usr/src/lib/libast/common/string/strsearch.c

   1 /***********************************************************************
   2 *                                                                      *
   3 *               This software is part of the ast package               *
   4 *          Copyright (c) 1985-2010 AT&T Intellectual Property          *
   5 *                      and is licensed under the                       *
   6 *                  Common Public License, Version 1.0                  *
   7 *                    by AT&T Intellectual Property                     *
   8 *                                                                      *
   9 *                A copy of the License is available at                 *
  10 *            http://www.opensource.org/licenses/cpl1.0.txt             *
  11 *         (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9)         *
  12 *                                                                      *
  13 *              Information and Software Systems Research               *
  14 *                            AT&T Research                             *
  15 *                           Florham Park NJ                            *
  16 *                                                                      *
  17 *                 Glenn Fowler <gsf@research.att.com>                  *
  18 *                  David Korn <dgk@research.att.com>                   *
  19 *                   Phong Vo <kpv@research.att.com>                    *
  20 *                                                                      *
  21 ***********************************************************************/
  22 #pragma prototyped
  23 /*
  24  * Glenn Fowler
  25  * AT&T Research
  26  */
  27
  28 #include <ast.h>
  29
  30 /*
  31  * return a pointer to the element matching
  32  * name in the (*comparf*)() sorted tab of num elements of
  33  * size siz where the first member of each
  34  * element is a char*
  35  *
  36  * 0 returned if name not found
  37  */
  38
  39 void*
  40 strsearch(const void* tab, size_t num, size_t siz, Strcmp_f comparf, const char* name, void* context)
  41 {
  42         register char*          lo = (char*)tab;
  43         register char*          hi = lo + (num - 1) * siz;
  44         register char*          mid;
  45         register int            v;
  46
  47         while (lo <= hi)
  48         {
  49                 mid = lo + (((hi - lo) / siz) / 2) * siz;
  50                 if (!(v = context ? (*(Strcmp_context_f)comparf)(name, *((char**)mid), context) : (*comparf)(name, *((char**)mid))))
  51                         return (void*)mid;
  52                 else if (v > 0)
  53                         lo = mid + siz;
  54                 else hi = mid - siz;
  55         }
  56         return 0;
  57 }