sysdeps/ieee754/ldbl-96/s_llroundl.c

   1 /* Round long double value to long long int.
   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 #include <fenv.h>
  20 #include <limits.h>
  21 #include <math.h>
  22
  23 #include <math_private.h>
  24 #include <libm-alias-ldouble.h>
  25
  26
  27 long long int
  28 __llroundl (long double x)
  29 {
  30   int32_t j0;
  31   uint32_t se, i1, i0;
  32   long long int result;
  33   int sign;
  34
  35   GET_LDOUBLE_WORDS (se, i0, i1, x);
  36   j0 = (se & 0x7fff) - 0x3fff;
  37   sign = (se & 0x8000) != 0 ? -1 : 1;
  38
  39   if (j0 < 31)
  40     {
  41       if (j0 < 0)
  42         return j0 < -1 ? 0 : sign;
  43       else
  44         {
  45           uint32_t j = i0 + (0x40000000 >> j0);
  46           if (j < i0)
  47             {
  48               j >>= 1;
  49               j |= 0x80000000;
  50               ++j0;
  51             }
  52
  53           result = j >> (31 - j0);
  54         }
  55     }
  56   else if (j0 < (int32_t) (8 * sizeof (long long int)) - 1)
  57     {
  58       if (j0 >= 63)
  59         result = (((long long int) i0 << 32) | i1) << (j0 - 63);
  60       else
  61         {
  62           uint32_t j = i1 + (0x80000000 >> (j0 - 31));
  63
  64           result = (long long int) i0;
  65           if (j < i1)
  66             ++result;
  67
  68           if (j0 > 31)
  69             {
  70               result = (result << (j0 - 31)) | (j >> (63 - j0));
  71 #ifdef FE_INVALID
  72               if (sign == 1 && result == LLONG_MIN)
  73                 /* Rounding brought the value out of range.  */
  74                 feraiseexcept (FE_INVALID);
  75 #endif
  76             }
  77         }
  78     }
  79   else
  80     {
  81       /* The number is too large.  It is left implementation defined
  82          what happens.  */
  83       return (long long int) x;
  84     }
  85
  86   return sign * result;
  87 }
  88
  89 libm_alias_ldouble (__llround, llround)