mirror of
https://github.com/vale981/arb
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83 lines
1.6 KiB
C
83 lines
1.6 KiB
C
/*
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Copyright (C) 2014 Fredrik Johansson
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This file is part of Arb.
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Arb is free software: you can redistribute it and/or modify it under
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the terms of the GNU Lesser General Public License (LGPL) as published
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by the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version. See <http://www.gnu.org/licenses/>.
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*/
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#include "flint/double_extras.h"
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#include "arf.h"
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void
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arf_set_d(arf_t x, double v)
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{
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#if FLINT_BITS == 64
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mp_limb_t h, sign, exp, frac;
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slong real_exp, real_man;
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union { double uf; mp_limb_t ul; } u;
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u.uf = v;
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h = u.ul;
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sign = h >> 63;
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exp = (h << 1) >> 53;
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frac = (h << 12) >> 12;
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if (exp == 0 && frac == 0)
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{
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arf_zero(x);
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return;
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}
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else if (exp == 0x7ff)
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{
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if (frac == 0)
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{
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if (sign)
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arf_neg_inf(x);
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else
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arf_pos_inf(x);
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}
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else
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{
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arf_nan(x);
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}
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return;
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}
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/* handle subnormals */
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if (exp == 0 && frac != 0)
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{
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int exp2;
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v = frexp(v, &exp2);
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u.uf = v;
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h = u.ul;
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sign = h >> 63;
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exp = (h << 1) >> 53;
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frac = (h << 12) >> 12;
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exp += exp2;
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}
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real_exp = exp - 1023 - 52;
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frac |= (UWORD(1) << 52);
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real_man = sign ? (-frac) : frac;
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arf_set_si_2exp_si(x, real_man, real_exp);
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#else
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mpfr_t t;
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mp_limb_t tmp[2];
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t->_mpfr_prec = 53;
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t->_mpfr_sign = 1;
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t->_mpfr_exp = 0;
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t->_mpfr_d = tmp;
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mpfr_set_d(t, v, MPFR_RNDD);
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arf_set_mpfr(x, t);
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#endif
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}
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