sysdeps/ieee754/ldbl-96/s_llrintl.c

   1 /* Round argument to nearest integral value according to current rounding
   2    direction.
   3    Copyright (C) 1997-2018 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 <libm-alias-ldouble.h>
  27
  28 static const long double two63[2] =
  29 {
  30   9.223372036854775808000000e+18, /* 0x403E, 0x00000000, 0x00000000 */
  31  -9.223372036854775808000000e+18  /* 0xC03E, 0x00000000, 0x00000000 */
  32 };
  33
  34
  35 long long int
  36 __llrintl (long double x)
  37 {
  38   int32_t se,j0;
  39   uint32_t i0, i1;
  40   long long int result;
  41   long double w;
  42   long double t;
  43   int sx;
  44
  45   GET_LDOUBLE_WORDS (se, i0, i1, x);
  46
  47   sx = (se >> 15) & 1;
  48   j0 = (se & 0x7fff) - 0x3fff;
  49
  50   if (j0 < (int32_t) (8 * sizeof (long long int)) - 1)
  51     {
  52       if (j0 >= 63)
  53         result = (((long long int) i0 << 32) | i1) << (j0 - 63);
  54       else
  55         {
  56 #if defined FE_INVALID || defined FE_INEXACT
  57           /* X < LLONG_MAX + 1 implied by J0 < 63.  */
  58           if (x > (long double) LLONG_MAX)
  59             {
  60               /* In the event of overflow we must raise the "invalid"
  61                  exception, but not "inexact".  */
  62               t = __nearbyintl (x);
  63               feraiseexcept (t == LLONG_MAX ? FE_INEXACT : FE_INVALID);
  64             }
  65           else
  66 #endif
  67             {
  68               w = two63[sx] + x;
  69               t = w - two63[sx];
  70             }
  71           GET_LDOUBLE_WORDS (se, i0, i1, t);
  72           j0 = (se & 0x7fff) - 0x3fff;
  73
  74           if (j0 < 0)
  75             result = 0;
  76           else if (j0 <= 31)
  77             result = i0 >> (31 - j0);
  78           else
  79             result = ((long long int) i0 << (j0 - 31)) | (i1 >> (63 - j0));
  80         }
  81     }
  82   else
  83     {
  84       /* The number is too large.  It is left implementation defined
  85          what happens.  */
  86       return (long long int) x;
  87     }
  88
  89   return sx ? -result : result;
  90 }
  91
  92 libm_alias_ldouble (__llrint, llrint)