e554550755
for file in $(find -name \*.h ) ; do sed -e "s/#include \"gmp\.h\"/#include \"mpir.h\"/g" $file > temp ; mv temp $file ; done for file in $(find -name \*.cc) ; do sed -e "s/#include \"gmp\.h\"/#include \"mpir.h\"/g" $file > temp ; mv temp $file ; done
118 lines
3.0 KiB
C
118 lines
3.0 KiB
C
/* mpn_gcd_1 -- mpn and limb greatest common divisor.
|
|
|
|
Copyright 1994, 1996, 2000, 2001 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 "mpir.h"
|
|
#include "gmp-impl.h"
|
|
#include "longlong.h"
|
|
|
|
|
|
/* Does not work for U == 0 or V == 0. It would be tough to make it work for
|
|
V == 0 since gcd(x,0) = x, and U does not generally fit in an mp_limb_t.
|
|
|
|
The threshold for doing u%v when size==1 will vary by CPU according to
|
|
the speed of a division and the code generated for the main loop. Any
|
|
tuning for this is left to a CPU specific implementation. */
|
|
|
|
mp_limb_t
|
|
mpn_gcd_1 (mp_srcptr up, mp_size_t size, mp_limb_t vlimb)
|
|
{
|
|
mp_limb_t ulimb;
|
|
unsigned long zero_bits, u_low_zero_bits;
|
|
|
|
ASSERT (size >= 1);
|
|
ASSERT (vlimb != 0);
|
|
ASSERT_MPN_NONZERO_P (up, size);
|
|
|
|
ulimb = up[0];
|
|
|
|
/* Need vlimb odd for modexact, want it odd to get common zeros. */
|
|
count_trailing_zeros (zero_bits, vlimb);
|
|
vlimb >>= zero_bits;
|
|
|
|
if (size > 1)
|
|
{
|
|
/* Must get common zeros before the mod reduction. If ulimb==0 then
|
|
vlimb already gives the common zeros. */
|
|
if (ulimb != 0)
|
|
{
|
|
count_trailing_zeros (u_low_zero_bits, ulimb);
|
|
zero_bits = MIN (zero_bits, u_low_zero_bits);
|
|
}
|
|
|
|
ulimb = MPN_MOD_OR_MODEXACT_1_ODD (up, size, vlimb);
|
|
if (ulimb == 0)
|
|
goto done;
|
|
|
|
goto strip_u_maybe;
|
|
}
|
|
|
|
/* size==1, so up[0]!=0 */
|
|
count_trailing_zeros (u_low_zero_bits, ulimb);
|
|
ulimb >>= u_low_zero_bits;
|
|
zero_bits = MIN (zero_bits, u_low_zero_bits);
|
|
|
|
/* make u bigger */
|
|
if (vlimb > ulimb)
|
|
MP_LIMB_T_SWAP (ulimb, vlimb);
|
|
|
|
/* if u is much bigger than v, reduce using a division rather than
|
|
chipping away at it bit-by-bit */
|
|
if ((ulimb >> 16) > vlimb)
|
|
{
|
|
ulimb %= vlimb;
|
|
if (ulimb == 0)
|
|
goto done;
|
|
goto strip_u_maybe;
|
|
}
|
|
|
|
while (ulimb != vlimb)
|
|
{
|
|
ASSERT (ulimb & 1);
|
|
ASSERT (vlimb & 1);
|
|
|
|
if (ulimb > vlimb)
|
|
{
|
|
ulimb -= vlimb;
|
|
do
|
|
{
|
|
ulimb >>= 1;
|
|
ASSERT (ulimb != 0);
|
|
strip_u_maybe:
|
|
;
|
|
}
|
|
while ((ulimb & 1) == 0);
|
|
}
|
|
else /* vlimb > ulimb. */
|
|
{
|
|
vlimb -= ulimb;
|
|
do
|
|
{
|
|
vlimb >>= 1;
|
|
ASSERT (vlimb != 0);
|
|
}
|
|
while ((vlimb & 1) == 0);
|
|
}
|
|
}
|
|
|
|
done:
|
|
return vlimb << zero_bits;
|
|
}
|