pqc/external/flint-2.4.3/fmpz_mod_poly/divrem_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) 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_divrem_newton_n_preinv (fmpz* Q, fmpz* R, 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_mod_poly_div_newton_n_preinv(Q, A, lenA, B, lenB, Binv, lenBinv, mod);
if (lenB > 1)
{
if (lenQ >= lenB - 1)
_fmpz_mod_poly_mullow(R, Q, lenQ, B, lenB - 1, mod, lenB - 1);
else
_fmpz_mod_poly_mullow(R, B, lenB - 1, Q, lenQ, mod, lenB - 1);
_fmpz_vec_sub(R, A, R, lenB - 1);
_fmpz_vec_scalar_mod_fmpz(R, R, lenB - 1, mod);
}
}
void fmpz_mod_poly_divrem_newton_n_preinv(fmpz_mod_poly_t Q, fmpz_mod_poly_t R,
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, lenBinv= Binv->length,
lenQ = lenA - lenB + 1;
fmpz* q, * r;
if (lenB == 0)
{
flint_printf("Exception (fmpz_mod_poly_divrem_newton_n_preinv)."
" Division by zero.\n");
abort();
}
if (lenA < lenB)
{
fmpz_mod_poly_set(R, A);
fmpz_mod_poly_zero(Q);
return;
}
if (lenA > 2 * lenB - 2)
{
flint_printf ("Exception (fmpz_mod_poly_divrem_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;
}
if (R == A || R == B || R == Binv)
{
r = _fmpz_vec_init(lenB - 1);
}
else
{
fmpz_mod_poly_fit_length(R, lenB - 1);
r = R->coeffs;
}
_fmpz_mod_poly_divrem_newton_n_preinv (q, r, 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);
}
if (R == A || R == B || R == Binv)
{
_fmpz_vec_clear(R->coeffs, R->alloc);
R->coeffs = r;
R->alloc = lenB - 1;
R->length = lenB - 1;
}
else
{
_fmpz_mod_poly_set_length(R, lenB - 1);
}
_fmpz_mod_poly_normalise(R);
}