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603 lines
18 KiB
603 lines
18 KiB
/*
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* $Id: linkhash.c,v 1.4 2006/01/26 02:16:28 mclark Exp $
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*
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* Copyright (c) 2004, 2005 Metaparadigm Pte. Ltd.
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* Michael Clark <michael@metaparadigm.com>
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* Copyright (c) 2009 Hewlett-Packard Development Company, L.P.
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*
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* This library is free software; you can redistribute it and/or modify
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* it under the terms of the MIT license. See COPYING for details.
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*
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*/
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#include <stdio.h>
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#include <string.h>
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#include <stdlib.h>
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#include <stdarg.h>
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#include <stddef.h>
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#include <limits.h>
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#ifdef HAVE_ENDIAN_H
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# include <endian.h> /* attempt to define endianness */
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#endif
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#include "random_seed.h"
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#include "linkhash.h"
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void lh_abort(const char *msg, ...)
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{
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va_list ap;
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va_start(ap, msg);
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vprintf(msg, ap);
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va_end(ap);
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exit(1);
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}
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unsigned long lh_ptr_hash(const void *k)
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{
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/* CAW: refactored to be 64bit nice */
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return (unsigned long)((((ptrdiff_t)k * LH_PRIME) >> 4) & ULONG_MAX);
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}
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int lh_ptr_equal(const void *k1, const void *k2)
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{
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return (k1 == k2);
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}
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/*
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* hashlittle from lookup3.c, by Bob Jenkins, May 2006, Public Domain.
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* http://burtleburtle.net/bob/c/lookup3.c
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* minor modifications to make functions static so no symbols are exported
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* minor mofifications to compile with -Werror
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*/
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/*
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-------------------------------------------------------------------------------
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lookup3.c, by Bob Jenkins, May 2006, Public Domain.
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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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You probably want to use hashlittle(). hashlittle() and hashbig()
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hash byte arrays. hashlittle() is is faster than hashbig() on
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little-endian machines. Intel and AMD are little-endian machines.
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On second thought, you probably want hashlittle2(), which is identical to
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hashlittle() except it returns two 32-bit hashes for the price of one.
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You could implement hashbig2() if you wanted but I haven't bothered here.
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If you want to find a hash of, say, exactly 7 integers, do
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a = i1; b = i2; c = i3;
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mix(a,b,c);
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a += i4; b += i5; c += i6;
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mix(a,b,c);
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a += i7;
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final(a,b,c);
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then use c as the hash value. If you have a variable length array of
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4-byte integers to hash, use hashword(). If you have a byte array (like
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a character string), use hashlittle(). If you have several byte arrays, or
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a mix of things, see the comments above hashlittle().
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Why is this so big? I read 12 bytes at a time into 3 4-byte integers,
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then mix those integers. This is fast (you can do a lot more thorough
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mixing with 12*3 instructions on 3 integers than you can with 3 instructions
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on 1 byte), but shoehorning those bytes into integers efficiently is messy.
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-------------------------------------------------------------------------------
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*/
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/*
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* My best guess at if you are big-endian or little-endian. This may
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* need adjustment.
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*/
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#if (defined(__BYTE_ORDER) && defined(__LITTLE_ENDIAN) && \
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__BYTE_ORDER == __LITTLE_ENDIAN) || \
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(defined(i386) || defined(__i386__) || defined(__i486__) || \
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defined(__i586__) || defined(__i686__) || defined(vax) || defined(MIPSEL))
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# define HASH_LITTLE_ENDIAN 1
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# define HASH_BIG_ENDIAN 0
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#elif (defined(__BYTE_ORDER) && defined(__BIG_ENDIAN) && \
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__BYTE_ORDER == __BIG_ENDIAN) || \
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(defined(sparc) || defined(POWERPC) || defined(mc68000) || defined(sel))
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# define HASH_LITTLE_ENDIAN 0
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# define HASH_BIG_ENDIAN 1
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#else
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# define HASH_LITTLE_ENDIAN 0
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# define HASH_BIG_ENDIAN 0
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#endif
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#define hashsize(n) ((uint32_t)1<<(n))
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#define hashmask(n) (hashsize(n)-1)
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#define rot(x,k) (((x)<<(k)) | ((x)>>(32-(k))))
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/*
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-------------------------------------------------------------------------------
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mix -- mix 3 32-bit values reversibly.
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This is reversible, so any information in (a,b,c) before mix() is
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still in (a,b,c) after mix().
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If four pairs of (a,b,c) inputs are run through mix(), or through
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mix() in reverse, there are at least 32 bits of the output that
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are sometimes the same for one pair and different for another pair.
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This was tested for:
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* pairs that differed by one bit, by two bits, in any combination
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of top bits of (a,b,c), or in any combination of bottom bits of
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(a,b,c).
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* "differ" is defined as +, -, ^, or ~^. For + and -, I transformed
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the output delta to a Gray code (a^(a>>1)) so a string of 1's (as
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is commonly produced by subtraction) look like a single 1-bit
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difference.
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* the base values were pseudorandom, all zero but one bit set, or
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all zero plus a counter that starts at zero.
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Some k values for my "a-=c; a^=rot(c,k); c+=b;" arrangement that
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satisfy this are
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4 6 8 16 19 4
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9 15 3 18 27 15
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14 9 3 7 17 3
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Well, "9 15 3 18 27 15" didn't quite get 32 bits diffing
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for "differ" defined as + with a one-bit base and a two-bit delta. I
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used http://burtleburtle.net/bob/hash/avalanche.html to choose
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the operations, constants, and arrangements of the variables.
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This does not achieve avalanche. There are input bits of (a,b,c)
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that fail to affect some output bits of (a,b,c), especially of a. The
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most thoroughly mixed value is c, but it doesn't really even achieve
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avalanche in c.
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This allows some parallelism. Read-after-writes are good at doubling
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the number of bits affected, so the goal of mixing pulls in the opposite
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direction as the goal of parallelism. I did what I could. Rotates
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seem to cost as much as shifts on every machine I could lay my hands
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on, and rotates are much kinder to the top and bottom bits, so I used
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rotates.
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-------------------------------------------------------------------------------
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*/
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#define mix(a,b,c) \
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{ \
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a -= c; a ^= rot(c, 4); c += b; \
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b -= a; b ^= rot(a, 6); a += c; \
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c -= b; c ^= rot(b, 8); b += a; \
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a -= c; a ^= rot(c,16); c += b; \
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b -= a; b ^= rot(a,19); a += c; \
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c -= b; c ^= rot(b, 4); b += a; \
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}
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/*
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-------------------------------------------------------------------------------
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final -- final mixing of 3 32-bit values (a,b,c) into c
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Pairs of (a,b,c) values differing in only a few bits will usually
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produce values of c that look totally different. This was tested for
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* pairs that differed by one bit, by two bits, in any combination
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of top bits of (a,b,c), or in any combination of bottom bits of
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(a,b,c).
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* "differ" is defined as +, -, ^, or ~^. For + and -, I transformed
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the output delta to a Gray code (a^(a>>1)) so a string of 1's (as
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is commonly produced by subtraction) look like a single 1-bit
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difference.
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* the base values were pseudorandom, all zero but one bit set, or
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all zero plus a counter that starts at zero.
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These constants passed:
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14 11 25 16 4 14 24
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12 14 25 16 4 14 24
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and these came close:
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4 8 15 26 3 22 24
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10 8 15 26 3 22 24
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11 8 15 26 3 22 24
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-------------------------------------------------------------------------------
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*/
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#define final(a,b,c) \
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{ \
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c ^= b; c -= rot(b,14); \
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a ^= c; a -= rot(c,11); \
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b ^= a; b -= rot(a,25); \
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c ^= b; c -= rot(b,16); \
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a ^= c; a -= rot(c,4); \
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b ^= a; b -= rot(a,14); \
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c ^= b; c -= rot(b,24); \
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}
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/*
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-------------------------------------------------------------------------------
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hashlittle() -- hash a variable-length key into a 32-bit value
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k : the key (the unaligned variable-length array of bytes)
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length : the length of the key, counting by bytes
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initval : can be any 4-byte value
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Returns a 32-bit value. Every bit of the key affects every bit of
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the return value. Two keys differing by one or two bits will have
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totally different hash values.
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The best hash table sizes are powers of 2. There is no need to do
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mod a prime (mod is sooo slow!). If you need less than 32 bits,
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use a bitmask. For example, if you need only 10 bits, do
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h = (h & hashmask(10));
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In which case, the hash table should have hashsize(10) elements.
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If you are hashing n strings (uint8_t **)k, do it like this:
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for (i=0, h=0; i<n; ++i) h = hashlittle( k[i], len[i], h);
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By Bob Jenkins, 2006. bob_jenkins@burtleburtle.net. You may use this
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code any way you wish, private, educational, or commercial. It's free.
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Use for hash table lookup, or anything where one collision in 2^^32 is
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acceptable. Do NOT use for cryptographic purposes.
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-------------------------------------------------------------------------------
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*/
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static uint32_t hashlittle( const void *key, size_t length, uint32_t initval)
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{
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uint32_t a,b,c; /* internal state */
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union { const void *ptr; size_t i; } u; /* needed for Mac Powerbook G4 */
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/* Set up the internal state */
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a = b = c = 0xdeadbeef + ((uint32_t)length) + initval;
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u.ptr = key;
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if (HASH_LITTLE_ENDIAN && ((u.i & 0x3) == 0)) {
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const uint32_t *k = (const uint32_t *)key; /* read 32-bit chunks */
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/*------ all but last block: aligned reads and affect 32 bits of (a,b,c) */
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while (length > 12)
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{
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a += k[0];
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b += k[1];
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c += k[2];
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mix(a,b,c);
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length -= 12;
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k += 3;
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}
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/*----------------------------- handle the last (probably partial) block */
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/*
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* "k[2]&0xffffff" actually reads beyond the end of the string, but
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* then masks off the part it's not allowed to read. Because the
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* string is aligned, the masked-off tail is in the same word as the
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* rest of the string. Every machine with memory protection I've seen
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* does it on word boundaries, so is OK with this. But VALGRIND will
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* still catch it and complain. The masking trick does make the hash
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* noticably faster for short strings (like English words).
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*/
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#ifndef VALGRIND
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switch(length)
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{
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case 12: c+=k[2]; b+=k[1]; a+=k[0]; break;
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case 11: c+=k[2]&0xffffff; b+=k[1]; a+=k[0]; break;
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case 10: c+=k[2]&0xffff; b+=k[1]; a+=k[0]; break;
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case 9 : c+=k[2]&0xff; b+=k[1]; a+=k[0]; break;
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case 8 : b+=k[1]; a+=k[0]; break;
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case 7 : b+=k[1]&0xffffff; a+=k[0]; break;
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case 6 : b+=k[1]&0xffff; a+=k[0]; break;
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case 5 : b+=k[1]&0xff; a+=k[0]; break;
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case 4 : a+=k[0]; break;
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case 3 : a+=k[0]&0xffffff; break;
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case 2 : a+=k[0]&0xffff; break;
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case 1 : a+=k[0]&0xff; break;
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case 0 : return c; /* zero length strings require no mixing */
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}
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#else /* make valgrind happy */
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const uint8_t *k8 = (const uint8_t *)k;
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switch(length)
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{
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case 12: c+=k[2]; b+=k[1]; a+=k[0]; break;
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case 11: c+=((uint32_t)k8[10])<<16; /* fall through */
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case 10: c+=((uint32_t)k8[9])<<8; /* fall through */
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case 9 : c+=k8[8]; /* fall through */
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case 8 : b+=k[1]; a+=k[0]; break;
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case 7 : b+=((uint32_t)k8[6])<<16; /* fall through */
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case 6 : b+=((uint32_t)k8[5])<<8; /* fall through */
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case 5 : b+=k8[4]; /* fall through */
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case 4 : a+=k[0]; break;
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case 3 : a+=((uint32_t)k8[2])<<16; /* fall through */
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case 2 : a+=((uint32_t)k8[1])<<8; /* fall through */
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case 1 : a+=k8[0]; break;
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case 0 : return c;
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}
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#endif /* !valgrind */
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} else if (HASH_LITTLE_ENDIAN && ((u.i & 0x1) == 0)) {
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const uint16_t *k = (const uint16_t *)key; /* read 16-bit chunks */
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const uint8_t *k8;
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/*--------------- all but last block: aligned reads and different mixing */
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while (length > 12)
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{
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a += k[0] + (((uint32_t)k[1])<<16);
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b += k[2] + (((uint32_t)k[3])<<16);
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c += k[4] + (((uint32_t)k[5])<<16);
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mix(a,b,c);
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length -= 12;
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k += 6;
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}
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/*----------------------------- handle the last (probably partial) block */
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k8 = (const uint8_t *)k;
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switch(length)
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{
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case 12: c+=k[4]+(((uint32_t)k[5])<<16);
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b+=k[2]+(((uint32_t)k[3])<<16);
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a+=k[0]+(((uint32_t)k[1])<<16);
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break;
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case 11: c+=((uint32_t)k8[10])<<16; /* fall through */
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case 10: c+=k[4];
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b+=k[2]+(((uint32_t)k[3])<<16);
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a+=k[0]+(((uint32_t)k[1])<<16);
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break;
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case 9 : c+=k8[8]; /* fall through */
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case 8 : b+=k[2]+(((uint32_t)k[3])<<16);
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a+=k[0]+(((uint32_t)k[1])<<16);
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break;
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case 7 : b+=((uint32_t)k8[6])<<16; /* fall through */
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case 6 : b+=k[2];
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a+=k[0]+(((uint32_t)k[1])<<16);
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break;
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case 5 : b+=k8[4]; /* fall through */
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case 4 : a+=k[0]+(((uint32_t)k[1])<<16);
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break;
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case 3 : a+=((uint32_t)k8[2])<<16; /* fall through */
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case 2 : a+=k[0];
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break;
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case 1 : a+=k8[0];
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break;
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case 0 : return c; /* zero length requires no mixing */
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}
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} else { /* need to read the key one byte at a time */
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const uint8_t *k = (const uint8_t *)key;
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/*--------------- all but the last block: affect some 32 bits of (a,b,c) */
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while (length > 12)
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{
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a += k[0];
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a += ((uint32_t)k[1])<<8;
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a += ((uint32_t)k[2])<<16;
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a += ((uint32_t)k[3])<<24;
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b += k[4];
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b += ((uint32_t)k[5])<<8;
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b += ((uint32_t)k[6])<<16;
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b += ((uint32_t)k[7])<<24;
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c += k[8];
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c += ((uint32_t)k[9])<<8;
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c += ((uint32_t)k[10])<<16;
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c += ((uint32_t)k[11])<<24;
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mix(a,b,c);
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length -= 12;
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k += 12;
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}
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/*-------------------------------- last block: affect all 32 bits of (c) */
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switch(length) /* all the case statements fall through */
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{
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case 12: c+=((uint32_t)k[11])<<24;
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case 11: c+=((uint32_t)k[10])<<16;
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case 10: c+=((uint32_t)k[9])<<8;
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case 9 : c+=k[8];
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case 8 : b+=((uint32_t)k[7])<<24;
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case 7 : b+=((uint32_t)k[6])<<16;
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case 6 : b+=((uint32_t)k[5])<<8;
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case 5 : b+=k[4];
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case 4 : a+=((uint32_t)k[3])<<24;
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case 3 : a+=((uint32_t)k[2])<<16;
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case 2 : a+=((uint32_t)k[1])<<8;
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case 1 : a+=k[0];
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break;
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case 0 : return c;
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}
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}
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final(a,b,c);
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return c;
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}
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unsigned long lh_char_hash(const void *k)
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{
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static volatile int random_seed = -1;
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if (random_seed == -1) {
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int seed;
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/* we can't use -1 as it is the unitialized sentinel */
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while ((seed = json_c_get_random_seed()) == -1);
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#if defined __GNUC__
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__sync_val_compare_and_swap(&random_seed, -1, seed);
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#elif defined _MSC_VER
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InterlockedCompareExchange(&random_seed, seed, -1);
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#else
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#warning "racy random seed initializtion if used by multiple threads"
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random_seed = seed; /* potentially racy */
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#endif
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}
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return hashlittle((const char*)k, strlen((const char*)k), random_seed);
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}
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int lh_char_equal(const void *k1, const void *k2)
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{
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return (strcmp((const char*)k1, (const char*)k2) == 0);
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}
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struct lh_table* lh_table_new(int size, const char *name,
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lh_entry_free_fn *free_fn,
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lh_hash_fn *hash_fn,
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lh_equal_fn *equal_fn)
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{
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int i;
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struct lh_table *t;
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t = (struct lh_table*)calloc(1, sizeof(struct lh_table));
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if(!t) lh_abort("lh_table_new: calloc failed\n");
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t->count = 0;
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t->size = size;
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t->name = name;
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t->table = (struct lh_entry*)calloc(size, sizeof(struct lh_entry));
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if(!t->table) lh_abort("lh_table_new: calloc failed\n");
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t->free_fn = free_fn;
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t->hash_fn = hash_fn;
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t->equal_fn = equal_fn;
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for(i = 0; i < size; i++) t->table[i].k = LH_EMPTY;
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return t;
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}
|
|
|
|
struct lh_table* lh_kchar_table_new(int size, const char *name,
|
|
lh_entry_free_fn *free_fn)
|
|
{
|
|
return lh_table_new(size, name, free_fn, lh_char_hash, lh_char_equal);
|
|
}
|
|
|
|
struct lh_table* lh_kptr_table_new(int size, const char *name,
|
|
lh_entry_free_fn *free_fn)
|
|
{
|
|
return lh_table_new(size, name, free_fn, lh_ptr_hash, lh_ptr_equal);
|
|
}
|
|
|
|
void lh_table_resize(struct lh_table *t, int new_size)
|
|
{
|
|
struct lh_table *new_t;
|
|
struct lh_entry *ent;
|
|
|
|
new_t = lh_table_new(new_size, t->name, NULL, t->hash_fn, t->equal_fn);
|
|
ent = t->head;
|
|
while(ent) {
|
|
lh_table_insert(new_t, ent->k, ent->v);
|
|
ent = ent->next;
|
|
}
|
|
free(t->table);
|
|
t->table = new_t->table;
|
|
t->size = new_size;
|
|
t->head = new_t->head;
|
|
t->tail = new_t->tail;
|
|
t->resizes++;
|
|
free(new_t);
|
|
}
|
|
|
|
void lh_table_free(struct lh_table *t)
|
|
{
|
|
struct lh_entry *c;
|
|
for(c = t->head; c != NULL; c = c->next) {
|
|
if(t->free_fn) {
|
|
t->free_fn(c);
|
|
}
|
|
}
|
|
free(t->table);
|
|
free(t);
|
|
}
|
|
|
|
|
|
int lh_table_insert(struct lh_table *t, void *k, const void *v)
|
|
{
|
|
unsigned long h, n;
|
|
|
|
t->inserts++;
|
|
if(t->count >= t->size * LH_LOAD_FACTOR) lh_table_resize(t, t->size * 2);
|
|
|
|
h = t->hash_fn(k);
|
|
n = h % t->size;
|
|
|
|
while( 1 ) {
|
|
if(t->table[n].k == LH_EMPTY || t->table[n].k == LH_FREED) break;
|
|
t->collisions++;
|
|
if ((int)++n == t->size) n = 0;
|
|
}
|
|
|
|
t->table[n].k = k;
|
|
t->table[n].v = v;
|
|
t->count++;
|
|
|
|
if(t->head == NULL) {
|
|
t->head = t->tail = &t->table[n];
|
|
t->table[n].next = t->table[n].prev = NULL;
|
|
} else {
|
|
t->tail->next = &t->table[n];
|
|
t->table[n].prev = t->tail;
|
|
t->table[n].next = NULL;
|
|
t->tail = &t->table[n];
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
struct lh_entry* lh_table_lookup_entry(struct lh_table *t, const void *k)
|
|
{
|
|
unsigned long h = t->hash_fn(k);
|
|
unsigned long n = h % t->size;
|
|
int count = 0;
|
|
|
|
t->lookups++;
|
|
while( count < t->size ) {
|
|
if(t->table[n].k == LH_EMPTY) return NULL;
|
|
if(t->table[n].k != LH_FREED &&
|
|
t->equal_fn(t->table[n].k, k)) return &t->table[n];
|
|
if ((int)++n == t->size) n = 0;
|
|
count++;
|
|
}
|
|
return NULL;
|
|
}
|
|
|
|
|
|
const void* lh_table_lookup(struct lh_table *t, const void *k)
|
|
{
|
|
void *result;
|
|
lh_table_lookup_ex(t, k, &result);
|
|
return result;
|
|
}
|
|
|
|
json_bool lh_table_lookup_ex(struct lh_table* t, const void* k, void **v)
|
|
{
|
|
struct lh_entry *e = lh_table_lookup_entry(t, k);
|
|
if (e != NULL) {
|
|
if (v != NULL) *v = (void *)e->v;
|
|
return TRUE; /* key found */
|
|
}
|
|
if (v != NULL) *v = NULL;
|
|
return FALSE; /* key not found */
|
|
}
|
|
|
|
int lh_table_delete_entry(struct lh_table *t, struct lh_entry *e)
|
|
{
|
|
ptrdiff_t n = (ptrdiff_t)(e - t->table); /* CAW: fixed to be 64bit nice, still need the crazy negative case... */
|
|
|
|
/* CAW: this is bad, really bad, maybe stack goes other direction on this machine... */
|
|
if(n < 0) { return -2; }
|
|
|
|
if(t->table[n].k == LH_EMPTY || t->table[n].k == LH_FREED) return -1;
|
|
t->count--;
|
|
if(t->free_fn) t->free_fn(e);
|
|
t->table[n].v = NULL;
|
|
t->table[n].k = LH_FREED;
|
|
if(t->tail == &t->table[n] && t->head == &t->table[n]) {
|
|
t->head = t->tail = NULL;
|
|
} else if (t->head == &t->table[n]) {
|
|
t->head->next->prev = NULL;
|
|
t->head = t->head->next;
|
|
} else if (t->tail == &t->table[n]) {
|
|
t->tail->prev->next = NULL;
|
|
t->tail = t->tail->prev;
|
|
} else {
|
|
t->table[n].prev->next = t->table[n].next;
|
|
t->table[n].next->prev = t->table[n].prev;
|
|
}
|
|
t->table[n].next = t->table[n].prev = NULL;
|
|
return 0;
|
|
}
|
|
|
|
|
|
int lh_table_delete(struct lh_table *t, const void *k)
|
|
{
|
|
struct lh_entry *e = lh_table_lookup_entry(t, k);
|
|
if(!e) return -1;
|
|
return lh_table_delete_entry(t, e);
|
|
}
|
|
|
|
int lh_table_length(struct lh_table *t)
|
|
{
|
|
return t->count;
|
|
}
|