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bfff8b1b | 1 | /* Copyright (C) 1995-2017 Free Software Foundation, Inc. |
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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 | |
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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. | |
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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 | |
41bdb6e2 | 12 | Lesser General Public License for more details. |
377a515b | 13 | |
41bdb6e2 | 14 | You should have received a copy of the GNU Lesser General Public |
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15 | License along with the GNU C Library; if not, see |
16 | <http://www.gnu.org/licenses/>. */ | |
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17 | |
18 | #include "gmp.h" | |
19 | #include "gmp-impl.h" | |
981993e1 | 20 | #include <ieee754.h> |
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21 | #include <float.h> |
22 | ||
23 | /* Convert a multi-precision integer of the needed number of bits (53 for | |
24 | double) and an integral power of two to a `double' in IEEE754 double- | |
a182affd | 25 | precision format. */ |
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26 | |
27 | double | |
28 | __mpn_construct_double (mp_srcptr frac_ptr, int expt, int negative) | |
29 | { | |
30 | union ieee754_double u; | |
a182affd | 31 | |
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32 | u.ieee.negative = negative; |
33 | u.ieee.exponent = expt + IEEE754_DOUBLE_BIAS; | |
34 | #if BITS_PER_MP_LIMB == 32 | |
35 | u.ieee.mantissa1 = frac_ptr[0]; | |
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36 | u.ieee.mantissa0 = frac_ptr[1] & (((mp_limb_t) 1 |
37 | << (DBL_MANT_DIG - 32)) - 1); | |
28f540f4 | 38 | #elif BITS_PER_MP_LIMB == 64 |
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39 | u.ieee.mantissa1 = frac_ptr[0] & (((mp_limb_t) 1 << 32) - 1); |
40 | u.ieee.mantissa0 = (frac_ptr[0] >> 32) & (((mp_limb_t) 1 | |
41 | << (DBL_MANT_DIG - 32)) - 1); | |
28f540f4 | 42 | #else |
c5d5d574 | 43 | # error "mp_limb size " BITS_PER_MP_LIMB "not accounted for" |
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44 | #endif |
45 | ||
46 | return u.d; | |
47 | } |