mingw/share/gettext/intl/hash-string.c

   1 /* Implements a string hashing function.
   2    Copyright (C) 1995, 1997, 1998, 2000, 2003 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, write to the Free
  17    Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  18    Boston, MA 02110-1301, USA.  */
  19
  20 #ifdef HAVE_CONFIG_H
  21 # include <config.h>
  22 #endif
  23
  24 /* Specification.  */
  25 #include "hash-string.h"
  26
  27
  28 /* Defines the so called `hashpjw' function by P.J. Weinberger
  29    [see Aho/Sethi/Ullman, COMPILERS: Principles, Techniques and Tools,
  30    1986, 1987 Bell Telephone Laboratories, Inc.]  */
  31 unsigned long int
  32 __hash_string (const char *str_param)
  33 {
  34   unsigned long int hval, g;
  35   const char *str = str_param;
  36
  37   /* Compute the hash value for the given string.  */
  38   hval = 0;
  39   while (*str != '\0')
  40     {
  41       hval <<= 4;
  42       hval += (unsigned char) *str++;
  43       g = hval & ((unsigned long int) 0xf << (HASHWORDBITS - 4));
  44       if (g != 0)
  45         {
  46           hval ^= g >> (HASHWORDBITS - 8);
  47           hval ^= g;
  48         }
  49     }
  50   return hval;
  51 }