lib/libm/src/s_round.c

   1 /*-
   2  * Copyright (c) 2003, Steven G. Kargl
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice unmodified, this list of conditions, and the following
  10  *    disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  25  */
  26
  27 #include <sys/cdefs.h>
  28 #if defined(LIBM_SCCS) && !defined(lint)
  29 __RCSID("$NetBSD: s_round.c,v 1.2 2007/08/21 20:10:27 drochner Exp $");
  30 #if 0
  31 __FBSDID("$FreeBSD: src/lib/msun/src/s_round.c,v 1.1 2004/06/07 08:05:36 das Exp $");
  32 #endif
  33 #endif
  34
  35 #include <math.h>
  36
  37 double
  38 round(double x)
  39 {
  40         double t;
  41         int i;
  42
  43         i = fpclassify(x);
  44         if (i == FP_INFINITE || i == FP_NAN)
  45                 return (x);
  46
  47         if (x >= 0.0) {
  48                 t = floor(x);
  49                 if (x - t >= 0.5)
  50                         t += 1.0;
  51                 return (t);
  52         } else {
  53                 x = -x;
  54                 t = floor(x);
  55                 if (x - t >= 0.5)
  56                         t += 1.0;
  57                 return (-t);
  58         }
  59 }