sysdeps/ieee754/ldbl-128/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 #include <fix-fp-int-convert-overflow.h>
  27 #include <math-use-builtins.h>
  28
  29
  30 long int
  31 __lrintl (_Float128 x)
  32 {
  33 #if USE_LRINTL_BUILTIN
  34   return __builtin_lrintl (x);
  35 #else
  36   /* Use generic implementation. */
  37   static const _Float128 two112[2] =
  38   {
  39     L(5.19229685853482762853049632922009600E+33), /* 0x406F000000000000, 0 */
  40    L(-5.19229685853482762853049632922009600E+33)  /* 0xC06F000000000000, 0 */
  41   };
  42
  43   int32_t j0;
  44   uint64_t i0,i1;
  45   _Float128 w;
  46   _Float128 t;
  47   long int result;
  48   int sx;
  49
  50   GET_LDOUBLE_WORDS64 (i0, i1, x);
  51   j0 = ((i0 >> 48) & 0x7fff) - 0x3fff;
  52   sx = i0 >> 63;
  53   i0 &= 0x0000ffffffffffffLL;
  54   i0 |= 0x0001000000000000LL;
  55
  56   if (j0 < (int32_t) (8 * sizeof (long int)) - 1)
  57     {
  58       if (j0 < 48)
  59         {
  60 #if defined FE_INVALID || defined FE_INEXACT
  61           /* X < LONG_MAX + 1 implied by J0 < 31.  */
  62           if (sizeof (long int) == 4
  63               && x > (_Float128) LONG_MAX)
  64             {
  65               /* In the event of overflow we must raise the "invalid"
  66                  exception, but not "inexact".  */
  67               t = __nearbyintl (x);
  68               feraiseexcept (t == LONG_MAX ? FE_INEXACT : FE_INVALID);
  69             }
  70           else
  71 #endif
  72             {
  73               w = two112[sx] + x;
  74               t = w - two112[sx];
  75             }
  76           GET_LDOUBLE_WORDS64 (i0, i1, t);
  77           j0 = ((i0 >> 48) & 0x7fff) - 0x3fff;
  78           i0 &= 0x0000ffffffffffffLL;
  79           i0 |= 0x0001000000000000LL;
  80
  81           result = (j0 < 0 ? 0 : i0 >> (48 - j0));
  82         }
  83       else if (j0 >= 112)
  84         result = ((long int) i0 << (j0 - 48)) | (i1 << (j0 - 112));
  85       else
  86         {
  87 #if defined FE_INVALID || defined FE_INEXACT
  88           /* X < LONG_MAX + 1 implied by J0 < 63.  */
  89           if (sizeof (long int) == 8
  90               && x > (_Float128) LONG_MAX)
  91             {
  92               /* In the event of overflow we must raise the "invalid"
  93                  exception, but not "inexact".  */
  94               t = __nearbyintl (x);
  95               feraiseexcept (t == LONG_MAX ? FE_INEXACT : FE_INVALID);
  96             }
  97           else
  98 #endif
  99             {
 100               w = two112[sx] + x;
 101               t = w - two112[sx];
 102             }
 103           GET_LDOUBLE_WORDS64 (i0, i1, t);
 104           j0 = ((i0 >> 48) & 0x7fff) - 0x3fff;
 105           i0 &= 0x0000ffffffffffffLL;
 106           i0 |= 0x0001000000000000LL;
 107
 108           if (j0 == 48)
 109             result = (long int) i0;
 110           else
 111             result = ((long int) i0 << (j0 - 48)) | (i1 >> (112 - j0));
 112         }
 113     }
 114   else
 115     {
 116       /* The number is too large.  Unless it rounds to LONG_MIN,
 117          FE_INVALID must be raised and the return value is
 118          unspecified.  */
 119 #if defined FE_INVALID || defined FE_INEXACT
 120       if (x < (_Float128) LONG_MIN
 121           && x > (_Float128) LONG_MIN - 1)
 122         {
 123           /* If truncation produces LONG_MIN, the cast will not raise
 124              the exception, but may raise "inexact".  */
 125           t = __nearbyintl (x);
 126           feraiseexcept (t == LONG_MIN ? FE_INEXACT : FE_INVALID);
 127           return LONG_MIN;
 128         }
 129       else if (FIX_LDBL_LONG_CONVERT_OVERFLOW && x != (_Float128) LONG_MIN)
 130         {
 131           feraiseexcept (FE_INVALID);
 132           return sx == 0 ? LONG_MAX : LONG_MIN;
 133         }
 134
 135 #endif
 136       return (long int) x;
 137     }
 138
 139   return sx ? -result : result;
 140 #endif /* ! USE_LRINTL_BUILTIN  */
 141 }
 142
 143 libm_alias_ldouble (__lrint, lrint)