lib/libm/src/s_roundf.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  * $FreeBSD: src/lib/msun/src/s_roundf.c,v 1.1 2004/06/07 08:05:36 das Exp $
  27  * $NetBSD: s_roundf.c,v 1.1 2004/07/10 13:49:10 junyoung Exp $
  28  * $DragonFly: src/lib/libm/src/s_roundf.c,v 1.1 2005/07/26 21:15:20 joerg Exp $
  29  */
  30
  31 #include <math.h>
  32
  33 float
  34 roundf(float x)
  35 {
  36         float t;
  37         int i;
  38
  39         i = fpclassify(x);
  40         if (i == FP_INFINITE || i == FP_NAN)
  41                 return (x);
  42
  43         if (x >= 0.0) {
  44                 t = ceilf(x);
  45                 if (t - x > 0.5)
  46                         t -= 1.0;
  47                 return (t);
  48         } else {
  49                 t = ceilf(-x);
  50                 if (t + x > 0.5)
  51                         t -= 1.0;
  52                 return (-t);
  53         }
  54 }