src/hash.c

   1 /* hash.c */
   2 /* String hashing function */
   3 /* Copyright (C) 1995-2002 Olly Betts
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program 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
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  18  */
  19
  20 #include <config.h>
  21
  22 #include <ctype.h>
  23
  24 #include "debug.h"
  25 #include "hash.h"
  26
  27 /* some (preferably prime) number for the hashing function */
  28 #define HASH_PRIME 29363
  29
  30 #ifdef __clang__
  31 __attribute__((no_sanitize("unsigned-integer-overflow")))
  32 #endif
  33 int
  34 hash_string(const char *p)
  35 {
  36    int hash;
  37    SVX_ASSERT(p);
  38    for (hash = 0; *p; p++)
  39       hash = (hash * HASH_PRIME + *(const unsigned char*)p) & 0x7fff;
  40    return hash;
  41 }
  42
  43 #ifdef __clang__
  44 __attribute__((no_sanitize("unsigned-integer-overflow")))
  45 #endif
  46 int
  47 hash_lc_string(const char *p)
  48 {
  49    int hash;
  50    SVX_ASSERT(p);
  51    for (hash = 0; *p; p++)
  52       hash = (hash * HASH_PRIME + tolower(*(const unsigned char*)p)) & 0x7fff;
  53    return hash;
  54 }
  55
  56 #ifdef __clang__
  57 __attribute__((no_sanitize("unsigned-integer-overflow")))
  58 #endif
  59 int
  60 hash_data(const char *p, size_t len)
  61 {
  62    int hash;
  63    SVX_ASSERT(p);
  64    for (hash = 0; len--; p++)
  65       hash = (hash * HASH_PRIME + *(const unsigned char*)p) & 0x7fff;
  66    return hash;
  67 }