mono/utils/bsearch.c

   1 /**
   2  * \file
   3  * bsearch () implementation. Needed because some broken platforms
   4  * have implementations that have unreasonable, non-standard
   5  * requirements (e.g. "key must not be null"). Taken from NetBSD
   6  * with some minor modifications.
   7  *
   8  * Copyright (c) 1990, 1993
   9  *      The Regents of the University of California.  All rights reserved.
  10  *
  11  * Redistribution and use in source and binary forms, with or without
  12  * modification, are permitted provided that the following conditions
  13  * are met:
  14  * 1. Redistributions of source code must retain the above copyright
  15  *    notice, this list of conditions and the following disclaimer.
  16  * 2. Redistributions in binary form must reproduce the above copyright
  17  *    notice, this list of conditions and the following disclaimer in the
  18  *    documentation and/or other materials provided with the distribution.
  19  * 3. Neither the name of the University nor the names of its contributors
  20  *    may be used to endorse or promote products derived from this software
  21  *    without specific prior written permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  33  * SUCH DAMAGE.
  34  */
  35
  36 #include "mono/utils/bsearch.h"
  37
  38 void *
  39 mono_binary_search (
  40         const void *key,
  41         const void *array,
  42         size_t array_length,
  43         size_t member_size,
  44         BinarySearchComparer comparer)
  45 {
  46         const char *base = (const char *)array;
  47         size_t lim;
  48         int cmp;
  49         const void *p;
  50
  51         for (lim = array_length; lim; lim >>= 1) {
  52                 p = base + (lim >> 1) * member_size;
  53                 cmp = (* comparer) (key, p);
  54
  55                 if (!cmp)
  56                         return (void *) p;
  57                 else if (cmp > 0) {
  58                         base = (const char *) p + member_size;
  59                         lim--;
  60                 }
  61         }
  62
  63         return NULL;
  64 }