78 lines
2.0 KiB
C
78 lines
2.0 KiB
C
/* mpz_gcd_ui -- Calculate the greatest common divisior of two integers.
|
|
|
|
Copyright 1994, 1996, 1999, 2000, 2001, 2002, 2003, 2004 Free Software
|
|
Foundation, Inc.
|
|
|
|
This file is part of the GNU MP Library.
|
|
|
|
The GNU MP Library is free software; you can redistribute it and/or modify
|
|
it under the terms of the GNU Lesser General Public License as published by
|
|
the Free Software Foundation; either version 2.1 of the License, or (at your
|
|
option) any later version.
|
|
|
|
The GNU MP Library is distributed in the hope that it will be useful, but
|
|
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
|
|
or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
|
|
License for more details.
|
|
|
|
You should have received a copy of the GNU Lesser General Public License
|
|
along with the GNU MP Library; see the file COPYING.LIB. If not, write to
|
|
the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
|
|
MA 02110-1301, USA. */
|
|
|
|
#include <stdio.h> /* for NULL */
|
|
#include "mpir.h"
|
|
#include "gmp-impl.h"
|
|
|
|
mpir_ui
|
|
mpz_gcd_ui (mpz_ptr w, mpz_srcptr u, mpir_ui v)
|
|
{
|
|
mp_size_t un;
|
|
mp_limb_t res;
|
|
|
|
#if BITS_PER_UI > GMP_NUMB_BITS /* avoid warnings about shift amount */
|
|
if (v > GMP_NUMB_MAX)
|
|
{
|
|
mpz_t vz;
|
|
mp_limb_t vlimbs[2];
|
|
vlimbs[0] = v & GMP_NUMB_MASK;
|
|
vlimbs[1] = v >> GMP_NUMB_BITS;
|
|
PTR(vz) = vlimbs;
|
|
SIZ(vz) = 2;
|
|
mpz_gcd (w, u, vz);
|
|
/* because v!=0 we will have w<=v hence fitting a ulong */
|
|
ASSERT (mpz_fits_ui_p (w));
|
|
return mpz_get_ui (w);
|
|
}
|
|
#endif
|
|
|
|
un = ABSIZ(u);
|
|
|
|
if (un == 0)
|
|
res = v;
|
|
else if (v == 0)
|
|
{
|
|
if (w != NULL)
|
|
{
|
|
if (u != w)
|
|
{
|
|
MPZ_REALLOC (w, un);
|
|
MPN_COPY (PTR(w), PTR(u), un);
|
|
}
|
|
SIZ(w) = un;
|
|
}
|
|
/* Return u if it fits a ulong, otherwise 0. */
|
|
res = PTR(u)[0];
|
|
return (un == 1 && res <= ULONG_MAX ? res : 0);
|
|
}
|
|
else
|
|
res = mpn_gcd_1 (PTR(u), un, (mp_limb_t) v);
|
|
|
|
if (w != NULL)
|
|
{
|
|
PTR(w)[0] = res;
|
|
SIZ(w) = res != 0;
|
|
}
|
|
return res;
|
|
}
|