1  /* Convert a number in multi-precision format to _Float128.
       2     Copyright (C) 2017-2023 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 "gmp.h"
      20  #include "gmp-impl.h"
      21  #include <float.h>
      22  #include <math.h>
      23  
      24  #include "ieee754_float128.h"
      25  
      26  /* Convert a multi-precision integer of the needed number of bits (113 for
      27     binary128) and an integral power of two to a `_Float128' in IEEE854
      28     quad-precision format.  */
      29  
      30  _Float128
      31  __mpn_construct_float128 (mp_srcptr frac_ptr, int expt, int sign)
      32  {
      33    union ieee854_float128 u;
      34  
      35    u.ieee.negative = sign;
      36    u.ieee.exponent = expt + IEEE854_FLOAT128_BIAS;
      37  #if BITS_PER_MP_LIMB == 32
      38    u.ieee.mantissa3 = frac_ptr[0];
      39    u.ieee.mantissa2 = frac_ptr[1];
      40    u.ieee.mantissa1 = frac_ptr[2];
      41    u.ieee.mantissa0 = frac_ptr[3] & (((mp_limb_t) 1
      42  				     << (FLT128_MANT_DIG - 96)) - 1);
      43  #elif BITS_PER_MP_LIMB == 64
      44    u.ieee.mantissa3 = frac_ptr[0] & (((mp_limb_t) 1 << 32) - 1);
      45    u.ieee.mantissa2 = frac_ptr[0] >> 32;
      46    u.ieee.mantissa1 = frac_ptr[1] & (((mp_limb_t) 1 << 32) - 1);
      47    u.ieee.mantissa0 = (frac_ptr[1] >> 32) & (((mp_limb_t) 1
      48  					     << (FLT128_MANT_DIG - 96)) - 1);
      49  #else
      50    #error "mp_limb size " BITS_PER_MP_LIMB "not accounted for"
      51  #endif
      52  
      53    return u.d;
      54  }