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authorElliot Lee <sopwith@src.gnome.org>1997-11-24 22:32:04 +0000
committerElliot Lee <sopwith@src.gnome.org>1997-11-24 22:32:04 +0000
commit260b95407d215f8ef2bfd90bfdf44e97dc0010ae (patch)
tree23f04282ba39208dbf92dda5e4fb6d0f8c33f66f /intl/hash-string.h
parent2928c4e707104b312d1ab3e75e24c57e680313ce (diff)
downloadshared-mime-info-260b95407d215f8ef2bfd90bfdf44e97dc0010ae.tar.gz
Initial revision
svn path=/trunk/; revision=50
Diffstat (limited to 'intl/hash-string.h')
-rw-r--r--intl/hash-string.h62
1 files changed, 62 insertions, 0 deletions
diff --git a/intl/hash-string.h b/intl/hash-string.h
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+++ b/intl/hash-string.h
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+/* hash-string - Implements a string hashing function.
+ Copyright (C) 1995 Free Software Foundation, Inc.
+
+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, or (at your option)
+any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program; if not, write to the Free Software
+Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
+
+#ifdef HAVE_VALUES_H
+# include <values.h>
+#endif
+
+/* @@ end of prolog @@ */
+
+#ifndef __P
+# if __STDC__
+# define __P(Args) Args
+# else
+# define __P(Args) ()
+# endif
+#endif
+
+/* We assume to have `unsigned long int' value with at least 32 bits. */
+#define HASHWORDBITS 32
+
+
+/* Defines the so called `hashpjw' function by P.J. Weinberger
+ [see Aho/Sethi/Ullman, COMPILERS: Principles, Techniques and Tools,
+ 1986, 1987 Bell Telephone Laboratories, Inc.] */
+static unsigned long hash_string __P ((const char *__str_param));
+
+static inline unsigned long
+hash_string (str_param)
+ const char *str_param;
+{
+ unsigned long int hval, g;
+ const char *str = str_param;
+
+ /* Compute the hash value for the given string. */
+ hval = 0;
+ while (*str != '\0')
+ {
+ hval <<= 4;
+ hval += (unsigned long) *str++;
+ g = hval & ((unsigned long) 0xf << (HASHWORDBITS - 4));
+ if (g != 0)
+ {
+ hval ^= g >> (HASHWORDBITS - 8);
+ hval ^= g;
+ }
+ }
+ return hval;
+}