78 lines
2.1 KiB
C
78 lines
2.1 KiB
C
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/* mpz_gcd_ui -- Calculate the greatest common divisior of two integers.
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Copyright 1994, 1996, 1999, 2000, 2001, 2002, 2003, 2004 Free Software
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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 Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 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 Lesser General Public
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License for more details.
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You should have received a copy of the GNU Lesser 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., 51 Franklin Street, Fifth Floor, Boston,
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MA 02110-1301, USA. */
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#include <stdio.h> /* for NULL */
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#include "gmp.h"
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#include "gmp-impl.h"
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unsigned long int
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mpz_gcd_ui (mpz_ptr w, mpz_srcptr u, unsigned long int v)
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{
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mp_size_t un;
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mp_limb_t res;
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#if BITS_PER_ULONG > GMP_NUMB_BITS /* avoid warnings about shift amount */
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if (v > GMP_NUMB_MAX)
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{
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mpz_t vz;
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mp_limb_t vlimbs[2];
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vlimbs[0] = v & GMP_NUMB_MASK;
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vlimbs[1] = v >> GMP_NUMB_BITS;
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PTR(vz) = vlimbs;
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SIZ(vz) = 2;
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mpz_gcd (w, u, vz);
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/* because v!=0 we will have w<=v hence fitting a ulong */
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ASSERT (mpz_fits_ulong_p (w));
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return mpz_get_ui (w);
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}
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#endif
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un = ABSIZ(u);
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if (un == 0)
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res = v;
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else if (v == 0)
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{
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if (w != NULL)
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{
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if (u != w)
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{
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MPZ_REALLOC (w, un);
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MPN_COPY (PTR(w), PTR(u), un);
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}
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SIZ(w) = un;
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}
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/* Return u if it fits a ulong, otherwise 0. */
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res = PTR(u)[0];
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return (un == 1 && res <= ULONG_MAX ? res : 0);
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}
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else
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res = mpn_gcd_1 (PTR(u), un, (mp_limb_t) v);
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if (w != NULL)
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{
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PTR(w)[0] = res;
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SIZ(w) = res != 0;
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}
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return res;
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}
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