sysdeps/ieee754/ldbl-96/mpn2ldbl.c

   1 /* Copyright (C) 1995,1996,1997,1998,2002,2003 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, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    02111-1307 USA.  */
  18
  19 #include "gmp.h"
  20 #include "gmp-impl.h"
  21 #include <ieee754.h>
  22 #include <float.h>
  23 #include <math.h>
  24
  25 /* Convert a multi-precision integer of the needed number of bits (64 for
  26    long double) and an integral power of two to a `long double' in IEEE854
  27    extended-precision format.  */
  28
  29 long double
  30 __mpn_construct_long_double (mp_srcptr frac_ptr, int expt, int sign)
  31 {
  32   union ieee854_long_double u;
  33
  34   u.ieee.negative = sign;
  35   u.ieee.exponent = expt + IEEE854_LONG_DOUBLE_BIAS;
  36 #if BITS_PER_MP_LIMB == 32
  37   u.ieee.mantissa1 = frac_ptr[0];
  38   u.ieee.mantissa0 = frac_ptr[1];
  39 #elif BITS_PER_MP_LIMB == 64
  40   u.ieee.mantissa1 = frac_ptr[0] & (((mp_limb_t) 1 << 32) - 1);
  41   u.ieee.mantissa0 = frac_ptr[0] >> 32;
  42 #else
  43   #error "mp_limb size " BITS_PER_MP_LIMB "not accounted for"
  44 #endif
  45
  46   return u.d;
  47 }