pqc/external/flint-2.4.3/fmpz_mod_poly/divrem_f.c
2014-05-24 23:16:06 +02:00

121 lines
3.0 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) 2011 Sebastian Pancratz
******************************************************************************/
#include <stdlib.h>
#include "fmpz_vec.h"
#include "fmpz_mod_poly.h"
void _fmpz_mod_poly_divrem_f(fmpz_t f, fmpz *Q, fmpz *R,
const fmpz *A, slong lenA,
const fmpz *B, slong lenB, const fmpz_t p)
{
fmpz_t invB;
fmpz_init(invB);
fmpz_gcdinv(f, invB, B + lenB - 1, p);
if (fmpz_is_one(f))
{
_fmpz_mod_poly_divrem(Q, R, A, lenA, B, lenB, invB, p);
}
fmpz_clear(invB);
}
void fmpz_mod_poly_divrem_f(fmpz_t f, fmpz_mod_poly_t Q, fmpz_mod_poly_t R,
const fmpz_mod_poly_t A, const fmpz_mod_poly_t B)
{
const slong lenA = A->length;
const slong lenB = B->length;
const slong lenQ = lenA - lenB + 1;
fmpz *q, *r;
fmpz_t invB;
fmpz_init(invB);
fmpz_gcdinv(f, invB, fmpz_poly_lead(B), &(B->p));
if (!fmpz_is_one(f))
{
fmpz_clear(invB);
return;
}
if (lenA < lenB)
{
fmpz_mod_poly_set(R, A);
fmpz_mod_poly_zero(Q);
fmpz_clear(invB);
return;
}
if (Q == A || Q == B)
{
q = _fmpz_vec_init(lenQ);
}
else
{
fmpz_mod_poly_fit_length(Q, lenQ);
q = Q->coeffs;
}
if (R == A || R == B)
{
r = _fmpz_vec_init(lenA);
}
else
{
fmpz_mod_poly_fit_length(R, lenA);
r = R->coeffs;
}
_fmpz_mod_poly_divrem_divconquer(q, r, A->coeffs, lenA,
B->coeffs, lenB, invB, &(B->p));
if (Q == A || Q == B)
{
_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)
{
_fmpz_vec_clear(R->coeffs, R->alloc);
R->coeffs = r;
R->alloc = lenA;
R->length = lenA;
}
_fmpz_mod_poly_set_length(R, lenB - 1);
_fmpz_mod_poly_normalise(R);
fmpz_clear(invB);
}