71 lines
1.5 KiB
C
71 lines
1.5 KiB
C
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/* __gmp_insert_double -- convert from array of mp_limb_t to double.
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Copyright (C) 1996 Free Software Foundation, Inc.
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This file is part of the GNU MP Library.
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The GNU MP Library is free software; you can redistribute it and/or modify
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it under the terms of the GNU Library General Public License as published by
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the Free Software Foundation; either version 2 of the License, or (at your
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option) any later version.
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The GNU MP Library is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public
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License for more details.
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You should have received a copy of the GNU Library General Public License
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along with the GNU MP Library; see the file COPYING.LIB. If not, write to
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the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
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MA 02111-1307, USA. */
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#include "gmp.h"
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#include "gmp-impl.h"
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#ifdef XDEBUG
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#undef _GMP_IEEE_FLOATS
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#endif
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#ifndef _GMP_IEEE_FLOATS
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#define _GMP_IEEE_FLOATS 0
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#endif
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double
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#if __STDC__
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__gmp_scale2 (double d, int exp)
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#else
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__gmp_scale2 (d, exp)
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double d;
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int exp;
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#endif
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{
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#if _GMP_IEEE_FLOATS
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{
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union ieee_double_extract x;
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x.d = d;
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x.s.exp += exp;
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return x.d;
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}
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#else
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{
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double factor, r;
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factor = 2.0;
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if (exp < 0)
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{
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factor = 0.5;
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exp = -exp;
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}
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r = d;
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while (exp != 0)
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{
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if ((exp & 1) != 0)
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r *= factor;
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factor *= factor;
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exp >>= 1;
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}
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return r;
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}
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#endif
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}
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