pqc/external/flint-2.4.3/fmpz_mod_poly/div_newton_n_preinv.c

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2014-05-18 22:03:37 +00:00
/*=============================================================================
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) 2011, 2010 Sebastian Pancratz
Copyright (C) 2008, 2009 William Hart
Copyright (C) 2013 Martin Lee
******************************************************************************/
#undef ulong
#define ulong ulongxx/* interferes with system includes */
#include <stdlib.h>
#undef ulong
#include <gmp.h>
#define ulong mp_limb_t
#include "fmpz_vec.h"
#include "fmpz_mod_poly.h"
void _fmpz_mod_poly_div_newton_n_preinv (fmpz* Q, const fmpz* A, slong lenA,
const fmpz* B, slong lenB, const fmpz* Binv,
slong lenBinv, const fmpz_t mod)
{
const slong lenQ = lenA - lenB + 1;
fmpz * Arev;
Arev = _fmpz_vec_init(lenQ);
_fmpz_poly_reverse(Arev, A + (lenA - lenQ), lenQ, lenQ);
_fmpz_mod_poly_mullow(Q, Arev, lenQ, Binv, FLINT_MIN(lenQ, lenBinv), mod,
lenQ);
_fmpz_poly_reverse(Q, Q, lenQ, lenQ);
_fmpz_vec_clear(Arev, lenQ);
}
void fmpz_mod_poly_div_newton_n_preinv(fmpz_mod_poly_t Q,
const fmpz_mod_poly_t A, const fmpz_mod_poly_t B,
const fmpz_mod_poly_t Binv)
{
const slong lenA = A->length, lenB = B->length, lenQ = lenA - lenB + 1,
lenBinv = Binv->length;
fmpz *q;
if (lenB == 0)
{
flint_printf("Exception (fmpz_mod_poly_div_newton_n_preinv). Division by zero.\n");
abort();
}
if (lenA < lenB)
{
fmpz_mod_poly_zero(Q);
return;
}
if (lenA > 2 * lenB - 2)
{
flint_printf ("Exception (fmpz_mod_poly_div_newton_n_preinv).\n");
}
if (Q == A || Q == B || Q == Binv)
{
q = _fmpz_vec_init(lenQ);
}
else
{
fmpz_mod_poly_fit_length(Q, lenQ);
q = Q->coeffs;
}
_fmpz_mod_poly_div_newton_n_preinv (q, A->coeffs, lenA, B->coeffs, lenB,
Binv->coeffs, lenBinv, &(B->p));
if (Q == A || Q == B || Q == Binv)
{
_fmpz_vec_clear(Q->coeffs, Q->alloc);
Q->coeffs = q;
Q->alloc = lenQ;
Q->length = lenQ;
}
else
{
_fmpz_mod_poly_set_length(Q, lenQ);
}
}