+/*
+ * ngIRCd -- The Next Generation IRC Daemon
+ * Copyright (c)2001,2002 by Alexander Barton (alex@barton.de)
+ *
+ * Dieses Programm ist freie Software. Sie koennen es unter den Bedingungen
+ * der GNU General Public License (GPL), wie von der Free Software Foundation
+ * herausgegeben, weitergeben und/oder modifizieren, entweder unter Version 2
+ * der Lizenz oder (wenn Sie es wuenschen) jeder spaeteren Version.
+ * Naehere Informationen entnehmen Sie bitter der Datei COPYING. Eine Liste
+ * der an ngIRCd beteiligten Autoren finden Sie in der Datei AUTHORS.
+ *
+ * $Id: hash.c,v 1.1 2002/03/14 15:31:22 alex Exp $
+ *
+ * hash.c: Hash-Werte berechnen
+ */
+
+
+#include "portab.h"
+
+#include "imp.h"
+#include <assert.h>
+
+#include "exp.h"
+#include "hash.h"
+
+
+/*
+ * Die hier verwendete Hash-Funktion stammt aus lookup2.c von Bob Jenkins
+ * (URL: <http://burtleburtle.net/bob/c/lookup2.c>). Aus dem Header:
+ * --------------------------------------------------------------------
+ * lookup2.c, by Bob Jenkins, December 1996, Public Domain.
+ * hash(), hash2(), hash3, and mix() 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 has no warranty.
+ * --------------------------------------------------------------------
+ * nicht alle seiner Funktionen werden hier genutzt.
+ */
+
+
+typedef unsigned long int ub4;
+typedef unsigned char ub1;
+
+
+#define hashsize(n) ((ub4)1<<(n))
+#define hashmask(n) (hashsize(n)-1)
+
+#define mix(a,b,c) \
+{ \
+ a -= b; a -= c; a ^= (c>>13); \
+ b -= c; b -= a; b ^= (a<<8); \
+ c -= a; c -= b; c ^= (b>>13); \
+ a -= b; a -= c; a ^= (c>>12); \
+ b -= c; b -= a; b ^= (a<<16); \
+ c -= a; c -= b; c ^= (b>>5); \
+ a -= b; a -= c; a ^= (c>>3); \
+ b -= c; b -= a; b ^= (a<<10); \
+ c -= a; c -= b; c ^= (b>>15); \
+}
+
+
+ub4 hash( register ub1 *k, register ub4 length, register ub4 initval)
+{
+ /* k: the key
+ * length: length of the key
+ * initval: the previous hash, or an arbitrary value
+ */
+
+ register ub4 a,b,c,len;
+
+ /* Set up the internal state */
+ len = length;
+ a = b = 0x9e3779b9; /* the golden ratio; an arbitrary value */
+ c = initval; /* the previous hash value */
+
+ /* handle most of the key */
+ while (len >= 12)
+ {
+ a += (k[0] +((ub4)k[1]<<8) +((ub4)k[2]<<16) +((ub4)k[3]<<24));
+ b += (k[4] +((ub4)k[5]<<8) +((ub4)k[6]<<16) +((ub4)k[7]<<24));
+ c += (k[8] +((ub4)k[9]<<8) +((ub4)k[10]<<16)+((ub4)k[11]<<24));
+ mix(a,b,c);
+ k += 12; len -= 12;
+ }
+
+ /* handle the last 11 bytes */
+ c += length;
+ switch(len) /* all the case statements fall through */
+ {
+ case 11: c+=((ub4)k[10]<<24);
+ case 10: c+=((ub4)k[9]<<16);
+ case 9 : c+=((ub4)k[8]<<8);
+ /* the first byte of c is reserved for the length */
+ case 8 : b+=((ub4)k[7]<<24);
+ case 7 : b+=((ub4)k[6]<<16);
+ case 6 : b+=((ub4)k[5]<<8);
+ case 5 : b+=k[4];
+ case 4 : a+=((ub4)k[3]<<24);
+ case 3 : a+=((ub4)k[2]<<16);
+ case 2 : a+=((ub4)k[1]<<8);
+ case 1 : a+=k[0];
+ /* case 0: nothing left to add */
+ }
+ mix(a,b,c);
+
+ /* report the result */
+ return c;
+} /* hash */
+
+
+/* -eof- */
projects / ngircd-alex.git / commitdiff