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  #include <fix-fp-int-convert-overflow.h>
      26  
      27  long int
      28  __lroundl (_Float128 x)
      29  {
      30    int64_t j0;
      31    uint64_t i1, i0;
      32    long int result;
      33    int sign;
      34  
      35    GET_LDOUBLE_WORDS64 (i0, i1, x);
      36    j0 = ((i0 >> 48) & 0x7fff) - 0x3fff;
      37    sign = (i0 & 0x8000000000000000ULL) != 0 ? -1 : 1;
      38    i0 &= 0x0000ffffffffffffLL;
      39    i0 |= 0x0001000000000000LL;
      40  
      41    if (j0 < (int32_t) (8 * sizeof (long int)) - 1)
      42      {
      43        if (j0 < 48)
      44  	{
      45  	  if (j0 < 0)
      46  	    return j0 < -1 ? 0 : sign;
      47  	  else
      48  	    {
      49  	      i0 += 0x0000800000000000LL >> j0;
      50  	      result = i0 >> (48 - j0);
      51  #ifdef FE_INVALID
      52  	      if (sizeof (long int) == 4
      53  		  && sign == 1
      54  		  && result == LONG_MIN)
      55  		/* Rounding brought the value out of range.  */
      56  		feraiseexcept (FE_INVALID);
      57  #endif
      58  	    }
      59  	}
      60        else if (j0 >= 112)
      61  	result = ((long int) i0 << (j0 - 48)) | (i1 << (j0 - 112));
      62        else
      63  	{
      64  	  uint64_t j = i1 + (0x8000000000000000ULL >> (j0 - 48));
      65  	  if (j < i1)
      66  	    ++i0;
      67  
      68  	  if (j0 == 48)
      69  	    result = (long int) i0;
      70  	  else
      71  	    {
      72  	      result = ((long int) i0 << (j0 - 48)) | (j >> (112 - j0));
      73  #ifdef FE_INVALID
      74  	      if (sizeof (long int) == 8
      75  		  && sign == 1
      76  		  && result == LONG_MIN)
      77  		/* Rounding brought the value out of range.  */
      78  		feraiseexcept (FE_INVALID);
      79  #endif
      80  	    }
      81  	}
      82      }
      83    else
      84      {
      85        /* The number is too large.  Unless it rounds to LONG_MIN,
      86  	 FE_INVALID must be raised and the return value is
      87  	 unspecified.  */
      88  #ifdef FE_INVALID
      89        if (FIX_LDBL_LONG_CONVERT_OVERFLOW
      90  	  && !(sign == -1 && x > (_Float128) LONG_MIN - L(0.5)))
      91  	{
      92  	  feraiseexcept (FE_INVALID);
      93  	  return sign == 1 ? LONG_MAX : LONG_MIN;
      94  	}
      95        else if (!FIX_LDBL_LONG_CONVERT_OVERFLOW
      96  	       && x <= (_Float128) LONG_MIN - L(0.5))
      97  	{
      98  	  /* If truncation produces LONG_MIN, the cast will not raise
      99  	     the exception, but may raise "inexact".  */
     100  	  feraiseexcept (FE_INVALID);
     101  	  return LONG_MIN;
     102  	}
     103  #endif
     104        /* The number is too large.  It is left implementation defined
     105  	 what happens.  */
     106        return (long int) x;
     107      }
     108  
     109    return sign * result;
     110  }
     111  
     112  libm_alias_ldouble (__lround, lround)