usr/src/cmd/sgs/tools/common/findprime.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License, Version 1.0 only
   6  * (the "License").  You may not use this file except in compliance
   7  * with the License.
   8  *
   9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
  10  * or http://www.opensolaris.org/os/licensing.
  11  * See the License for the specific language governing permissions
  12  * and limitations under the License.
  13  *
  14  * When distributing Covered Code, include this CDDL HEADER in each
  15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  16  * If applicable, add the following below this CDDL HEADER, with the
  17  * fields enclosed by brackets "[]" replaced with your own identifying
  18  * information: Portions Copyright [yyyy] [name of copyright owner]
  19  *
  20  * CDDL HEADER END
  21  */
  22 /*
  23  * Copyright 2003 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 #pragma ident   "%Z%%M% %I%     %E% SMI"
  28
  29 #include <sys/types.h>
  30
  31 /*
  32  * function that will find a prime'ish number.  Usefull for
  33  * hashbuckets and related things.
  34  */
  35 uint_t
  36 findprime(uint_t count)
  37 {
  38         uint_t  h, f;
  39
  40         if (count <= 3)
  41                 return (3);
  42
  43
  44         /*
  45          * Check to see if divisible by two, if so
  46          * increment.
  47          */
  48         if ((count & 0x1) == 0)
  49                 count++;
  50
  51         for (h = count, f = 2; f * f <= h; f++)
  52                 if ((h % f) == 0)
  53                         h += f = 1;
  54         return (h);
  55 }