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

86 lines
2.5 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) 2012 Sebastian Pancratz
Copyright (C) 2013 Mike Hansen
******************************************************************************/
#include "fq_nmod.h"
void _fq_nmod_trace(fmpz_t rop2, const mp_limb_t *op, slong len,
const fq_nmod_ctx_t ctx)
{
const slong d = fq_nmod_ctx_degree(ctx);
ulong i, l;
mp_limb_t *t, rop;
t = _nmod_vec_init(d);
_nmod_vec_zero(t, d);
t[0] = n_mod2_preinv(d, ctx->mod.n, ctx->mod.ninv);
for (i = 1; i < d; i++)
{
for (l = ctx->len - 2; l >= 0 && ctx->j[l] >= d - (i - 1); l--)
{
t[i] = n_addmod(t[i],
n_mulmod2_preinv(t[ctx->j[l] + i - d], ctx->a[l], ctx->mod.n, ctx->mod.ninv),
ctx->mod.n);
}
if (l >= 0 && ctx->j[l] == d - i)
{
t[i] = n_addmod(t[i],
n_mulmod2_preinv(ctx->a[l], i, ctx->mod.n, ctx->mod.ninv),
ctx->mod.n);
}
t[i] = n_negmod(t[i], ctx->mod.n);
}
rop = WORD(0);
for (i = 0; i < d; i++)
{
rop = n_addmod(rop,
n_mulmod2_preinv(op[i], t[i], ctx->mod.n, ctx->mod.ninv),
ctx->mod.n);
}
_nmod_vec_clear(t);
fmpz_set_ui(rop2, rop);
}
void fq_nmod_trace(fmpz_t rop, const fq_nmod_t op, const fq_nmod_ctx_t ctx)
{
if (fq_nmod_is_zero(op, ctx))
{
fmpz_zero(rop);
return;
}
_fq_nmod_trace(rop, op->coeffs, op->length, ctx);
}