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Diffstat (limited to 'intl/hash-string.h')
-rw-r--r-- | intl/hash-string.h | 56 |
1 files changed, 56 insertions, 0 deletions
diff --git a/intl/hash-string.h b/intl/hash-string.h new file mode 100644 index 0000000000..e846b507ac --- /dev/null +++ b/intl/hash-string.h @@ -0,0 +1,56 @@ +/* hash-string - Implements a string hashing function. + Copyright (C) 1995 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 BITSPERBYTE +# define BITSPERBYTE 8 +#endif + +#ifndef LONGBITS +# define LONGBITS (sizeof (long) * BITSPERBYTE) +#endif /* LONGBITS */ + +/* 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 inline unsigned long +hash_string (str_param) + const char *str_param; +{ + unsigned long 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 << (LONGBITS - 4)); + if (g != 0) + { + hval ^= g >> (LONGBITS - 8); + hval ^= g; + } + } + return hval; +} |