sysdeps/ieee754/flt-32/s_roundf.c

   1 /* Round float to integer away from zero.
   2    Copyright (C) 1997-2019 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <https://www.gnu.org/licenses/>.  */
  19
  20 #define NO_MATH_REDIRECT
  21 #include <math.h>
  22
  23 #include <math_private.h>
  24 #include <libm-alias-float.h>
  25
  26
  27 float
  28 __roundf (float x)
  29 {
  30   int32_t i0, j0;
  31
  32   GET_FLOAT_WORD (i0, x);
  33   j0 = ((i0 >> 23) & 0xff) - 0x7f;
  34   if (j0 < 23)
  35     {
  36       if (j0 < 0)
  37         {
  38           i0 &= 0x80000000;
  39           if (j0 == -1)
  40             i0 |= 0x3f800000;
  41         }
  42       else
  43         {
  44           uint32_t i = 0x007fffff >> j0;
  45           if ((i0 & i) == 0)
  46             /* X is integral.  */
  47             return x;
  48
  49           i0 += 0x00400000 >> j0;
  50           i0 &= ~i;
  51         }
  52     }
  53   else
  54     {
  55       if (j0 == 0x80)
  56         /* Inf or NaN.  */
  57         return x + x;
  58       else
  59         return x;
  60     }
  61
  62   SET_FLOAT_WORD (x, i0);
  63   return x;
  64 }
  65 libm_alias_float (__round, round)