sysdeps/ieee754/ldbl-96/s_llroundl.c

   1 /* Round long double value to long long int.
   2    Copyright (C) 1997-2018 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    <http://www.gnu.org/licenses/>.  */
  19
  20 #include <fenv.h>
  21 #include <limits.h>
  22 #include <math.h>
  23
  24 #include <math_private.h>
  25 #include <libm-alias-ldouble.h>
  26
  27
  28 long long int
  29 __llroundl (long double x)
  30 {
  31   int32_t j0;
  32   uint32_t se, i1, i0;
  33   long long int result;
  34   int sign;
  35
  36   GET_LDOUBLE_WORDS (se, i0, i1, x);
  37   j0 = (se & 0x7fff) - 0x3fff;
  38   sign = (se & 0x8000) != 0 ? -1 : 1;
  39
  40   if (j0 < 31)
  41     {
  42       if (j0 < 0)
  43         return j0 < -1 ? 0 : sign;
  44       else
  45         {
  46           uint32_t j = i0 + (0x40000000 >> j0);
  47           if (j < i0)
  48             {
  49               j >>= 1;
  50               j |= 0x80000000;
  51               ++j0;
  52             }
  53
  54           result = j >> (31 - j0);
  55         }
  56     }
  57   else if (j0 < (int32_t) (8 * sizeof (long long int)) - 1)
  58     {
  59       if (j0 >= 63)
  60         result = (((long long int) i0 << 32) | i1) << (j0 - 63);
  61       else
  62         {
  63           uint32_t j = i1 + (0x80000000 >> (j0 - 31));
  64
  65           result = (long long int) i0;
  66           if (j < i1)
  67             ++result;
  68
  69           if (j0 > 31)
  70             {
  71               result = (result << (j0 - 31)) | (j >> (63 - j0));
  72 #ifdef FE_INVALID
  73               if (sign == 1 && result == LLONG_MIN)
  74                 /* Rounding brought the value out of range.  */
  75                 feraiseexcept (FE_INVALID);
  76 #endif
  77             }
  78         }
  79     }
  80   else
  81     {
  82       /* The number is too large.  It is left implementation defined
  83          what happens.  */
  84       return (long long int) x;
  85     }
  86
  87   return sign * result;
  88 }
  89
  90 libm_alias_ldouble (__llround, llround)