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Diffstat (limited to 'contrib/texinfo/intl/hash-string.h')
-rw-r--r-- | contrib/texinfo/intl/hash-string.h | 63 |
1 files changed, 63 insertions, 0 deletions
diff --git a/contrib/texinfo/intl/hash-string.h b/contrib/texinfo/intl/hash-string.h new file mode 100644 index 0000000..e66e841 --- /dev/null +++ b/contrib/texinfo/intl/hash-string.h @@ -0,0 +1,63 @@ +/* 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. */ + +#ifdef HAVE_VALUES_H +# include <values.h> +#endif + +/* @@ 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; +} |