sysdeps/ieee754/ldbl-96/s_lrintl.c

   1 /* Round argument to nearest integral value according to current rounding
   2    direction.
   3    Copyright (C) 1997-2024 Free Software Foundation, Inc.
   4    This file is part of the GNU C Library.
   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    <https://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 static const long double two63[2] =
  28 {
  29   9.223372036854775808000000e+18, /* 0x403E, 0x00000000, 0x00000000 */
  30  -9.223372036854775808000000e+18  /* 0xC03E, 0x00000000, 0x00000000 */
  31 };
  32
  33
  34 long int
  35 __lrintl (long double x)
  36 {
  37   int32_t se,j0;
  38   uint32_t i0, i1;
  39   long int result;
  40   long double w;
  41   long double t;
  42   int sx;
  43
  44   GET_LDOUBLE_WORDS (se, i0, i1, x);
  45
  46   sx = (se >> 15) & 1;
  47   j0 = (se & 0x7fff) - 0x3fff;
  48
  49   if (j0 < 31)
  50     {
  51 #if defined FE_INVALID || defined FE_INEXACT
  52       /* X < LONG_MAX + 1 implied by J0 < 31.  */
  53       if (sizeof (long int) == 4
  54           && x > (long double) LONG_MAX)
  55         {
  56           /* In the event of overflow we must raise the "invalid"
  57              exception, but not "inexact".  */
  58           t = __nearbyintl (x);
  59           feraiseexcept (t == LONG_MAX ? FE_INEXACT : FE_INVALID);
  60         }
  61       else
  62 #endif
  63         {
  64           w = two63[sx] + x;
  65           t = w - two63[sx];
  66         }
  67       GET_LDOUBLE_WORDS (se, i0, i1, t);
  68       j0 = (se & 0x7fff) - 0x3fff;
  69
  70       result = (j0 < 0 ? 0 : i0 >> (31 - j0));
  71     }
  72   else if (j0 < (int32_t) (8 * sizeof (long int)) - 1)
  73     {
  74       if (j0 >= 63)
  75         result = ((long int) i0 << (j0 - 31)) | (i1 << (j0 - 63));
  76       else
  77         {
  78 #if defined FE_INVALID || defined FE_INEXACT
  79           /* X < LONG_MAX + 1 implied by J0 < 63.  */
  80           if (sizeof (long int) == 8
  81               && x > (long double) LONG_MAX)
  82             {
  83               /* In the event of overflow we must raise the "invalid"
  84                  exception, but not "inexact".  */
  85               t = __nearbyintl (x);
  86               feraiseexcept (t == LONG_MAX ? FE_INEXACT : FE_INVALID);
  87             }
  88           else
  89 #endif
  90             {
  91               w = two63[sx] + x;
  92               t = w - two63[sx];
  93             }
  94           GET_LDOUBLE_WORDS (se, i0, i1, t);
  95           j0 = (se & 0x7fff) - 0x3fff;
  96
  97           if (j0 == 31)
  98             result = (long int) i0;
  99           else
 100             result = ((long int) i0 << (j0 - 31)) | (i1 >> (63 - j0));
 101         }
 102     }
 103   else
 104     {
 105       /* The number is too large.  Unless it rounds to LONG_MIN,
 106          FE_INVALID must be raised and the return value is
 107          unspecified.  */
 108 #if defined FE_INVALID || defined FE_INEXACT
 109       if (sizeof (long int) == 4
 110           && x < (long double) LONG_MIN
 111           && x > (long double) LONG_MIN - 1.0L)
 112         {
 113           /* If truncation produces LONG_MIN, the cast will not raise
 114              the exception, but may raise "inexact".  */
 115           t = __nearbyintl (x);
 116           feraiseexcept (t == LONG_MIN ? FE_INEXACT : FE_INVALID);
 117           return LONG_MIN;
 118         }
 119 #endif
 120       return (long int) x;
 121     }
 122
 123   return sx ? -result : result;
 124 }
 125
 126 libm_alias_ldouble (__lrint, lrint)