contrib/openbsd_libm/src/s_roundf.c

   1 /*      $OpenBSD: s_roundf.c,v 1.1 2006/07/12 07:26:08 brad Exp $       */
   2
   3 /*-
   4  * Copyright (c) 2003, Steven G. Kargl
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice unmodified, this list of conditions, and the following
  12  *    disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27  */
  28
  29 #include "math.h"
  30 #include "math_private.h"
  31
  32 float
  33 roundf(float x)
  34 {
  35         float t;
  36         uint32_t hx;
  37
  38         GET_FLOAT_WORD(hx, x);
  39         if ((hx & 0x7fffffff) == 0x7f800000)
  40                 return (x + x);
  41
  42         if (!(hx & 0x80000000)) {
  43                 t = floorf(x);
  44                 if (t - x <= -0.5F)
  45                         t += 1;
  46                 return (t);
  47         } else {
  48                 t = floorf(-x);
  49                 if (t + x <= -0.5F)
  50                         t += 1;
  51                 return (-t);
  52         }
  53 }