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

245 lines
6.0 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) 2012 Sebastian Pancratz
Copyright (C) 2013 Mike Hansen
******************************************************************************/
#ifdef T
#include "templates.h"
/*
Include routines for vectors over \code{fmpz_poly_struct},
for use in the classical multiplication routine in the
$X$-direction.
*/
static fmpz_poly_struct *
__vec_init(slong len)
{
slong i;
fmpz_poly_struct *v;
v = flint_malloc(len * sizeof(fmpz_poly_struct));
for (i = 0; i < len; i++)
fmpz_poly_init(v + i);
return v;
}
static fmpz_poly_struct *
__vec_init2(slong len, slong n)
{
slong i;
fmpz_poly_struct *v;
v = flint_malloc(len * sizeof(fmpz_poly_struct));
for (i = 0; i < len; i++)
fmpz_poly_init2(v + i, n);
return v;
}
static void
__vec_clear(fmpz_poly_struct * v, slong len)
{
slong i;
for (i = 0; i < len; i++)
fmpz_poly_clear(v + i);
flint_free(v);
}
static void
__scalar_addmul(fmpz_poly_struct * rop,
const fmpz_poly_struct * op, slong len, const fmpz_poly_t x)
{
slong i;
if (fmpz_poly_is_zero(x))
{
return;
}
else if (fmpz_poly_is_one(x))
{
for (i = 0; i < len; i++)
fmpz_poly_add(rop + i, rop + i, op + i);
}
else
{
fmpz_poly_t t;
fmpz_poly_init(t);
for (i = 0; i < len; i++)
{
fmpz_poly_mul(t, op + i, x);
fmpz_poly_add(rop + i, rop + i, t);
}
fmpz_poly_clear(t);
}
}
static void
__scalar_mul(fmpz_poly_struct * rop,
const fmpz_poly_struct * op, slong len, const fmpz_poly_t x)
{
slong i;
if (fmpz_poly_is_zero(x))
{
for (i = 0; i < len; i++)
fmpz_poly_zero(rop + i);
}
else if (fmpz_poly_is_one(x))
{
for (i = 0; i < len; i++)
fmpz_poly_set(rop + i, op + i);
}
else
{
for (i = 0; i < len; i++)
fmpz_poly_mul(rop + i, op + i, x);
}
}
static void
__sqr(fmpz_poly_struct * rop, fmpz_poly_struct * op, slong len)
{
if (len == 1)
{
fmpz_poly_sqr(rop, op);
}
else
{
slong i;
fmpz_poly_t t;
fmpz_poly_init(t);
__scalar_mul(rop, op, len, op);
__scalar_mul(rop + len, op + 1, len - 1, op + len - 1);
for (i = 1; i < len - 1; i++)
__scalar_addmul(rop + i + 1, op + 1, i - 1, op + i);
for (i = 1; i < 2 * len - 2; i++)
fmpz_poly_add(rop + i, rop + i, rop + i);
for (i = 1; i < len - 1; i++)
{
fmpz_poly_sqr(t, op + i);
fmpz_poly_add(rop + 2 * i, rop + 2 * i, t);
}
fmpz_poly_clear(t);
}
}
void
_TEMPLATE(T, poly_sqr_reorder) (TEMPLATE(T, struct) * rop,
const TEMPLATE(T, struct) * op, slong len,
const TEMPLATE(T, ctx_t) ctx)
{
const slong d = TEMPLATE(T, ctx_degree) (ctx);
fmpz_poly_struct *f, *g;
slong i, j, k, lenF;
f = __vec_init(2 * d - 1);
g = __vec_init2(d, len);
/* Convert (op, len) to (g, d) */
for (i = 0; i < len; i++)
for (j = 0; j < fmpz_poly_length(op + i); j++)
fmpz_set((g + j)->coeffs + i, (op + i)->coeffs + j);
for (j = 0; j < d; j++)
{
_fmpz_poly_set_length(g + j, len);
_fmpz_poly_normalise(g + j);
}
__sqr(f, g, d);
/* Normalise (f, len) */
lenF = 2 * d - 1;
while ((lenF) && fmpz_poly_is_zero(f + (lenF - 1)))
lenF--;
/* Reduce (f, j) using polynomial operations */
if (lenF > d)
{
for (i = lenF - 1; i >= d; i--)
{
for (k = ctx->len - 2; k >= 0; k--)
{
fmpz_poly_scalar_submul_fmpz(f + ctx->j[k] + i - d, f + i,
ctx->a + k);
}
fmpz_poly_zero(f + i);
}
}
for (j = 0; j < FLINT_MIN(d, lenF); j++)
fmpz_poly_scalar_mod_fmpz(f + j, f + j, TEMPLATE(T, ctx_prime) (ctx));
/* Convert (f, d) to (rop, 2 * len - 1) */
for (i = 0; i < 2 * len - 1; i++)
{
fmpz_poly_fit_length(rop + i, d);
_fmpz_vec_zero((rop + i)->coeffs, d);
}
for (j = 0; j < d; j++)
for (i = 0; i < fmpz_poly_length(f + j); i++)
fmpz_set((rop + i)->coeffs + j, (f + j)->coeffs + i);
for (i = 0; i < 2 * len - 1; i++)
{
_fmpz_poly_set_length(rop + i, d);
_fmpz_poly_normalise(rop + i);
}
__vec_clear(f, 2 * d - 1);
__vec_clear(g, d);
}
void
TEMPLATE(T, poly_sqr_reorder) (TEMPLATE(T, poly_t) rop,
const TEMPLATE(T, poly_t) op,
const TEMPLATE(T, ctx_t) ctx)
{
const slong len = 2 * op->length - 1;
if (op->length == 0)
{
TEMPLATE(T, poly_zero) (rop, ctx);
}
else
{
TEMPLATE(T, poly_fit_length) (rop, len, ctx);
_TEMPLATE(T, poly_sqr_reorder) (rop->coeffs, op->coeffs, op->length,
ctx);
_TEMPLATE(T, poly_set_length) (rop, len, ctx);
}
}
#endif