pqc/external/flint-2.4.3/qadic/exp.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) 2012 Sebastian Pancratz
******************************************************************************/
#include "fmpz_mod_poly.h"
#include "qadic.h"
void _qadic_exp(fmpz *rop, const fmpz *op, slong v, slong len,
const fmpz *a, const slong *j, slong lena,
const fmpz_t p, slong N, const fmpz_t pN)
{
if (N < (WORD(1) << 13) / (slong) fmpz_bits(p))
{
_qadic_exp_rectangular(rop, op, v, len, a, j, lena, p, N, pN);
}
else
{
const slong d = j[lena - 1];
_qadic_exp_balanced(rop, op, v, len, a, j, lena, p, N, pN);
_fmpz_vec_zero(rop + d, d - 1);
}
}
int qadic_exp(qadic_t rop, const qadic_t op, const qadic_ctx_t ctx)
{
const slong N = qadic_prec(rop);
const slong v = op->val;
const fmpz *p = (&ctx->pctx)->p;
if (padic_poly_is_zero(op))
{
padic_poly_one(rop);
return 1;
}
if ((*p == WORD(2) && v <= 1) || (v <= 0))
{
return 0;
}
else
{
if (v < N)
{
const slong d = qadic_ctx_degree(ctx);
fmpz *t;
fmpz_t pN;
int alloc;
alloc = _padic_ctx_pow_ui(pN, N, &ctx->pctx);
if (rop == op)
{
t = _fmpz_vec_init(2 * d - 1);
}
else
{
padic_poly_fit_length(rop, 2 * d - 1);
t = rop->coeffs;
}
_qadic_exp(t, op->coeffs, v, op->length,
ctx->a, ctx->j, ctx->len, p, N, pN);
rop->val = 0;
if (rop == op)
{
_fmpz_vec_clear(rop->coeffs, rop->alloc);
rop->coeffs = t;
rop->alloc = 2 * d - 1;
rop->length = d;
}
_padic_poly_set_length(rop, d);
_padic_poly_normalise(rop);
if (alloc)
fmpz_clear(pN);
}
else
{
padic_poly_one(rop);
}
return 1;
}
}