+++ /dev/null
-#ifndef _LINUX_JHASH_H
-#define _LINUX_JHASH_H
-
-/* jhash.h: Jenkins hash support.
- *
- * Copyright (C) 2006. Bob Jenkins (bob_jenkins@burtleburtle.net)
- *
- * http://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
- */
-#include <linux/bitops.h>
-#include <linux/unaligned/packed_struct.h>
-
-/* Best hash sizes are of power of two */
-#define jhash_size(n) ((u32)1<<(n))
-/* Mask the hash value, i.e (value & jhash_mask(n)) instead of (value % n) */
-#define jhash_mask(n) (jhash_size(n)-1)
-
-/* __jhash_mix -- mix 3 32-bit values reversibly. */
-#define __jhash_mix(a, b, c) \
-{ \
- a -= c; a ^= rol32(c, 4); c += b; \
- b -= a; b ^= rol32(a, 6); a += c; \
- c -= b; c ^= rol32(b, 8); b += a; \
- a -= c; a ^= rol32(c, 16); c += b; \
- b -= a; b ^= rol32(a, 19); a += c; \
- c -= b; c ^= rol32(b, 4); b += a; \
-}
-
-/* __jhash_final - final mixing of 3 32-bit values (a,b,c) into c */
-#define __jhash_final(a, b, c) \
-{ \
- c ^= b; c -= rol32(b, 14); \
- a ^= c; a -= rol32(c, 11); \
- b ^= a; b -= rol32(a, 25); \
- c ^= b; c -= rol32(b, 16); \
- a ^= c; a -= rol32(c, 4); \
- b ^= a; b -= rol32(a, 14); \
- c ^= b; c -= rol32(b, 24); \
-}
-
-/* An arbitrary initial parameter */
-#define JHASH_INITVAL 0xdeadbeef
-
-/* 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 u32 jhash(const void *key, u32 length, u32 initval)
-{
- u32 a, b, c;
- const u8 *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 += __get_unaligned_cpu32(k);
- b += __get_unaligned_cpu32(k + 4);
- c += __get_unaligned_cpu32(k + 8);
- __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 += (u32)k[11]<<24;
- case 11: c += (u32)k[10]<<16;
- case 10: c += (u32)k[9]<<8;
- case 9: c += k[8];
- case 8: b += (u32)k[7]<<24;
- case 7: b += (u32)k[6]<<16;
- case 6: b += (u32)k[5]<<8;
- case 5: b += k[4];
- case 4: a += (u32)k[3]<<24;
- case 3: a += (u32)k[2]<<16;
- case 2: a += (u32)k[1]<<8;
- case 1: a += k[0];
- __jhash_final(a, b, c);
- case 0: /* Nothing left to add */
- break;
- }
-
- return c;
-}
-
-/* jhash2 - hash an array of u32's
- * @k: the key which must be an array of u32's
- * @length: the number of u32's in the key
- * @initval: the previous hash, or an arbitray value
- *
- * Returns the hash value of the key.
- */
-static inline u32 jhash2(const u32 *k, u32 length, u32 initval)
-{
- u32 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];
- __jhash_mix(a, b, c);
- length -= 3;
- k += 3;
- }
-
- /* Handle the last 3 u32's: all the case statements fall through */
- switch (length) {
- case 3: c += k[2];
- case 2: b += k[1];
- case 1: a += k[0];
- __jhash_final(a, b, c);
- case 0: /* Nothing left to add */
- break;
- }
-
- return c;
-}
-
-
-/* __jhash_nwords - hash exactly 3, 2 or 1 word(s) */
-static inline u32 __jhash_nwords(u32 a, u32 b, u32 c, u32 initval)
-{
- a += initval;
- b += initval;
- c += initval;
-
- __jhash_final(a, b, c);
-
- return c;
-}
-
-static inline u32 jhash_3words(u32 a, u32 b, u32 c, u32 initval)
-{
- return __jhash_nwords(a, b, c, initval + JHASH_INITVAL + (3 << 2));
-}
-
-static inline u32 jhash_2words(u32 a, u32 b, u32 initval)
-{
- return __jhash_nwords(a, b, 0, initval + JHASH_INITVAL + (2 << 2));
-}
-
-static inline u32 jhash_1word(u32 a, u32 initval)
-{
- return __jhash_nwords(a, 0, 0, initval + JHASH_INITVAL + (1 << 2));
-}
-
-#endif /* _LINUX_JHASH_H */
projects / bcachefs-tools-debian / blobdiff