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 1.3 2013/11/11 23:57:34 joerg 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 #ifndef __HAVE_LONG_DOUBLE
  38 __strong_alias(_roundl, round)
  39 __weak_alias(roundl, round)
  40 #endif
  41
  42 double
  43 round(double x)
  44 {
  45         double t;
  46         int i;
  47
  48         i = fpclassify(x);
  49         if (i == FP_INFINITE || i == FP_NAN)
  50                 return (x);
  51
  52         if (x >= 0.0) {
  53                 t = floor(x);
  54                 if (x - t >= 0.5)
  55                         t += 1.0;
  56                 return (t);
  57         } else {
  58                 x = -x;
  59                 t = floor(x);
  60                 if (x - t >= 0.5)
  61                         t += 1.0;
  62                 return (-t);
  63         }
  64 }