#ifndef _LINUX_JHASH_H
#define _LINUX_JHASH_H
-/* jhash.c: Jenkins hash support.
+
+/* jhash.h: Jenkins hash support.
*
* Copyright (C) 2006. Bob Jenkins (bob_jenkins@burtleburtle.net)
*
* 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
+ * 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. The generic jhash is left out intentionally.
+ * any bugs present are my fault.
* Jozsef
*/
-#ifdef __KERNEL__
-#include <asm/byteorder.h>
+#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_rot - rotate 32 bit */
-#define __jhash_rot(x,k) (((x)<<(k)) | ((x)>>(32-(k))))
-
/* __jhash_mix -- mix 3 32-bit values reversibly. */
-#define __jhash_mix(a,b,c) \
+#define __jhash_mix(a, b, c) \
{ \
- a -= c; a ^= __jhash_rot(c, 4); c += b; \
- b -= a; b ^= __jhash_rot(a, 6); a += c; \
- c -= b; c ^= __jhash_rot(b, 8); b += a; \
- a -= c; a ^= __jhash_rot(c,16); c += b; \
- b -= a; b ^= __jhash_rot(a,19); a += c; \
- c -= b; c ^= __jhash_rot(b, 4); b += a; \
+ 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) \
+#define __jhash_final(a, b, c) \
{ \
- c ^= b; c -= __jhash_rot(b,14); \
- a ^= c; a -= __jhash_rot(c,11); \
- b ^= a; b -= __jhash_rot(a,25); \
- c ^= b; c -= __jhash_rot(b,16); \
- a ^= c; a -= __jhash_rot(c,4); \
- b ^= a; b -= __jhash_rot(a,14); \
- c ^= b; c -= __jhash_rot(b,24); \
+ 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
a += k[0];
b += k[1];
c += k[2];
- __jhash_mix(a,b,c);
+ __jhash_mix(a, b, c);
length -= 3;
k += 3;
}
-
+
/* Handle the last 3 u32's: all the case statements fall through */
- switch(length) {
+ switch (length) {
case 3: c += k[2];
case 2: b += k[1];
case 1: a += k[0];
- __jhash_final(a,b,c);
+ __jhash_final(a, b, c);
case 0: /* Nothing left to add */
break;
}
b += JHASH_INITVAL;
c += initval;
- __jhash_final(a,b,c);
-
+ __jhash_final(a, b, c);
+
return c;
}
+
static inline u32 jhash_2words(u32 a, u32 b, u32 initval)
{
return jhash_3words(a, b, 0, initval);
static inline u32 jhash_1word(u32 a, u32 initval)
{
- return jhash_3words(a, 0, 0, initval);
+ return jhash_3words(a, 0, 0, initval);
}
-#endif /* __KERNEL__ */
-
#endif /* _LINUX_JHASH_H */
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