| /* 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; |
| } |