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jhash.h
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#pragma once
#include <osmocom/core/bit32gen.h>
/* Below is a partial copy of
* https://raw.githubusercontent.com/torvalds/linux/3eb3c33c1d87029a3832e205eebd59cfb56ba3a4/tools/include/linux/bitops.h
* with an osmo_ prefix applied to avoid any collisions.
*/
/* SPDX-License-Identifier: GPL-2.0 */
static inline uint32_t osmo_rol32(uint32_t word, unsigned int shift)
{
return (word << shift) | (word >> ((-shift) & 31));
}
/* Below is a partial copy of
* https://raw.githubusercontent.com/torvalds/linux/22c033989c3eb9731ad0c497dfab4231b8e367d6/include/linux/unaligned/packed_struct.h
* with an osmo_ prefix applied to avoid any collisions.
*/
struct osmo_unaligned_cpu32 {
uint32_t x;
} __attribute__((__packed__));
static inline uint32_t osmo_get_unaligned_cpu32(const void *p)
{
const struct osmo_unaligned_cpu32 *ptr = (const struct osmo_unaligned_cpu32 *)p;
return ptr->x;
}
/* Below is a partial copy of
* https://raw.githubusercontent.com/torvalds/linux/79e3ea5aab48c83de9410e43b52895406847eca7/tools/include/linux/jhash.h
* with an osmo_ prefix applied to avoid any collisions.
*/
/* jhash.h: Jenkins hash support.
*
* Copyright (C) 2006. Bob Jenkins (bob_jenkins@burtleburtle.net)
*
* https://burtleburtle.net/bob/hash/
*
* These are the credits from Bob's sources:
*
* 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.
*
* Copyright (C) 2009-2010 Jozsef Kadlecsik (kadlec@blackhole.kfki.hu)
*
* I've modified Bob's hash to be useful in the Linux kernel, and
* any bugs present are my fault.
* Jozsef
*/
/* OSMO_JHASH_MIX -- mix 3 32-bit values reversibly. */
#define OSMO_JHASH_MIX(a, b, c) \
{ \
a -= c; a ^= osmo_rol32(c, 4); c += b; \
b -= a; b ^= osmo_rol32(a, 6); a += c; \
c -= b; c ^= osmo_rol32(b, 8); b += a; \
a -= c; a ^= osmo_rol32(c, 16); c += b; \
b -= a; b ^= osmo_rol32(a, 19); a += c; \
c -= b; c ^= osmo_rol32(b, 4); b += a; \
}
/* OSMO_JHASH_FINAL - final mixing of 3 32-bit values (a,b,c) into c */
#define OSMO_JHASH_FINAL(a, b, c) \
{ \
c ^= b; c -= osmo_rol32(b, 14); \
a ^= c; a -= osmo_rol32(c, 11); \
b ^= a; b -= osmo_rol32(a, 25); \
c ^= b; c -= osmo_rol32(b, 16); \
a ^= c; a -= osmo_rol32(c, 4); \
b ^= a; b -= osmo_rol32(a, 14); \
c ^= b; c -= osmo_rol32(b, 24); \
}
/* An arbitrary initial parameter */
#define JHASH_INITVAL 0xdeadbeef
/* osmo_jhash - hash an arbitrary key
* @k: sequence of bytes as key
* @length: the length of the key
* @initval: the previous hash, or an arbitray value
*
* The generic version, hashes an arbitrary sequence of bytes.
* No alignment or length assumptions are made about the input key.
*
* Returns the hash value of the key. The result depends on endianness.
*/
static inline uint32_t osmo_jhash(const void *key, uint32_t length, uint32_t initval)
{
uint32_t a, b, c;
const uint8_t *k = key;
/* Set up the internal state */
a = b = c = JHASH_INITVAL + length + initval;
/* All but the last block: affect some 32 bits of (a,b,c) */
while (length > 12) {
a += osmo_get_unaligned_cpu32(k);
b += osmo_get_unaligned_cpu32(k + 4);
c += osmo_get_unaligned_cpu32(k + 8);
OSMO_JHASH_MIX(a, b, c);
length -= 12;
k += 12;
}
/* Last block: affect all 32 bits of (c) */
/* All the case statements fall through */
switch (length) {
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];
OSMO_JHASH_FINAL(a, b, c);
case 0: /* Nothing left to add */
break;
}
return c;
}
/* osmo_jhash2 - hash an array of uint32_t's
* @k: the key which must be an array of uint32_t's
* @length: the number of uint32_t's in the key
* @initval: the previous hash, or an arbitray value
*
* Returns the hash value of the key.
*/
static inline uint32_t osmo_jhash2(const uint32_t *k, uint32_t length, uint32_t initval)
{
uint32_t a, b, c;
/* Set up the internal state */
a = b = c = JHASH_INITVAL + (length<<2) + initval;
/* Handle most of the key */
while (length > 3) {
a += k[0];
b += k[1];
c += k[2];
OSMO_JHASH_MIX(a, b, c);
length -= 3;
k += 3;
}
/* Handle the last 3 uint32_t's: all the case statements fall through */
switch (length) {
case 3: c += k[2];
case 2: b += k[1];
case 1: a += k[0];
OSMO_JHASH_FINAL(a, b, c);
case 0: /* Nothing left to add */
break;
}
return c;
}
bit32gen.h
__attribute__
enum gsm0808_assignment_requirement __attribute__
Definition log2.h:61
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
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