/* Copyright (C) 1995-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Lesser General Public

   License as published by the Free Software Foundation; either

   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with the GNU C Library; if not, see

   <http://www.gnu.org/licenses/>.  */

#include "gmp.h"

#include "gmp-impl.h"

#include <ieee754.h>

#include <float.h>

/* Convert a multi-precision integer of the needed number of bits (53 for

   double) and an integral power of two to a `double' in IEEE754 double-

   precision format.  */

double

__mpn_construct_double (mp_srcptr frac_ptr, int expt, int negative)

{

  union ieee754_double u;

  u.ieee.negative = negative;

  u.ieee.exponent = expt + IEEE754_DOUBLE_BIAS;

#if BITS_PER_MP_LIMB == 32

  u.ieee.mantissa1 = frac_ptr[0];

  u.ieee.mantissa0 = frac_ptr[1] & (((mp_limb_t) 1

				     << (DBL_MANT_DIG - 32)) - 1);

#elif BITS_PER_MP_LIMB == 64

  u.ieee.mantissa1 = frac_ptr[0] & (((mp_limb_t) 1 << 32) - 1);

  u.ieee.mantissa0 = (frac_ptr[0] >> 32) & (((mp_limb_t) 1

					     << (DBL_MANT_DIG - 32)) - 1);

#else

  # error "mp_limb size " BITS_PER_MP_LIMB "not accounted for"

#endif

  return u.d;

}