1 /* Copyright (C) 1995-2022 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 (64 for 25 long double) and an integral power of two to a `long double' in IEEE854 26 extended-precision format. */ 27 28 long double __mpn_construct_long_double(mp_srcptr frac_ptr,int expt,int sign)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.mantissa1 = frac_ptr[0]; 37 u.ieee.mantissa0 = frac_ptr[1]; 38 #elif BITS_PER_MP_LIMB == 64 39 u.ieee.mantissa1 = frac_ptr[0] & (((mp_limb_t) 1 << 32) - 1); 40 u.ieee.mantissa0 = frac_ptr[0] >> 32; 41 #else 42 #error "mp_limb size " BITS_PER_MP_LIMB "not accounted for" 43 #endif 44 45 return u.d; 46 } 47