, 16); c += b; \
78 b -= a; b ^= rot(a, 19); a += c; \
79 c -= b; c ^= rot(b, 4); b += a; \
82 #define __rte_jhash_final(a, b, c) do { \
83 c ^= b; c -= rot(b, 14); \
84 a ^= c; a -= rot(c, 11); \
85 b ^= a; b -= rot(a, 25); \
86 c ^= b; c -= rot(b, 16); \
87 a ^= c; a -= rot(c, 4); \
88 b ^= a; b -= rot(a, 14); \
89 c ^= b; c -= rot(b, 24); \
92 /** The golden ratio: an arbitrary value. */
93 #define RTE_JHASH_GOLDEN_RATIO 0xdeadbeef
95 #if RTE_BYTE_ORDER == RTE_LITTLE_ENDIAN
96 #define BIT_SHIFT(x, y, k) (((x) >> (k)) | ((uint64_t)(y) << (32-(k))))
98 #define BIT_SHIFT(x, y, k) (((uint64_t)(x) << (k)) | ((y) >> (32-(k))))
101 #define LOWER8b_MASK rte_le_to_cpu_32(0xff)
102 #define LOWER16b_MASK rte_le_to_cpu_32(0xffff)
103 #define LOWER24b_MASK rte_le_to_cpu_32(0xffffff)
106 * The most generic version, hashes an arbitrary sequence
107 * of bytes. No alignment or length assumptions are made about
111 * Key to calculate hash of.
113 * Length of key in bytes.
115 * Initialising value of hash.
117 * Calculated hash value.
119 static inline uint32_t
120 rte_jhash(const void *key, uint32_t length, uint32_t initval)
124 /* Set up the internal state */
125 a = b = c = RTE_JHASH_GOLDEN_RATIO + ((uint32_t)length) + initval;
127 /* Check key alignment. For x86 architecture, first case is always optimal */
128 #if defined(RTE_ARCH_X86_64) || defined(RTE_ARCH_I686) || defined(RTE_ARCH_X86_X32)
129 const uint32_t *k = key;
130 const uint32_t s = 0;
132 const uint32_t *k = (uint32_t *)(uintptr_t)key & (uintptr_t)~3);
133 const uint32_t s = ((uintptr_t)key & 3) * CHAR_BIT;
137 while (length > 12) {
142 __rte_jhash_mix(a, b, c);
150 c += k[2]; b += k[1]; a += k[0]; break;
152 c += k[2] & LOWER24b_MASK; b += k[1]; a += k[0]; break;
154 c += k[2] & LOWER16b_MASK; b += k[1]; a += k[0]; break;
156 c += k[2] & LOWER8b_MASK; b += k[1]; a += k[0]; break;
158 b += k[1]; a += k[0]; break;
160 b += k[1] & LOWER24b_MASK; a += k[0]; break;
162 b += k[1] & LOWER16b_MASK; a += k[0]; break;
164 b += k[1] & LOWER8b_MASK; a += k[0]; break;
168 a += k[0] & LOWER24b_MASK; break;
170 a += k[0] & LOWER16b_MASK; break;
172 a += k[0] & LOWER8b_MASK; break;
173 /* zero length strings require no mixing */
178 /* all but the last block: affect some 32 bits of (a, b, c) */
179 while (length > 12) {
180 a += BIT_SHIFT(k[0], k[1], s);
181 b += BIT_SHIFT(k[1], k[2], s);
182 c += BIT_SHIFT(k[2], k[3], s);
183 __rte_jhash_mix(a, b, c);
189 /* last block: affect all 32 bits of (c) */
192 a += BIT_SHIFT(k[0], k[1], s);
193 b += BIT_SHIFT(k[1], k[2], s);
194 c += BIT_SHIFT(k[2], k[3], s);
197 a += BIT_SHIFT(k[0], k[1], s);
198 b += BIT_SHIFT(k[1], k[2], s);
199 c += BIT_SHIFT(k[2], k[3], s) & LOWER24b_MASK;
202 a += BIT_SHIFT(k[0], k[1], s);
203 b += BIT_SHIFT(k[1], k[2], s);
204 c += BIT_SHIFT(k[2], k[3], s) & LOWER16b_MASK;
207 a += BIT_SHIFT(k[0], k[1], s);
208 b += BIT_SHIFT(k[1], k[2], s);
209 c += BIT_SHIFT(k[2], k[3], s) & LOWER8b_MASK;
212 a += BIT_SHIFT(k[0], k[1], s);
213 b += BIT_SHIFT(k[1], k[2], s);
216 a += BIT_SHIFT(k[0], k[1], s);
217 b += BIT_SHIFT(k[1], k[2], s) & LOWER24b_MASK;
220 a += BIT_SHIFT(k[0], k[1], s);
221 b += BIT_SHIFT(k[1], k[2], s) & LOWER16b_MASK;
224 a += BIT_SHIFT(k[0], k[1], s);
225 b += BIT_SHIFT(k[1], k[2], s) & LOWER8b_MASK;
228 a += BIT_SHIFT(k[0], k[1], s);
231 a += BIT_SHIFT(k[0], k[1], s) & LOWER24b_MASK;
234 a += BIT_SHIFT(k[0], k[1], s) & LOWER16b_MASK;
237 a += BIT_SHIFT(k[0], k[1], s) & LOWER8b_MASK;
239 /* zero length strings require no mixing */
245 __rte_jhash_final(a, b, c);
251 * A special optimized version that handles 1 or more of uint32_ts.
252 * The length parameter here is the number of uint32_ts in the key.
255 * Key to calculate hash of.
257 * Length of key in units of 4 bytes.
259 * Initialising value of hash.
261 * Calculated hash value.
263 static inline uint32_t
264 rte_jhash2(const uint32_t *k, uint32_t length, uint32_t initval)
268 /* Set up the internal state */
269 a = b = c = RTE_JHASH_GOLDEN_RATIO + (((uint32_t)length) << 2) + initval;
271 /* Handle most of the key */
277 __rte_jhash_mix(a, b, c);
283 /* Handle the last 3 uint32_t's */
293 __rte_jhash_final(a, b, c);
295 /* case 0: nothing left to add */
303 static inline uint32_t
304 __rte_jhash_3words(uint32_t a, uint32_t b, uint32_t c, uint32_t initval)
306 a += RTE_JHASH_GOLDEN_RATIO + initval;
307 b += RTE_JHASH_GOLDEN_RATIO + initval;
308 c += RTE_JHASH_GOLDEN_RATIO + initval;
310 __rte_jhash_final(a, b, c);
316 * A special ultra-optimized versions that knows it is hashing exactly
320 * First word to calcuate hash of.
322 * Second word to calcuate hash of.
324 * Third word to calcuate hash of.
326 * Initialising value of hash.
328 * Calculated hash value.
330 static inline uint32_t
331 rte_jhash_3words(uint32_t a, uint32_t b, uint32_t c, uint32_t initval)
333 return __rte_jhash_3words(a + 12, b + 12, c + 12, initval);
337 * A special ultra-optimized versions that knows it is hashing exactly
341 * First word to calcuate hash of.
343 * Second word to calcuate hash of.
345 * Initialising value of hash.
347 * Calculated hash value.
349 static inline uint32_t
350 rte_jhash_2words(uint32_t a, uint32_t b, uint32_t initval)
352 return __rte_jhash_3words(a + 8, b + 8, 8, initval);
356 * A special ultra-optimized versions that knows it is hashing exactly
360 * Word to calcuate hash of.
362 * Initialising value of hash.
364 * Calculated hash value.
366 static inline uint32_t
367 rte_jhash_1word(uint32_t a, uint32_t initval)
369 return __rte_jhash_3words(a + 4, 4, 4, initval);
376 #endif /* _RTE_JHASH_H */