mpir/mpn/generic/addsub_n.c

94 lines
2.0 KiB
C

/* Copyright 2012 The Code cavern
This file is part of the MPIR Library.
The MPIR 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 MPIR 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 MPIR 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"
/* t = x + y - z */
int mpn_addsub_n(mp_ptr t, mp_srcptr x, mp_srcptr y, mp_srcptr z, mp_size_t n)
{
mp_limb_t ret;
ASSERT(n > 0);
ASSERT_MPN(x, n);
ASSERT_MPN(y, n);
ASSERT_MPN(z, n);
ASSERT(MPN_SAME_OR_SEPARATE_P(t, x, n));
ASSERT(MPN_SAME_OR_SEPARATE_P(t, y, n));
ASSERT(MPN_SAME_OR_SEPARATE_P(t, z, n));
if (t == x && t == y && t == z)
return 0;
if (t == x && t == y)
{
ret = mpn_add_n(t, x, y, n);
ret -= mpn_sub_n(t, t, z, n);
return ret;
}
if (t == x && t == z)
{
ret = -mpn_sub_n(t, x, z, n);
ret += mpn_add_n(t, t, y, n);
return ret;
}
if (t == y && t == z)
{
ret = -mpn_sub_n(t, y, z, n);
ret += mpn_add_n(t, t, x, n);
return ret;
}
if (t == x)
{
ret = mpn_add_n(t, x, y, n);
ret -= mpn_sub_n(t, t, z, n);
return ret;
}
if (t == y)
{
ret = mpn_add_n(t, y, x, n);
ret -= mpn_sub_n(t, t, z, n);
return ret;
}
if (t == z)
{
ret = -mpn_sub_n(t, x, z, n);
ret += mpn_add_n(t, t, y, n);
return ret;
}
ret = mpn_add_n(t, x, y, n);
ret -= mpn_sub_n(t, t, z, n);
return ret;
}