11da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds#ifndef _LINUX_JHASH_H 21da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds#define _LINUX_JHASH_H 31da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds 41da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds/* jhash.h: Jenkins hash support. 51da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds * 660d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik * Copyright (C) 2006. Bob Jenkins (bob_jenkins@burtleburtle.net) 71da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds * 81da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds * http://burtleburtle.net/bob/hash/ 91da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds * 101da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds * These are the credits from Bob's sources: 111da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds * 1260d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik * lookup3.c, by Bob Jenkins, May 2006, Public Domain. 131da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds * 1460d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik * These are functions for producing 32-bit hashes for hash table lookup. 1560d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik * hashword(), hashlittle(), hashlittle2(), hashbig(), mix(), and final() 1660d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik * are externally useful functions. Routines to test the hash are included 1760d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik * if SELF_TEST is defined. You can use this free for any purpose. It's in 1860d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik * the public domain. It has no warranty. 1960d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik * 2060d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik * Copyright (C) 2009-2010 Jozsef Kadlecsik (kadlec@blackhole.kfki.hu) 211da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds * 221da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds * I've modified Bob's hash to be useful in the Linux kernel, and 2360d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik * any bugs present are my fault. 2460d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik * Jozsef 251da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds */ 2660d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik#include <linux/bitops.h> 2760d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik#include <linux/unaligned/packed_struct.h> 2860d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik 2960d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik/* Best hash sizes are of power of two */ 3060d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik#define jhash_size(n) ((u32)1<<(n)) 3160d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik/* Mask the hash value, i.e (value & jhash_mask(n)) instead of (value % n) */ 3260d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik#define jhash_mask(n) (jhash_size(n)-1) 3360d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik 3460d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik/* __jhash_mix -- mix 3 32-bit values reversibly. */ 3560d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik#define __jhash_mix(a, b, c) \ 3660d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik{ \ 3760d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik a -= c; a ^= rol32(c, 4); c += b; \ 3860d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik b -= a; b ^= rol32(a, 6); a += c; \ 3960d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik c -= b; c ^= rol32(b, 8); b += a; \ 4060d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik a -= c; a ^= rol32(c, 16); c += b; \ 4160d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik b -= a; b ^= rol32(a, 19); a += c; \ 4260d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik c -= b; c ^= rol32(b, 4); b += a; \ 4360d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik} 441da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds 4560d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik/* __jhash_final - final mixing of 3 32-bit values (a,b,c) into c */ 4660d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik#define __jhash_final(a, b, c) \ 4760d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik{ \ 4860d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik c ^= b; c -= rol32(b, 14); \ 4960d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik a ^= c; a -= rol32(c, 11); \ 5060d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik b ^= a; b -= rol32(a, 25); \ 5160d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik c ^= b; c -= rol32(b, 16); \ 5260d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik a ^= c; a -= rol32(c, 4); \ 5360d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik b ^= a; b -= rol32(a, 14); \ 5460d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik c ^= b; c -= rol32(b, 24); \ 551da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds} 561da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds 5760d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik/* An arbitrary initial parameter */ 5860d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik#define JHASH_INITVAL 0xdeadbeef 591da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds 6060d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik/* jhash - hash an arbitrary key 6160d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik * @k: sequence of bytes as key 6260d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik * @length: the length of the key 6360d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik * @initval: the previous hash, or an arbitray value 6460d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik * 6560d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik * The generic version, hashes an arbitrary sequence of bytes. 6660d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik * No alignment or length assumptions are made about the input key. 6760d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik * 6860d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik * Returns the hash value of the key. The result depends on endianness. 691da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds */ 701da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvaldsstatic inline u32 jhash(const void *key, u32 length, u32 initval) 711da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds{ 7260d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik u32 a, b, c; 731da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds const u8 *k = key; 741da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds 7560d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik /* Set up the internal state */ 7660d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik a = b = c = JHASH_INITVAL + length + initval; 771da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds 7860d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik /* All but the last block: affect some 32 bits of (a,b,c) */ 7960d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik while (length > 12) { 8060d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik a += __get_unaligned_cpu32(k); 8160d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik b += __get_unaligned_cpu32(k + 4); 8260d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik c += __get_unaligned_cpu32(k + 8); 8360d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik __jhash_mix(a, b, c); 8460d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik length -= 12; 851da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds k += 12; 861da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds } 8760d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik /* Last block: affect all 32 bits of (c) */ 8860d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik /* All the case statements fall through */ 8960d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik switch (length) { 9060d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik case 12: c += (u32)k[11]<<24; 9160d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik case 11: c += (u32)k[10]<<16; 9260d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik case 10: c += (u32)k[9]<<8; 9360d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik case 9: c += k[8]; 9460d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik case 8: b += (u32)k[7]<<24; 9560d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik case 7: b += (u32)k[6]<<16; 9660d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik case 6: b += (u32)k[5]<<8; 9760d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik case 5: b += k[4]; 9860d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik case 4: a += (u32)k[3]<<24; 9960d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik case 3: a += (u32)k[2]<<16; 10060d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik case 2: a += (u32)k[1]<<8; 10160d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik case 1: a += k[0]; 10260d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik __jhash_final(a, b, c); 10360d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik case 0: /* Nothing left to add */ 10460d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik break; 10560d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik } 1061da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds 1071da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds return c; 1081da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds} 1091da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds 11060d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik/* jhash2 - hash an array of u32's 11160d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik * @k: the key which must be an array of u32's 11260d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik * @length: the number of u32's in the key 11360d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik * @initval: the previous hash, or an arbitray value 11460d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik * 11560d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik * Returns the hash value of the key. 1161da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds */ 1178e87e014ec881ce353e1f43340157f519b5d9f30Patrick McHardystatic inline u32 jhash2(const u32 *k, u32 length, u32 initval) 1181da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds{ 11960d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik u32 a, b, c; 1201da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds 12160d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik /* Set up the internal state */ 12260d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik a = b = c = JHASH_INITVAL + (length<<2) + initval; 1231da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds 12460d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik /* Handle most of the key */ 12560d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik while (length > 3) { 1261da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds a += k[0]; 1271da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds b += k[1]; 1281da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds c += k[2]; 1291da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds __jhash_mix(a, b, c); 13060d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik length -= 3; 13160d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik k += 3; 1321da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds } 1331da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds 13460d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik /* Handle the last 3 u32's: all the case statements fall through */ 13560d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik switch (length) { 13660d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik case 3: c += k[2]; 13760d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik case 2: b += k[1]; 13860d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik case 1: a += k[0]; 13960d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik __jhash_final(a, b, c); 14060d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik case 0: /* Nothing left to add */ 14160d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik break; 14260d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik } 1431da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds 1441da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds return c; 1451da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds} 1461da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds 1471da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds 14860d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik/* jhash_3words - hash exactly 3, 2 or 1 word(s) */ 1491da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvaldsstatic inline u32 jhash_3words(u32 a, u32 b, u32 c, u32 initval) 1501da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds{ 15160d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik a += JHASH_INITVAL; 15260d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik b += JHASH_INITVAL; 1531da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds c += initval; 1541da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds 15560d509c823cca21e77d537bd356785f7cfe8f0d1Jozsef Kadlecsik __jhash_final(a, b, c); 1561da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds 1571da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds return c; 1581da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds} 1591da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds 1601da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvaldsstatic inline u32 jhash_2words(u32 a, u32 b, u32 initval) 1611da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds{ 1621da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds return jhash_3words(a, b, 0, initval); 1631da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds} 1641da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds 1651da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvaldsstatic inline u32 jhash_1word(u32 a, u32 initval) 1661da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds{ 1671da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds return jhash_3words(a, 0, 0, initval); 1681da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds} 1691da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds 1701da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds#endif /* _LINUX_JHASH_H */ 171