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#ifndef _LINUX_JHASH_H
#define _LINUX_JHASH_H
/* jhash.h: Jenkins hash support.
*
* Copyright (C) 2006. Bob Jenkins (bob_jenkins@burtleburtle.net)
* Copyright (c) 2013 Qualcomm Atheros, Inc.
*
* 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); \
}
/* An arbitrary initial parameter */
#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 */