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

54 lines
1.6 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) 2013 Mike Hansen
******************************************************************************/
#include "fq_zech.h"
void
fq_zech_frobenius(fq_zech_t rop, const fq_zech_t op, slong e,
const fq_zech_ctx_t ctx)
{
double qm1_inv;
slong d = fq_zech_ctx_degree(ctx);
e = e % d;
if (e < 0)
e += d;
if (fq_zech_is_zero(op, ctx))
{
fq_zech_zero(rop, ctx);
}
else if (e == 0)
{
fq_zech_set(rop, op, ctx);
}
else
{
qm1_inv = n_precompute_inverse(ctx->qm1);
e = n_powmod(ctx->p, e, ctx->qm1);
rop->value = n_mulmod_precomp(op->value, e, ctx->qm1, qm1_inv);
}
}