mono/utils/bsearch.c

   1 /*
   2  * bsearch () implementation. Needed because some broken platforms
   3  * have implementations that have unreasonable, non-standard
   4  * requirements (e.g. "key must not be null"). Taken from NetBSD
   5  * with some minor modifications.
   6  *
   7  * Copyright (c) 1990, 1993
   8  *      The Regents of the University of California.  All rights reserved.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. Neither the name of the University nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  */
  34
  35 #include "mono/utils/bsearch.h"
  36
  37 void *
  38 mono_binary_search (
  39         const void *key,
  40         const void *array,
  41         size_t array_length,
  42         size_t member_size,
  43         BinarySearchComparer comparer)
  44 {
  45         const char *base = (const char *)array;
  46         size_t lim;
  47         int cmp;
  48         const void *p;
  49
  50         for (lim = array_length; lim; lim >>= 1) {
  51                 p = base + (lim >> 1) * member_size;
  52                 cmp = (* comparer) (key, p);
  53
  54                 if (!cmp)
  55                         return (void *) p;
  56                 else if (cmp > 0) {
  57                         base = (const char *) p + member_size;
  58                         lim--;
  59                 }
  60         }
  61
  62         return NULL;
  63 }