1  /* Copyright (C) 1995-2023 Free Software Foundation, Inc.
       2     This file is part of the GNU C Library.
       3  
       4     The GNU C Library is free software; you can redistribute it and/or
       5     modify it under the terms of the GNU Lesser General Public
       6     License as published by the Free Software Foundation; either
       7     version 2.1 of the License, or (at your option) any later version.
       8  
       9     The GNU C Library is distributed in the hope that it will be useful,
      10     but WITHOUT ANY WARRANTY; without even the implied warranty of
      11     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      12     Lesser General Public License for more details.
      13  
      14     You should have received a copy of the GNU Lesser General Public
      15     License along with the GNU C Library; if not, see
      16     <https://www.gnu.org/licenses/>.  */
      17  
      18  #include "gmp.h"
      19  #include "gmp-impl.h"
      20  #include <ieee754.h>
      21  #include <float.h>
      22  #include <math.h>
      23  
      24  /* Convert a multi-precision integer of the needed number of bits (113 for
      25     long double) and an integral power of two to a `long double' in IEEE854
      26     quad-precision format.  */
      27  
      28  long double
      29  __mpn_construct_long_double (mp_srcptr frac_ptr, int expt, int sign)
      30  {
      31    union ieee854_long_double u;
      32  
      33    u.ieee.negative = sign;
      34    u.ieee.exponent = expt + IEEE854_LONG_DOUBLE_BIAS;
      35  #if BITS_PER_MP_LIMB == 32
      36    u.ieee.mantissa3 = frac_ptr[0];
      37    u.ieee.mantissa2 = frac_ptr[1];
      38    u.ieee.mantissa1 = frac_ptr[2];
      39    u.ieee.mantissa0 = frac_ptr[3] & (((mp_limb_t) 1
      40  				     << (LDBL_MANT_DIG - 96)) - 1);
      41  #elif BITS_PER_MP_LIMB == 64
      42    u.ieee.mantissa3 = frac_ptr[0] & (((mp_limb_t) 1 << 32) - 1);
      43    u.ieee.mantissa2 = frac_ptr[0] >> 32;
      44    u.ieee.mantissa1 = frac_ptr[1] & (((mp_limb_t) 1 << 32) - 1);
      45    u.ieee.mantissa0 = (frac_ptr[1] >> 32) & (((mp_limb_t) 1
      46  					     << (LDBL_MANT_DIG - 96)) - 1);
      47  #else
      48    #error "mp_limb size " BITS_PER_MP_LIMB "not accounted for"
      49  #endif
      50  
      51    return u.d;
      52  }