sysdeps/ieee754/ldbl-128/s_llrintl.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 long int
  31 __llrintl (_Float128 x)
  32 {
  33 #if USE_LLRINTL_BUILTIN
  34   return __builtin_llrintl (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 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 long int)) - 1)
  57     {
  58 #if defined FE_INVALID || defined FE_INEXACT
  59       /* X < LLONG_MAX + 1 implied by J0 < 63.  */
  60       if (x > (_Float128) LLONG_MAX)
  61         {
  62           /* In the event of overflow we must raise the "invalid"
  63              exception, but not "inexact".  */
  64           t = __nearbyintl (x);
  65           feraiseexcept (t == LLONG_MAX ? FE_INEXACT : FE_INVALID);
  66         }
  67       else
  68 #endif
  69         {
  70           w = two112[sx] + x;
  71           t = w - two112[sx];
  72         }
  73       GET_LDOUBLE_WORDS64 (i0, i1, t);
  74       j0 = ((i0 >> 48) & 0x7fff) - 0x3fff;
  75       i0 &= 0x0000ffffffffffffLL;
  76       i0 |= 0x0001000000000000LL;
  77
  78       if (j0 < 0)
  79         result = 0;
  80       else if (j0 <= 48)
  81         result = i0 >> (48 - j0);
  82       else
  83         result = ((long long int) i0 << (j0 - 48)) | (i1 >> (112 - j0));
  84     }
  85   else
  86     {
  87       /* The number is too large.  Unless it rounds to LLONG_MIN,
  88          FE_INVALID must be raised and the return value is
  89          unspecified.  */
  90 #if defined FE_INVALID || defined FE_INEXACT
  91       if (x < (_Float128) LLONG_MIN
  92           && x > (_Float128) LLONG_MIN - 1)
  93         {
  94           /* If truncation produces LLONG_MIN, the cast will not raise
  95              the exception, but may raise "inexact".  */
  96           t = __nearbyintl (x);
  97           feraiseexcept (t == LLONG_MIN ? FE_INEXACT : FE_INVALID);
  98           return LLONG_MIN;
  99         }
 100       else if (FIX_LDBL_LLONG_CONVERT_OVERFLOW && x != (_Float128) LLONG_MIN)
 101         {
 102           feraiseexcept (FE_INVALID);
 103           return sx == 0 ? LLONG_MAX : LLONG_MIN;
 104         }
 105
 106 #endif
 107       return (long long int) x;
 108     }
 109
 110   return sx ? -result : result;
 111 #endif /* ! USE_LLRINTL_BUILTIN  */
 112 }
 113
 114 libm_alias_ldouble (__llrint, llrint)