55 lines
1.5 KiB
C
55 lines
1.5 KiB
C
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/* double mpz_get_d (mpz_t src) -- Return the double approximation to SRC.
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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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double
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#if __STDC__
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mpz_get_d (mpz_srcptr src)
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#else
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mpz_get_d (src)
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mpz_srcptr src;
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#endif
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{
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double res;
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mp_size_t size, i, n_limbs_to_use;
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int negative;
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mp_ptr qp;
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size = SIZ(src);
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if (size == 0)
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return 0.0;
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negative = size < 0;
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size = ABS (size);
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qp = PTR(src);
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res = qp[size - 1];
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n_limbs_to_use = MIN (LIMBS_PER_DOUBLE, size);
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for (i = 2; i <= n_limbs_to_use; i++)
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res = res * MP_BASE_AS_DOUBLE + qp[size - i];
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res = __gmp_scale2 (res, (size - n_limbs_to_use) * BITS_PER_MP_LIMB);
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return negative ? -res : res;
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}
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