sysdeps/ieee754/ldbl-128/s_lrintl.c

   1 /* Round argument to nearest integral value according to current rounding
   2    direction.
   3    Copyright (C) 1997-2019 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    <https://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 <libm-alias-ldouble.h>
  28 #include <fix-fp-int-convert-overflow.h>
  29
  30 static const _Float128 two112[2] =
  31 {
  32   L(5.19229685853482762853049632922009600E+33), /* 0x406F000000000000, 0 */
  33  L(-5.19229685853482762853049632922009600E+33)  /* 0xC06F000000000000, 0 */
  34 };
  35
  36 long int
  37 __lrintl (_Float128 x)
  38 {
  39   int32_t j0;
  40   uint64_t i0,i1;
  41   _Float128 w;
  42   _Float128 t;
  43   long int result;
  44   int sx;
  45
  46   GET_LDOUBLE_WORDS64 (i0, i1, x);
  47   j0 = ((i0 >> 48) & 0x7fff) - 0x3fff;
  48   sx = i0 >> 63;
  49   i0 &= 0x0000ffffffffffffLL;
  50   i0 |= 0x0001000000000000LL;
  51
  52   if (j0 < (int32_t) (8 * sizeof (long int)) - 1)
  53     {
  54       if (j0 < 48)
  55         {
  56 #if defined FE_INVALID || defined FE_INEXACT
  57           /* X < LONG_MAX + 1 implied by J0 < 31.  */
  58           if (sizeof (long int) == 4
  59               && x > (_Float128) LONG_MAX)
  60             {
  61               /* In the event of overflow we must raise the "invalid"
  62                  exception, but not "inexact".  */
  63               t = __nearbyintl (x);
  64               feraiseexcept (t == LONG_MAX ? FE_INEXACT : FE_INVALID);
  65             }
  66           else
  67 #endif
  68             {
  69               w = two112[sx] + x;
  70               t = w - two112[sx];
  71             }
  72           GET_LDOUBLE_WORDS64 (i0, i1, t);
  73           j0 = ((i0 >> 48) & 0x7fff) - 0x3fff;
  74           i0 &= 0x0000ffffffffffffLL;
  75           i0 |= 0x0001000000000000LL;
  76
  77           result = (j0 < 0 ? 0 : i0 >> (48 - j0));
  78         }
  79       else if (j0 >= 112)
  80         result = ((long int) i0 << (j0 - 48)) | (i1 << (j0 - 112));
  81       else
  82         {
  83 #if defined FE_INVALID || defined FE_INEXACT
  84           /* X < LONG_MAX + 1 implied by J0 < 63.  */
  85           if (sizeof (long int) == 8
  86               && x > (_Float128) LONG_MAX)
  87             {
  88               /* In the event of overflow we must raise the "invalid"
  89                  exception, but not "inexact".  */
  90               t = __nearbyintl (x);
  91               feraiseexcept (t == LONG_MAX ? FE_INEXACT : FE_INVALID);
  92             }
  93           else
  94 #endif
  95             {
  96               w = two112[sx] + x;
  97               t = w - two112[sx];
  98             }
  99           GET_LDOUBLE_WORDS64 (i0, i1, t);
 100           j0 = ((i0 >> 48) & 0x7fff) - 0x3fff;
 101           i0 &= 0x0000ffffffffffffLL;
 102           i0 |= 0x0001000000000000LL;
 103
 104           if (j0 == 48)
 105             result = (long int) i0;
 106           else
 107             result = ((long int) i0 << (j0 - 48)) | (i1 >> (112 - j0));
 108         }
 109     }
 110   else
 111     {
 112       /* The number is too large.  Unless it rounds to LONG_MIN,
 113          FE_INVALID must be raised and the return value is
 114          unspecified.  */
 115 #if defined FE_INVALID || defined FE_INEXACT
 116       if (x < (_Float128) LONG_MIN
 117           && x > (_Float128) LONG_MIN - 1)
 118         {
 119           /* If truncation produces LONG_MIN, the cast will not raise
 120              the exception, but may raise "inexact".  */
 121           t = __nearbyintl (x);
 122           feraiseexcept (t == LONG_MIN ? FE_INEXACT : FE_INVALID);
 123           return LONG_MIN;
 124         }
 125       else if (FIX_LDBL_LONG_CONVERT_OVERFLOW && x != (_Float128) LONG_MIN)
 126         {
 127           feraiseexcept (FE_INVALID);
 128           return sx == 0 ? LONG_MAX : LONG_MIN;
 129         }
 130
 131 #endif
 132       return (long int) x;
 133     }
 134
 135   return sx ? -result : result;
 136 }
 137
 138 libm_alias_ldouble (__lrint, lrint)