sysdeps/ieee754/ldbl-128/s_lroundl.c

   1 /* Round long double value to long int.
   2    Copyright (C) 1997-2016 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997 and
   5                   Jakub Jelinek <jj@ultra.linux.cz>, 1999.
   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 long int
  29 __lroundl (_Float128 x)
  30 {
  31   int64_t j0;
  32   u_int64_t i1, i0;
  33   long int result;
  34   int sign;
  35
  36   GET_LDOUBLE_WORDS64 (i0, i1, x);
  37   j0 = ((i0 >> 48) & 0x7fff) - 0x3fff;
  38   sign = (i0 & 0x8000000000000000ULL) != 0 ? -1 : 1;
  39   i0 &= 0x0000ffffffffffffLL;
  40   i0 |= 0x0001000000000000LL;
  41
  42   if (j0 < (int32_t) (8 * sizeof (long int)) - 1)
  43     {
  44       if (j0 < 48)
  45         {
  46           if (j0 < 0)
  47             return j0 < -1 ? 0 : sign;
  48           else
  49             {
  50               i0 += 0x0000800000000000LL >> j0;
  51               result = i0 >> (48 - j0);
  52 #ifdef FE_INVALID
  53               if (sizeof (long int) == 4
  54                   && sign == 1
  55                   && result == LONG_MIN)
  56                 /* Rounding brought the value out of range.  */
  57                 feraiseexcept (FE_INVALID);
  58 #endif
  59             }
  60         }
  61       else if (j0 >= 112)
  62         result = ((long int) i0 << (j0 - 48)) | (i1 << (j0 - 112));
  63       else
  64         {
  65           u_int64_t j = i1 + (0x8000000000000000ULL >> (j0 - 48));
  66           if (j < i1)
  67             ++i0;
  68
  69           if (j0 == 48)
  70             result = (long int) i0;
  71           else
  72             {
  73               result = ((long int) i0 << (j0 - 48)) | (j >> (112 - j0));
  74 #ifdef FE_INVALID
  75               if (sizeof (long int) == 8
  76                   && sign == 1
  77                   && result == LONG_MIN)
  78                 /* Rounding brought the value out of range.  */
  79                 feraiseexcept (FE_INVALID);
  80 #endif
  81             }
  82         }
  83     }
  84   else
  85     {
  86       /* The number is too large.  Unless it rounds to LONG_MIN,
  87          FE_INVALID must be raised and the return value is
  88          unspecified.  */
  89 #ifdef FE_INVALID
  90       if (FIX_LDBL_LONG_CONVERT_OVERFLOW
  91           && !(sign == -1 && x > (_Float128) LONG_MIN - L(0.5)))
  92         {
  93           feraiseexcept (FE_INVALID);
  94           return sign == 1 ? LONG_MAX : LONG_MIN;
  95         }
  96       else if (!FIX_LDBL_LONG_CONVERT_OVERFLOW
  97                && x <= (_Float128) LONG_MIN - L(0.5))
  98         {
  99           /* If truncation produces LONG_MIN, the cast will not raise
 100              the exception, but may raise "inexact".  */
 101           feraiseexcept (FE_INVALID);
 102           return LONG_MIN;
 103         }
 104 #endif
 105       /* The number is too large.  It is left implementation defined
 106          what happens.  */
 107       return (long int) x;
 108     }
 109
 110   return sign * result;
 111 }
 112
 113 weak_alias (__lroundl, lroundl)