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Diffstat (limited to 'kernel/include/linux/netfilter/ip_set_jhash.h')
| -rw-r--r-- | kernel/include/linux/netfilter/ip_set_jhash.h | 157 |
1 files changed, 157 insertions, 0 deletions
diff --git a/kernel/include/linux/netfilter/ip_set_jhash.h b/kernel/include/linux/netfilter/ip_set_jhash.h new file mode 100644 index 0000000..2000b9f --- /dev/null +++ b/kernel/include/linux/netfilter/ip_set_jhash.h @@ -0,0 +1,157 @@ +#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 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 + */ + +#define __rot(x,k) (((x)<<(k)) | ((x)>>(32-(k)))) + +/* __jhash_mix - mix 3 32-bit values reversibly. */ +#define __jhash_mix(a,b,c) \ +{ \ + a -= c; a ^= __rot(c, 4); c += b; \ + b -= a; b ^= __rot(a, 6); a += c; \ + c -= b; c ^= __rot(b, 8); b += a; \ + a -= c; a ^= __rot(c,16); c += b; \ + b -= a; b ^= __rot(a,19); a += c; \ + c -= b; c ^= __rot(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 -= __rot(b,14); \ + a ^= c; a -= __rot(c,11); \ + b ^= a; b -= __rot(a,25); \ + c ^= b; c -= __rot(b,16); \ + a ^= c; a -= __rot(c,4); \ + b ^= a; b -= __rot(a,14); \ + c ^= b; c -= __rot(b,24); \ +} + +/* The golden ration: an arbitrary value */ +#define JHASH_GOLDEN_RATIO 0xdeadbeef + +/* The most generic version, hashes an arbitrary sequence + * of bytes. No alignment or length assumptions are made about + * the input 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_GOLDEN_RATIO + length + initval; + + /* all but the last block: affect some 32 bits of (a,b,c) */ + while (length > 12) { + a += (k[0] + ((u32)k[1]<<8) + ((u32)k[2]<<16) + ((u32)k[3]<<24)); + b += (k[4] + ((u32)k[5]<<8) + ((u32)k[6]<<16) + ((u32)k[7]<<24)); + c += (k[8] + ((u32)k[9]<<8) + ((u32)k[10]<<16) + ((u32)k[11]<<24)); + __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 : + break; + } + + return c; +} + +/* A special optimized version that handles 1 or more of u32s. + * The length parameter here is the number of u32s in 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_GOLDEN_RATIO + (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: /* case 0: nothing left to add */ + break; + } + + return c; +} + +/* A special ultra-optimized versions that knows they are hashing exactly + * 3, 2 or 1 word(s). + */ +static inline u32 jhash_3words(u32 a, u32 b, u32 c, u32 initval) +{ + a += JHASH_GOLDEN_RATIO + initval; + b += JHASH_GOLDEN_RATIO + initval; + c += JHASH_GOLDEN_RATIO + initval; + + __jhash_final(a, b, c); + + return c; +} + +static inline u32 jhash_2words(u32 a, u32 b, u32 initval) +{ + return jhash_3words(0, a, b, initval); +} + +static inline u32 jhash_1word(u32 a, u32 initval) +{ + return jhash_3words(0, 0, a, initval); +} + +#endif /* _LINUX_JHASH_H */ |