1  /* Round long double value to long int.
       2     Copyright (C) 1997-2023 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 int
      28  __lroundl (long double x)
      29  {
      30    int32_t j0;
      31    uint32_t se, i1, i0;
      32    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  #ifdef FE_INVALID
      55  	  if (sizeof (long int) == 4
      56  	      && sign == 1
      57  	      && result == LONG_MIN)
      58  	    /* Rounding brought the value out of range.  */
      59  	    feraiseexcept (FE_INVALID);
      60  #endif
      61  	}
      62      }
      63    else if (j0 < (int32_t) (8 * sizeof (long int)) - 1)
      64      {
      65        if (j0 >= 63)
      66  	result = ((long int) i0 << (j0 - 31)) | (i1 << (j0 - 63));
      67        else
      68  	{
      69  	  uint32_t j = i1 + (0x80000000 >> (j0 - 31));
      70  	  unsigned long int ures = i0;
      71  
      72  	  if (j < i1)
      73  	    ++ures;
      74  
      75  	  if (j0 == 31)
      76  	    result = ures;
      77  	  else
      78  	    {
      79  	      result = (ures << (j0 - 31)) | (j >> (63 - j0));
      80  #ifdef FE_INVALID
      81  	      if (sizeof (long int) == 8
      82  		  && sign == 1
      83  		  && result == LONG_MIN)
      84  		/* Rounding brought the value out of range.  */
      85  		feraiseexcept (FE_INVALID);
      86  #endif
      87  	    }
      88  	}
      89      }
      90    else
      91      {
      92        /* The number is too large.  Unless it rounds to LONG_MIN,
      93  	 FE_INVALID must be raised and the return value is
      94  	 unspecified.  */
      95  #ifdef FE_INVALID
      96        if (sizeof (long int) == 4
      97  	  && x <= (long double) LONG_MIN - 0.5L)
      98  	{
      99  	  /* If truncation produces LONG_MIN, the cast will not raise
     100  	     the exception, but may raise "inexact".  */
     101  	  feraiseexcept (FE_INVALID);
     102  	  return LONG_MIN;
     103  	}
     104  #endif
     105        return (long int) x;
     106      }
     107  
     108    return sign * result;
     109  }
     110  
     111  libm_alias_ldouble (__lround, lround)