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- /*
- * ngIRCd -- The Next Generation IRC Daemon
- * Copyright (c)2001-2014 Alexander Barton (alex@barton.de) and Contributors.
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- * Please read the file COPYING, README and AUTHORS for more information.
- */
- #include "portab.h"
- /**
- * @file
- * Hash calculation
- */
- #include <assert.h>
- #include <string.h>
- #include "defines.h"
- #include "tool.h"
- #include "hash.h"
- static UINT32 jenkins_hash PARAMS((UINT8 *k, UINT32 length, UINT32 initval));
- /**
- * Calculate hash value for a given string.
- *
- * @param String Input string
- * @return 32 bit hash value
- */
- GLOBAL UINT32
- Hash( const char *String )
- {
- char buffer[COMMAND_LEN];
- strlcpy(buffer, String, sizeof(buffer));
- return jenkins_hash((UINT8 *)ngt_LowerStr(buffer),
- (UINT32)strlen(buffer), 42);
- } /* Hash */
- /*
- * This hash function originates from lookup3.c of Bob Jenkins
- * (URL: <http://burtleburtle.net/bob/c/lookup3.c>):
- * --------------------------------------------------------------------
- * 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.
- * --------------------------------------------------------------------
- * Not all of his functions are used here.
- */
- #define hashsize(n) ((UINT32)1<<(n))
- #define hashmask(n) (hashsize(n)-1)
- #define rot(x,k) (((x)<<(k)) | ((x)>>(32-(k))))
- #define 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; \
- } /* mix */
- #define 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); \
- }
- static UINT32
- jenkins_hash(UINT8 *k, UINT32 length, UINT32 initval)
- {
- /* k: the key
- * length: length of the key
- * initval: the previous hash, or an arbitrary value
- */
- UINT32 a,b,c;
- /* Set up the internal state */
- a = b = c = 0xdeadbeef + length + initval;
- /* handle most of the key */
- while (length > 12) {
- a += (k[0] +((UINT32)k[1]<<8) +((UINT32)k[2]<<16) +((UINT32)k[3]<<24));
- b += (k[4] +((UINT32)k[5]<<8) +((UINT32)k[6]<<16) +((UINT32)k[7]<<24));
- c += (k[8] +((UINT32)k[9]<<8) +((UINT32)k[10]<<16)+((UINT32)k[11]<<24));
- mix(a,b,c);
- length -= 12;
- k += 12;
- }
- /*-------------------------------- last block: affect all 32 bits of (c) */
- switch(length) /* all the case statements fall through */
- {
- case 12: c+=((UINT32)k[11])<<24;
- case 11: c+=((UINT32)k[10]<<16);
- case 10: c+=((UINT32)k[9]<<8);
- case 9 : c+=k[8];
- case 8 : b+=((UINT32)k[7]<<24);
- case 7 : b+=((UINT32)k[6]<<16);
- case 6 : b+=((UINT32)k[5]<<8);
- case 5 : b+=k[4];
- case 4 : a+=((UINT32)k[3]<<24);
- case 3 : a+=((UINT32)k[2]<<16);
- case 2 : a+=((UINT32)k[1]<<8);
- case 1 : a+=k[0];
- break;
- case 0 : return c;
- }
- final(a,b,c);
- return c;
- } /* jenkins_hash */
- /* -eof- */
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