sysdeps/ieee754/ldbl-128/s_roundl.c

   1 /* Round long double to integer away from zero.
   2    Copyright (C) 1997-2024 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #define NO_MATH_REDIRECT
  20 #include <math.h>
  21
  22 #include <math_private.h>
  23 #include <libm-alias-ldouble.h>
  24 #include <math-use-builtins.h>
  25
  26
  27 _Float128
  28 __roundl (_Float128 x)
  29 {
  30 #if USE_ROUNDL_BUILTIN
  31   return __builtin_roundl (x);
  32 #else
  33   /* Use generic implementation.  */
  34   int32_t j0;
  35   uint64_t i1, i0;
  36
  37   GET_LDOUBLE_WORDS64 (i0, i1, x);
  38   j0 = ((i0 >> 48) & 0x7fff) - 0x3fff;
  39   if (j0 < 48)
  40     {
  41       if (j0 < 0)
  42         {
  43           i0 &= 0x8000000000000000ULL;
  44           if (j0 == -1)
  45             i0 |= 0x3fff000000000000LL;
  46           i1 = 0;
  47         }
  48       else
  49         {
  50           uint64_t i = 0x0000ffffffffffffLL >> j0;
  51           if (((i0 & i) | i1) == 0)
  52             /* X is integral.  */
  53             return x;
  54
  55           i0 += 0x0000800000000000LL >> j0;
  56           i0 &= ~i;
  57           i1 = 0;
  58         }
  59     }
  60   else if (j0 > 111)
  61     {
  62       if (j0 == 0x4000)
  63         /* Inf or NaN.  */
  64         return x + x;
  65       else
  66         return x;
  67     }
  68   else
  69     {
  70       uint64_t i = -1ULL >> (j0 - 48);
  71       if ((i1 & i) == 0)
  72         /* X is integral.  */
  73         return x;
  74
  75       uint64_t j = i1 + (1LL << (111 - j0));
  76       if (j < i1)
  77         i0 += 1;
  78       i1 = j;
  79       i1 &= ~i;
  80     }
  81
  82   SET_LDOUBLE_WORDS64 (x, i0, i1);
  83   return x;
  84 #endif /* ! USE_ROUNDL_BUILTIN  */
  85 }
  86 libm_alias_ldouble (__round, round)