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Annotation of embedaddon/lrzsz/intl/hash-string.h, revision 1.1

1.1     ! misho       1: /* Implements a string hashing function.
        !             2:    Copyright (C) 1995, 1997 Free Software Foundation, Inc.
        !             3: 
        !             4:    This program is free software; you can redistribute it and/or modify
        !             5:    it under the terms of the GNU General Public License as published by
        !             6:    the Free Software Foundation; either version 2, or (at your option)
        !             7:    any later version.
        !             8: 
        !             9:    This program is distributed in the hope that it will be useful,
        !            10:    but WITHOUT ANY WARRANTY; without even the implied warranty of
        !            11:    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
        !            12:    GNU General Public License for more details.
        !            13: 
        !            14:    You should have received a copy of the GNU Library General Public
        !            15:    License along with the GNU C Library; see the file COPYING.LIB.  If not,
        !            16:    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
        !            17:    Boston, MA 02111-1307, USA.  */
        !            18: 
        !            19: #ifdef HAVE_VALUES_H
        !            20: # include <values.h>
        !            21: #endif
        !            22: 
        !            23: /* @@ end of prolog @@ */
        !            24: 
        !            25: #ifndef PARAMS
        !            26: # if __STDC__
        !            27: #  define PARAMS(Args) Args
        !            28: # else
        !            29: #  define PARAMS(Args) ()
        !            30: # endif
        !            31: #endif
        !            32: 
        !            33: /* We assume to have `unsigned long int' value with at least 32 bits.  */
        !            34: #define HASHWORDBITS 32
        !            35: 
        !            36: 
        !            37: /* Defines the so called `hashpjw' function by P.J. Weinberger
        !            38:    [see Aho/Sethi/Ullman, COMPILERS: Principles, Techniques and Tools,
        !            39:    1986, 1987 Bell Telephone Laboratories, Inc.]  */
        !            40: static unsigned long hash_string PARAMS ((const char *__str_param));
        !            41: 
        !            42: static inline unsigned long
        !            43: hash_string (str_param)
        !            44:      const char *str_param;
        !            45: {
        !            46:   unsigned long int hval, g;
        !            47:   const char *str = str_param;
        !            48: 
        !            49:   /* Compute the hash value for the given string.  */
        !            50:   hval = 0;
        !            51:   while (*str != '\0')
        !            52:     {
        !            53:       hval <<= 4;
        !            54:       hval += (unsigned long) *str++;
        !            55:       g = hval & ((unsigned long) 0xf << (HASHWORDBITS - 4));
        !            56:       if (g != 0)
        !            57:        {
        !            58:          hval ^= g >> (HASHWORDBITS - 8);
        !            59:          hval ^= g;
        !            60:        }
        !            61:     }
        !            62:   return hval;
        !            63: }