libosmocore 1.13.1.1-afb4 Osmocom core library

jhash.h
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1#pragma once
2#include <osmocom/core/bit32gen.h>
3
4/* Below is a partial copy of
5 * https://raw.githubusercontent.com/torvalds/linux/3eb3c33c1d87029a3832e205eebd59cfb56ba3a4/tools/include/linux/bitops.h
6 * with an osmo_ prefix applied to avoid any collisions.
7 */
8/* SPDX-License-Identifier: GPL-2.0 */
14 static inline uint32_t osmo_rol32(uint32_t word, unsigned int shift)
15{
16 return (word << shift) | (word >> ((-shift) & 31));
17}
18
19/* Below is a partial copy of
20 * https://raw.githubusercontent.com/torvalds/linux/22c033989c3eb9731ad0c497dfab4231b8e367d6/include/linux/unaligned/packed_struct.h
21 * with an osmo_ prefix applied to avoid any collisions.
22 */
23 struct osmo_unaligned_cpu32 {
24 uint32_t x;
25} __attribute__((__packed__));
26
27 static inline uint32_t osmo_get_unaligned_cpu32(const void *p)
28{
29 const struct osmo_unaligned_cpu32 *ptr = (const struct osmo_unaligned_cpu32 *)p;
30 return ptr->x;
31}
32
33/* Below is a partial copy of
34 * https://raw.githubusercontent.com/torvalds/linux/79e3ea5aab48c83de9410e43b52895406847eca7/tools/include/linux/jhash.h
35 * with an osmo_ prefix applied to avoid any collisions.
36 */
37/* jhash.h: Jenkins hash support.
38 *
39 * Copyright (C) 2006. Bob Jenkins (bob_jenkins@burtleburtle.net)
40 *
41 * https://burtleburtle.net/bob/hash/
42 *
43 * These are the credits from Bob's sources:
44 *
45 * lookup3.c, by Bob Jenkins, May 2006, Public Domain.
46 *
47 * These are functions for producing 32-bit hashes for hash table lookup.
48 * hashword(), hashlittle(), hashlittle2(), hashbig(), mix(), and final()
49 * are externally useful functions. Routines to test the hash are included
50 * if SELF_TEST is defined. You can use this free for any purpose. It's in
51 * the public domain. It has no warranty.
52 *
53 * Copyright (C) 2009-2010 Jozsef Kadlecsik (kadlec@blackhole.kfki.hu)
54 *
55 * I've modified Bob's hash to be useful in the Linux kernel, and
56 * any bugs present are my fault.
57 * Jozsef
58 */
59
60/* OSMO_JHASH_MIX -- mix 3 32-bit values reversibly. */
61#define OSMO_JHASH_MIX(a, b, c) \
62{ \
63 a -= c; a ^= osmo_rol32(c, 4); c += b; \
64 b -= a; b ^= osmo_rol32(a, 6); a += c; \
65 c -= b; c ^= osmo_rol32(b, 8); b += a; \
66 a -= c; a ^= osmo_rol32(c, 16); c += b; \
67 b -= a; b ^= osmo_rol32(a, 19); a += c; \
68 c -= b; c ^= osmo_rol32(b, 4); b += a; \
69}
70
71/* OSMO_JHASH_FINAL - final mixing of 3 32-bit values (a,b,c) into c */
72#define OSMO_JHASH_FINAL(a, b, c) \
73{ \
74 c ^= b; c -= osmo_rol32(b, 14); \
75 a ^= c; a -= osmo_rol32(c, 11); \
76 b ^= a; b -= osmo_rol32(a, 25); \
77 c ^= b; c -= osmo_rol32(b, 16); \
78 a ^= c; a -= osmo_rol32(c, 4); \
79 b ^= a; b -= osmo_rol32(a, 14); \
80 c ^= b; c -= osmo_rol32(b, 24); \
81}
82
83/* An arbitrary initial parameter */
84#define JHASH_INITVAL 0xdeadbeef
85
86/* osmo_jhash - hash an arbitrary key
87 * @k: sequence of bytes as key
88 * @length: the length of the key
89 * @initval: the previous hash, or an arbitray value
90 *
91 * The generic version, hashes an arbitrary sequence of bytes.
92 * No alignment or length assumptions are made about the input key.
93 *
94 * Returns the hash value of the key. The result depends on endianness.
95 */
96 static inline uint32_t osmo_jhash(const void *key, uint32_t length, uint32_t initval)
97{
98 uint32_t a, b, c;
99 const uint8_t *k = key;
100
101 /* Set up the internal state */
102 a = b = c = JHASH_INITVAL + length + initval;
103
104 /* All but the last block: affect some 32 bits of (a,b,c) */
105 while (length > 12) {
106 a += osmo_get_unaligned_cpu32(k);
107 b += osmo_get_unaligned_cpu32(k + 4);
108 c += osmo_get_unaligned_cpu32(k + 8);
109 OSMO_JHASH_MIX(a, b, c);
110 length -= 12;
111 k += 12;
112 }
113 /* Last block: affect all 32 bits of (c) */
114 /* All the case statements fall through */
115 switch (length) {
116 case 12: c += (uint32_t)k[11]<<24;
117 case 11: c += (uint32_t)k[10]<<16;
118 case 10: c += (uint32_t)k[9]<<8;
119 case 9: c += k[8];
120 case 8: b += (uint32_t)k[7]<<24;
121 case 7: b += (uint32_t)k[6]<<16;
122 case 6: b += (uint32_t)k[5]<<8;
123 case 5: b += k[4];
124 case 4: a += (uint32_t)k[3]<<24;
125 case 3: a += (uint32_t)k[2]<<16;
126 case 2: a += (uint32_t)k[1]<<8;
127 case 1: a += k[0];
128 OSMO_JHASH_FINAL(a, b, c);
129 case 0: /* Nothing left to add */
130 break;
131 }
132
133 return c;
134}
135
136/* osmo_jhash2 - hash an array of uint32_t's
137 * @k: the key which must be an array of uint32_t's
138 * @length: the number of uint32_t's in the key
139 * @initval: the previous hash, or an arbitray value
140 *
141 * Returns the hash value of the key.
142 */
143 static inline uint32_t osmo_jhash2(const uint32_t *k, uint32_t length, uint32_t initval)
144{
145 uint32_t a, b, c;
146
147 /* Set up the internal state */
148 a = b = c = JHASH_INITVAL + (length<<2) + initval;
149
150 /* Handle most of the key */
151 while (length > 3) {
152 a += k[0];
153 b += k[1];
154 c += k[2];
155 OSMO_JHASH_MIX(a, b, c);
156 length -= 3;
157 k += 3;
158 }
159
160 /* Handle the last 3 uint32_t's: all the case statements fall through */
161 switch (length) {
162 case 3: c += k[2];
163 case 2: b += k[1];
164 case 1: a += k[0];
165 OSMO_JHASH_FINAL(a, b, c);
166 case 0: /* Nothing left to add */
167 break;
168 }
169
170 return c;
171}
bit32gen.h
k
uint8_t k[32]
length
uint8_t length
c
struct abis_rsl_common_hdr c
OSMO_JHASH_MIX
#define OSMO_JHASH_MIX(a, b, c)
Definition: jhash.h:61
osmo_jhash
static uint32_t osmo_jhash(const void *key, uint32_t length, uint32_t initval)
Definition: jhash.h:96
JHASH_INITVAL
#define JHASH_INITVAL
Definition: jhash.h:84
osmo_rol32
static uint32_t osmo_rol32(uint32_t word, unsigned int shift)
rol32 - rotate a 32-bit value left @word: value to rotate @shift: bits to roll
Definition: jhash.h:14
osmo_jhash2
static uint32_t osmo_jhash2(const uint32_t *k, uint32_t length, uint32_t initval)
Definition: jhash.h:143
osmo_get_unaligned_cpu32
static uint32_t osmo_get_unaligned_cpu32(const void *p)
Definition: jhash.h:27
__attribute__
struct osmo_unaligned_cpu32 __attribute__((__packed__))
OSMO_JHASH_FINAL
#define OSMO_JHASH_FINAL(a, b, c)
Definition: jhash.h:72
osmo_unaligned_cpu32
Definition: jhash.h:23
osmo_unaligned_cpu32::x
uint32_t x
Definition: jhash.h:24