sysdeps/ieee754/flt-32/s_llrintf.c

   1 /* Round argument to nearest integral value according to current rounding
   2    direction.
   3    Copyright (C) 1997-2016 Free Software Foundation, Inc.
   4    This file is part of the GNU C Library.
   5    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
   6
   7    The GNU C Library is free software; you can redistribute it and/or
   8    modify it under the terms of the GNU Lesser General Public
   9    License as published by the Free Software Foundation; either
  10    version 2.1 of the License, or (at your option) any later version.
  11
  12    The GNU C Library is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15    Lesser General Public License for more details.
  16
  17    You should have received a copy of the GNU Lesser General Public
  18    License along with the GNU C Library; if not, see
  19    <http://www.gnu.org/licenses/>.  */
  20
  21 #include <fenv.h>
  22 #include <limits.h>
  23 #include <math.h>
  24
  25 #include <math_private.h>
  26 #include <fix-fp-int-convert-overflow.h>
  27
  28 static const float two23[2] =
  29 {
  30   8.3886080000e+06, /* 0x4B000000 */
  31  -8.3886080000e+06, /* 0xCB000000 */
  32 };
  33
  34
  35 long long int
  36 __llrintf (float x)
  37 {
  38   int32_t j0;
  39   u_int32_t i0;
  40   float w;
  41   float t;
  42   long long int result;
  43   int sx;
  44
  45   GET_FLOAT_WORD (i0, x);
  46
  47   sx = i0 >> 31;
  48   j0 = ((i0 >> 23) & 0xff) - 0x7f;
  49   i0 &= 0x7fffff;
  50   i0 |= 0x800000;
  51
  52   if (j0 < (int32_t) (sizeof (long long int) * 8) - 1)
  53     {
  54       if (j0 >= 23)
  55         result = (long long int) i0 << (j0 - 23);
  56       else
  57         {
  58           w = math_narrow_eval (two23[sx] + x);
  59           t = w - two23[sx];
  60           GET_FLOAT_WORD (i0, t);
  61           j0 = ((i0 >> 23) & 0xff) - 0x7f;
  62           i0 &= 0x7fffff;
  63           i0 |= 0x800000;
  64
  65           result = (j0 < 0 ? 0 : i0 >> (23 - j0));
  66         }
  67     }
  68   else
  69     {
  70 #ifdef FE_INVALID
  71       /* The number is too large.  Unless it rounds to LLONG_MIN,
  72          FE_INVALID must be raised and the return value is
  73          unspecified.  */
  74       if (FIX_FLT_LLONG_CONVERT_OVERFLOW && x != (float) LLONG_MIN)
  75         {
  76           feraiseexcept (FE_INVALID);
  77           return sx == 0 ? LLONG_MAX : LLONG_MIN;
  78         }
  79 #endif
  80       return (long long int) x;
  81     }
  82
  83   return sx ? -result : result;
  84 }
  85
  86 weak_alias (__llrintf, llrintf)