Initial revision

From-SVN: r19482

gcc/intl/hash-string.h

+/* Implements a string hashing function.
+   Copyright (C) 1995, 1997 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 Library General Public
+   License along with the GNU C Library; see the file COPYING.LIB.  If not,
+   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+   Boston, MA 02111-1307, USA.  */
+
+/* @@ end of prolog @@ */
+
+#ifndef PARAMS
+# if __STDC__
+#  define PARAMS(Args) Args
+# else
+#  define PARAMS(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 PARAMS ((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;
+}