110 lines
3.3 KiB
C
110 lines
3.3 KiB
C
/*=============================================================================
|
|
|
|
This file is part of FLINT.
|
|
|
|
FLINT is free software; you can redistribute it and/or modify
|
|
it under the terms of the GNU General Public License as published by
|
|
the Free Software Foundation; either version 2 of the License, or
|
|
(at your option) any later version.
|
|
|
|
FLINT 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 General Public License for more details.
|
|
|
|
You should have received a copy of the GNU General Public License
|
|
along with FLINT; if not, write to the Free Software
|
|
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
|
|
|
|
=============================================================================*/
|
|
/******************************************************************************
|
|
|
|
Copyright (C) 2009 William Hart
|
|
|
|
******************************************************************************/
|
|
|
|
#include <gmp.h>
|
|
#include "flint.h"
|
|
#include "ulong_extras.h"
|
|
#include "fmpz.h"
|
|
|
|
void
|
|
fmpz_addmul_ui(fmpz_t f, const fmpz_t g, ulong x)
|
|
{
|
|
fmpz c1, r;
|
|
|
|
c1 = *g;
|
|
if ((x == 0) || (c1 == 0)) /* product is zero */
|
|
return;
|
|
|
|
r = *f;
|
|
if (r == 0)
|
|
{
|
|
fmpz_mul_ui(f, g, x); /* we are adding product to 0 */
|
|
return;
|
|
}
|
|
|
|
if (x == UWORD(1)) /* special case, adding g*1 to f */
|
|
{
|
|
fmpz_add(f, f, g);
|
|
return;
|
|
}
|
|
|
|
if (c1 == UWORD(1)) /* special case, adding 1*x to f */
|
|
{
|
|
fmpz_add_ui(f, f, x);
|
|
return;
|
|
}
|
|
|
|
if (!COEFF_IS_MPZ(c1)) /* c1 is small */
|
|
{
|
|
mp_limb_t prod[2];
|
|
ulong uc1 = FLINT_ABS(c1);
|
|
|
|
umul_ppmm(prod[1], prod[0], uc1, x); /* compute product */
|
|
|
|
if (prod[1] == 0) /* product fits in one limb */
|
|
{
|
|
if (c1 < WORD(0))
|
|
fmpz_sub_ui(f, f, prod[0]);
|
|
else
|
|
fmpz_add_ui(f, f, prod[0]);
|
|
return;
|
|
}
|
|
else if ((prod[1] == 1) && (!COEFF_IS_MPZ(r)) && ((r ^ c1) < WORD(0)))
|
|
{
|
|
/*
|
|
only chance at cancellation is if product is one bit past
|
|
a limb and res is small and opposite sign to this product
|
|
*/
|
|
ulong ur = FLINT_ABS(r);
|
|
if (ur > prod[0]) /* cancellation will occur */
|
|
{
|
|
fmpz_set_ui(f, prod[0] - ur);
|
|
if (r > WORD(0))
|
|
fmpz_neg(f, f);
|
|
return;
|
|
}
|
|
}
|
|
|
|
/*
|
|
in all remaining cases res is either big already,
|
|
or will be big in the end
|
|
*/
|
|
{
|
|
__mpz_struct * mpz_ptr = _fmpz_promote_val(f);
|
|
mpz_t temp; /* set up a temporary, cheap mpz_t to contain prod */
|
|
temp->_mp_d = prod;
|
|
temp->_mp_size = (c1 < WORD(0) ? -2 : 2);
|
|
mpz_add(mpz_ptr, mpz_ptr, temp);
|
|
_fmpz_demote_val(f); /* cancellation may have occurred */
|
|
}
|
|
}
|
|
else /* c1 is large */
|
|
{
|
|
__mpz_struct * mpz_ptr = _fmpz_promote_val(f);
|
|
flint_mpz_addmul_ui(mpz_ptr, COEFF_TO_PTR(c1), x);
|
|
_fmpz_demote_val(f); /* cancellation may have occurred */
|
|
}
|
|
}
|