pqc/external/flint-2.4.3/nmod_poly/div.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) 2010 Sebastian Pancratz
Copyright (C) 2011 William Hart
******************************************************************************/
#include <stdlib.h>
#include <gmp.h>
#include "flint.h"
#include "nmod_vec.h"
#include "nmod_poly.h"
void
_nmod_poly_div(mp_ptr Q, mp_srcptr A, slong lenA,
mp_srcptr B, slong lenB, nmod_t mod)
{
TMP_INIT;
if (lenB < 15)
{
mp_ptr W;
TMP_START;
W = TMP_ALLOC(NMOD_DIV_BC_ITCH(lenA, lenB, mod)*sizeof(mp_limb_t));
_nmod_poly_div_basecase(Q, W, A, lenA, B, lenB, mod);
TMP_END;
}
else if (lenB < 6000)
_nmod_poly_div_divconquer(Q, A, lenA, B, lenB, mod);
else
_nmod_poly_div_newton(Q, A, lenA, B, lenB, mod);
}
void
nmod_poly_div(nmod_poly_t Q,
const nmod_poly_t A, const nmod_poly_t B)
{
nmod_poly_t tQ;
mp_ptr q;
slong A_len, B_len;
B_len = B->length;
if (B_len == 0)
{
flint_printf("Exception (nmod_poly_divrem). Division by zero.\n");
abort();
}
A_len = A->length;
if (A_len < B_len)
{
nmod_poly_zero(Q);
return;
}
if (Q == A || Q == B)
{
nmod_poly_init2(tQ, A->mod.n, A_len - B_len + 1);
q = tQ->coeffs;
}
else
{
nmod_poly_fit_length(Q, A_len - B_len + 1);
q = Q->coeffs;
}
_nmod_poly_div(q, A->coeffs, A_len,
B->coeffs, B_len, A->mod);
if (Q == A || Q == B)
{
nmod_poly_swap(tQ, Q);
nmod_poly_clear(tQ);
}
Q->length = A_len - B_len + 1;
}