126 lines
3.3 KiB
C
126 lines
3.3 KiB
C
/*
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* ngIRCd -- The Next Generation IRC Daemon
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* Copyright (c)2001,2002 by Alexander Barton (alex@barton.de)
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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* Please read the file COPYING, README and AUTHORS for more information.
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*
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* Hash calculation
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*/
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#include "portab.h"
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static char UNUSED id[] = "$Id: hash.c,v 1.13 2006/10/06 21:23:47 fw Exp $";
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#include "imp.h"
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#include <assert.h>
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#include <string.h>
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#include "defines.h"
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#include "tool.h"
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#include "exp.h"
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#include "hash.h"
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static UINT32 jenkins_hash PARAMS(( register UINT8 *k, register UINT32 length, register UINT32 initval ));
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GLOBAL UINT32
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Hash( const char *String )
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{
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/* Hash-Wert ueber String berechnen */
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char buffer[LINE_LEN];
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strlcpy( buffer, String, sizeof( buffer ));
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return jenkins_hash( (UINT8 *)ngt_LowerStr( buffer ), strlen( buffer ), 42 );
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} /* Hash */
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/*
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* Die hier verwendete Hash-Funktion stammt aus lookup2.c von Bob Jenkins
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* (URL: <http://burtleburtle.net/bob/c/lookup2.c>). Aus dem Header:
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* --------------------------------------------------------------------
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* lookup2.c, by Bob Jenkins, December 1996, Public Domain.
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* hash(), hash2(), hash3, and mix() are externally useful functions.
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* Routines to test the hash are included if SELF_TEST is defined.
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* You can use this free for any purpose. It has no warranty.
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* --------------------------------------------------------------------
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* nicht alle seiner Funktionen werden hier genutzt.
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*/
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#define hashsize(n) ((UINT32)1<<(n))
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#define hashmask(n) (hashsize(n)-1)
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#define mix(a,b,c) \
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{ \
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a -= b; a -= c; a ^= (c>>13); \
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b -= c; b -= a; b ^= (a<<8); \
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c -= a; c -= b; c ^= (b>>13); \
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a -= b; a -= c; a ^= (c>>12); \
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b -= c; b -= a; b ^= (a<<16); \
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c -= a; c -= b; c ^= (b>>5); \
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a -= b; a -= c; a ^= (c>>3); \
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b -= c; b -= a; b ^= (a<<10); \
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c -= a; c -= b; c ^= (b>>15); \
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} /* mix */
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static UINT32
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jenkins_hash( register UINT8 *k, register UINT32 length, register UINT32 initval )
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{
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/* k: the key
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* length: length of the key
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* initval: the previous hash, or an arbitrary value
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*/
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register UINT32 a,b,c,len;
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/* Set up the internal state */
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len = length;
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a = b = 0x9e3779b9; /* the golden ratio; an arbitrary value */
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c = initval; /* the previous hash value */
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/* handle most of the key */
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while (len >= 12)
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{
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a += (k[0] +((UINT32)k[1]<<8) +((UINT32)k[2]<<16) +((UINT32)k[3]<<24));
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b += (k[4] +((UINT32)k[5]<<8) +((UINT32)k[6]<<16) +((UINT32)k[7]<<24));
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c += (k[8] +((UINT32)k[9]<<8) +((UINT32)k[10]<<16)+((UINT32)k[11]<<24));
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mix(a,b,c);
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k += 12; len -= 12;
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}
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/* handle the last 11 bytes */
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c += length;
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switch( (int)len ) /* all the case statements fall through */
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{
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case 11: c+=((UINT32)k[10]<<24);
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case 10: c+=((UINT32)k[9]<<16);
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case 9 : c+=((UINT32)k[8]<<8);
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/* the first byte of c is reserved for the length */
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case 8 : b+=((UINT32)k[7]<<24);
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case 7 : b+=((UINT32)k[6]<<16);
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case 6 : b+=((UINT32)k[5]<<8);
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case 5 : b+=k[4];
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case 4 : a+=((UINT32)k[3]<<24);
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case 3 : a+=((UINT32)k[2]<<16);
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case 2 : a+=((UINT32)k[1]<<8);
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case 1 : a+=k[0];
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/* case 0: nothing left to add */
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}
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mix(a,b,c);
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/* report the result */
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return c;
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} /* jenkins_hash */
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/* -eof- */
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