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60 lines
1.8 KiB
C
60 lines
1.8 KiB
C
/* jhash.h: Jenkins hash support.
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*
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* Copyright (C) 2006. Bob Jenkins (bob_jenkins@burtleburtle.net)
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*
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* http://burtleburtle.net/bob/hash/
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*
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* These are the credits from Bob's sources:
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*
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* lookup3.c, by Bob Jenkins, May 2006, Public Domain.
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*
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* These are functions for producing 32-bit hashes for hash table lookup.
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* hashword(), hashlittle(), hashlittle2(), hashbig(), mix(), and final()
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* are externally useful functions. Routines to test the hash are included
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* if SELF_TEST is defined. You can use this free for any purpose. It's in
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* the public domain. It has no warranty.
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*
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* Copyright (C) 2009-2010 Jozsef Kadlecsik (kadlec@blackhole.kfki.hu)
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*
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* I've modified Bob's hash to be useful in the Linux kernel, and
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* any bugs present are my fault.
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* Jozsef
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*/
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#ifndef QEMU_JHASH_H
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#define QEMU_JHASH_H
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#include "qemu/bitops.h"
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/*
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* hashtable relation copy from linux kernel jhash
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*/
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/* __jhash_mix -- mix 3 32-bit values reversibly. */
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#define __jhash_mix(a, b, c) \
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{ \
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a -= c; a ^= rol32(c, 4); c += b; \
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b -= a; b ^= rol32(a, 6); a += c; \
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c -= b; c ^= rol32(b, 8); b += a; \
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a -= c; a ^= rol32(c, 16); c += b; \
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b -= a; b ^= rol32(a, 19); a += c; \
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c -= b; c ^= rol32(b, 4); b += a; \
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}
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/* __jhash_final - final mixing of 3 32-bit values (a,b,c) into c */
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#define __jhash_final(a, b, c) \
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{ \
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c ^= b; c -= rol32(b, 14); \
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a ^= c; a -= rol32(c, 11); \
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b ^= a; b -= rol32(a, 25); \
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c ^= b; c -= rol32(b, 16); \
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a ^= c; a -= rol32(c, 4); \
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b ^= a; b -= rol32(a, 14); \
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c ^= b; c -= rol32(b, 24); \
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}
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/* An arbitrary initial parameter */
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#define JHASH_INITVAL 0xdeadbeef
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#endif /* QEMU_JHASH_H */
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