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
135 lines
3.1 KiB
C
135 lines
3.1 KiB
C
/* mpn_udiv_w_sdiv -- implement udiv_qrnnd on machines with only signed
|
|
division.
|
|
|
|
Contributed by Peter L. Montgomery.
|
|
|
|
THIS IS AN INTERNAL FUNCTION WITH A MUTABLE INTERFACE. IT IS ONLY SAFE
|
|
TO REACH THIS FUNCTION THROUGH DOCUMENTED INTERFACES. IN FACT, IT IS
|
|
ALMOST GUARANTEED THAT THIS FUNCTION WILL CHANGE OR DISAPPEAR IN A FUTURE
|
|
GNU MP RELEASE.
|
|
|
|
|
|
Copyright 1992, 1994, 1996, 2000 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"
|
|
|
|
mp_limb_t
|
|
mpn_udiv_w_sdiv (rp, a1, a0, d)
|
|
mp_limb_t *rp, a1, a0, d;
|
|
{
|
|
mp_limb_t q, r;
|
|
mp_limb_t c0, c1, b1;
|
|
|
|
ASSERT (d != 0);
|
|
ASSERT (a1 < d);
|
|
|
|
if ((mp_limb_signed_t) d >= 0)
|
|
{
|
|
if (a1 < d - a1 - (a0 >> (BITS_PER_MP_LIMB - 1)))
|
|
{
|
|
/* dividend, divisor, and quotient are nonnegative */
|
|
sdiv_qrnnd (q, r, a1, a0, d);
|
|
}
|
|
else
|
|
{
|
|
/* Compute c1*2^32 + c0 = a1*2^32 + a0 - 2^31*d */
|
|
sub_ddmmss (c1, c0, a1, a0, d >> 1, d << (BITS_PER_MP_LIMB - 1));
|
|
/* Divide (c1*2^32 + c0) by d */
|
|
sdiv_qrnnd (q, r, c1, c0, d);
|
|
/* Add 2^31 to quotient */
|
|
q += (mp_limb_t) 1 << (BITS_PER_MP_LIMB - 1);
|
|
}
|
|
}
|
|
else
|
|
{
|
|
b1 = d >> 1; /* d/2, between 2^30 and 2^31 - 1 */
|
|
c1 = a1 >> 1; /* A/2 */
|
|
c0 = (a1 << (BITS_PER_MP_LIMB - 1)) + (a0 >> 1);
|
|
|
|
if (a1 < b1) /* A < 2^32*b1, so A/2 < 2^31*b1 */
|
|
{
|
|
sdiv_qrnnd (q, r, c1, c0, b1); /* (A/2) / (d/2) */
|
|
|
|
r = 2*r + (a0 & 1); /* Remainder from A/(2*b1) */
|
|
if ((d & 1) != 0)
|
|
{
|
|
if (r >= q)
|
|
r = r - q;
|
|
else if (q - r <= d)
|
|
{
|
|
r = r - q + d;
|
|
q--;
|
|
}
|
|
else
|
|
{
|
|
r = r - q + 2*d;
|
|
q -= 2;
|
|
}
|
|
}
|
|
}
|
|
else if (c1 < b1) /* So 2^31 <= (A/2)/b1 < 2^32 */
|
|
{
|
|
c1 = (b1 - 1) - c1;
|
|
c0 = ~c0; /* logical NOT */
|
|
|
|
sdiv_qrnnd (q, r, c1, c0, b1); /* (A/2) / (d/2) */
|
|
|
|
q = ~q; /* (A/2)/b1 */
|
|
r = (b1 - 1) - r;
|
|
|
|
r = 2*r + (a0 & 1); /* A/(2*b1) */
|
|
|
|
if ((d & 1) != 0)
|
|
{
|
|
if (r >= q)
|
|
r = r - q;
|
|
else if (q - r <= d)
|
|
{
|
|
r = r - q + d;
|
|
q--;
|
|
}
|
|
else
|
|
{
|
|
r = r - q + 2*d;
|
|
q -= 2;
|
|
}
|
|
}
|
|
}
|
|
else /* Implies c1 = b1 */
|
|
{ /* Hence a1 = d - 1 = 2*b1 - 1 */
|
|
if (a0 >= -d)
|
|
{
|
|
q = -1;
|
|
r = a0 + d;
|
|
}
|
|
else
|
|
{
|
|
q = -2;
|
|
r = a0 + 2*d;
|
|
}
|
|
}
|
|
}
|
|
|
|
*rp = r;
|
|
return q;
|
|
}
|