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Diffstat (limited to 'locale/strlen-hash.h')
-rw-r--r-- | locale/strlen-hash.h | 51 |
1 files changed, 51 insertions, 0 deletions
diff --git a/locale/strlen-hash.h b/locale/strlen-hash.h new file mode 100644 index 0000000000..dba56dff21 --- /dev/null +++ b/locale/strlen-hash.h @@ -0,0 +1,51 @@ +/* strlen-hash - Implements hashing function for string with known length. +Copyright (C) 1996 Free Software Foundation, Inc. +Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996. + +The GNU C Library is free software; you can redistribute it and/or +modify it under the terms of the GNU Library General Public License as +published by the Free Software Foundation; either version 2 of the +License, or (at your option) any later version. + +The GNU C Library 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 +Library 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. */ + +#include <sys/types.h> + +/* We assume to have `size_t' 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 size_t hash_string (const char *__str_param, size_t __len); + +static inline size_t +hash_string (const char *str_param, size_t len) +{ + size_t hval, g; + const char *end_str = str_param + len; + + /* Compute the hash value for the given string. */ + hval = len; + while (str_param != end_str) + { + hval <<= 4; + hval += (size_t) *str_param++; + g = hval & ((size_t) 0xf << (HASHWORDBITS - 4)); + if (g != 0) + { + hval ^= g >> (HASHWORDBITS - 8); + hval ^= g; + } + } + return hval; +} |