sysdeps/ieee754/ldbl-128/s_lrintl.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 and
   6                   Jakub Jelinek <jj@ultra.linux.cz>, 1999.
   7
   8    The GNU C Library is free software; you can redistribute it and/or
   9    modify it under the terms of the GNU Lesser General Public
  10    License as published by the Free Software Foundation; either
  11    version 2.1 of the License, or (at your option) any later version.
  12
  13    The GNU C Library is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16    Lesser General Public License for more details.
  17
  18    You should have received a copy of the GNU Lesser General Public
  19    License along with the GNU C Library; if not, see
  20    <http://www.gnu.org/licenses/>.  */
  21
  22 #include <fenv.h>
  23 #include <limits.h>
  24 #include <math.h>
  25
  26 #include <math_private.h>
  27 #include <fix-fp-int-convert-overflow.h>
  28
  29 static const long double two112[2] =
  30 {
  31   5.19229685853482762853049632922009600E+33L, /* 0x406F000000000000, 0 */
  32  -5.19229685853482762853049632922009600E+33L  /* 0xC06F000000000000, 0 */
  33 };
  34
  35 long int
  36 __lrintl (long double x)
  37 {
  38   int32_t j0;
  39   u_int64_t i0,i1;
  40   long double w;
  41   long double t;
  42   long int result;
  43   int sx;
  44
  45   GET_LDOUBLE_WORDS64 (i0, i1, x);
  46   j0 = ((i0 >> 48) & 0x7fff) - 0x3fff;
  47   sx = i0 >> 63;
  48   i0 &= 0x0000ffffffffffffLL;
  49   i0 |= 0x0001000000000000LL;
  50
  51   if (j0 < (int32_t) (8 * sizeof (long int)) - 1)
  52     {
  53       if (j0 < 48)
  54         {
  55 #if defined FE_INVALID || defined FE_INEXACT
  56           /* X < LONG_MAX + 1 implied by J0 < 31.  */
  57           if (sizeof (long int) == 4
  58               && x > (long double) LONG_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 == LONG_MAX ? FE_INEXACT : FE_INVALID);
  64             }
  65           else
  66 #endif
  67             {
  68               w = two112[sx] + x;
  69               t = w - two112[sx];
  70             }
  71           GET_LDOUBLE_WORDS64 (i0, i1, t);
  72           j0 = ((i0 >> 48) & 0x7fff) - 0x3fff;
  73           i0 &= 0x0000ffffffffffffLL;
  74           i0 |= 0x0001000000000000LL;
  75
  76           result = (j0 < 0 ? 0 : i0 >> (48 - j0));
  77         }
  78       else if (j0 >= 112)
  79         result = ((long int) i0 << (j0 - 48)) | (i1 << (j0 - 112));
  80       else
  81         {
  82 #if defined FE_INVALID || defined FE_INEXACT
  83           /* X < LONG_MAX + 1 implied by J0 < 63.  */
  84           if (sizeof (long int) == 8
  85               && x > (long double) LONG_MAX)
  86             {
  87               /* In the event of overflow we must raise the "invalid"
  88                  exception, but not "inexact".  */
  89               t = __nearbyintl (x);
  90               feraiseexcept (t == LONG_MAX ? FE_INEXACT : FE_INVALID);
  91             }
  92           else
  93 #endif
  94             {
  95               w = two112[sx] + x;
  96               t = w - two112[sx];
  97             }
  98           GET_LDOUBLE_WORDS64 (i0, i1, t);
  99           j0 = ((i0 >> 48) & 0x7fff) - 0x3fff;
 100           i0 &= 0x0000ffffffffffffLL;
 101           i0 |= 0x0001000000000000LL;
 102
 103           if (j0 == 48)
 104             result = (long int) i0;
 105           else
 106             result = ((long int) i0 << (j0 - 48)) | (i1 >> (112 - j0));
 107         }
 108     }
 109   else
 110     {
 111       /* The number is too large.  Unless it rounds to LONG_MIN,
 112          FE_INVALID must be raised and the return value is
 113          unspecified.  */
 114 #if defined FE_INVALID || defined FE_INEXACT
 115       if (x < (long double) LONG_MIN
 116           && x > (long double) LONG_MIN - 1.0L)
 117         {
 118           /* If truncation produces LONG_MIN, the cast will not raise
 119              the exception, but may raise "inexact".  */
 120           t = __nearbyintl (x);
 121           feraiseexcept (t == LONG_MIN ? FE_INEXACT : FE_INVALID);
 122           return LONG_MIN;
 123         }
 124       else if (FIX_LDBL_LONG_CONVERT_OVERFLOW && x != (long double) LONG_MIN)
 125         {
 126           feraiseexcept (FE_INVALID);
 127           return sx == 0 ? LONG_MAX : LONG_MIN;
 128         }
 129
 130 #endif
 131       return (long int) x;
 132     }
 133
 134   return sx ? -result : result;
 135 }
 136
 137 weak_alias (__lrintl, lrintl)