1/* Convert a number in multi-precision format to _Float128.
2 Copyright (C) 2017-2020 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}
55