61 lines
1.8 KiB
C
61 lines
1.8 KiB
C
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/* mpz_sizeinbase(x, base) -- return an approximation to the number of
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character the integer X would have printed in base BASE. The
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approximation is never too small.
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Copyright (C) 1991, 1993, 1994, 1995 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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#include "longlong.h"
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size_t
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#if __STDC__
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mpz_sizeinbase (mpz_srcptr x, int base)
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#else
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mpz_sizeinbase (x, base)
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mpz_srcptr x;
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int base;
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#endif
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{
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mp_size_t size = ABS (x->_mp_size);
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int lb_base, cnt;
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size_t totbits;
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/* Special case for X == 0. */
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if (size == 0)
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return 1;
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/* Calculate the total number of significant bits of X. */
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count_leading_zeros (cnt, x->_mp_d[size - 1]);
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totbits = size * BITS_PER_MP_LIMB - cnt;
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if ((base & (base - 1)) == 0)
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{
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/* Special case for powers of 2, giving exact result. */
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count_leading_zeros (lb_base, base);
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lb_base = BITS_PER_MP_LIMB - lb_base - 1;
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return (totbits + lb_base - 1) / lb_base;
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}
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else
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return (size_t) (totbits * __mp_bases[base].chars_per_bit_exactly) + 1;
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}
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