/*

 * Copyright (c) 2008-2024 Stefan Krah. All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 *

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in the

 *    documentation and/or other materials provided with the distribution.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND

 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE

 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL

 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS

 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT

 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY

 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF

 * SUCH DAMAGE.

 */

#include "bits.h"

#include "constants.h"

#include "convolute.h"

#include "fnt.h"

#include "fourstep.h"

#include "mpdecimal.h"

#include "numbertheory.h"

#include "sixstep.h"

#include "umodarith.h"

/*

 * Bignum: Fast convolution using the Number Theoretic Transform. Used for

 *         the multiplication of very large coefficients.

 */

/* Convolute the data in c1 and c2. Result is in c1. */

int

fnt_convolute(mpd_uint_t *c1, mpd_uint_t *c2, mpd_size_t n, int modnum)

{

    int (*fnt)(mpd_uint_t *, mpd_size_t, int);

    int (*inv_fnt)(mpd_uint_t *, mpd_size_t, int);

#ifdef PPRO

    double dmod;

    uint32_t dinvmod[3];

#endif

    mpd_uint_t n_inv, umod;

    mpd_size_t i;

    SETMODULUS(modnum);

    n_inv = POWMOD(n, (umod-2));

    if (ispower2(n)) {

        if (n > SIX_STEP_THRESHOLD) {

            fnt = six_step_fnt;

            inv_fnt = inv_six_step_fnt;

        }

        else {

            fnt = std_fnt;

            inv_fnt = std_inv_fnt;

        }

    }

    else {

        fnt = four_step_fnt;

        inv_fnt = inv_four_step_fnt;

    }

    if (!fnt(c1, n, modnum)) {

        return 0;

    }

    if (!fnt(c2, n, modnum)) {

        return 0;

    }

    for (i = 0; i < n-1; i += 2) {

        mpd_uint_t x0 = c1[i];

        mpd_uint_t y0 = c2[i];

        mpd_uint_t x1 = c1[i+1];

        mpd_uint_t y1 = c2[i+1];

        MULMOD2(&x0, y0, &x1, y1);

        c1[i] = x0;

        c1[i+1] = x1;

    }

    if (!inv_fnt(c1, n, modnum)) {

        return 0;

    }

    for (i = 0; i < n-3; i += 4) {

        mpd_uint_t x0 = c1[i];

        mpd_uint_t x1 = c1[i+1];

        mpd_uint_t x2 = c1[i+2];

        mpd_uint_t x3 = c1[i+3];

        MULMOD2C(&x0, &x1, n_inv);

        MULMOD2C(&x2, &x3, n_inv);

        c1[i] = x0;

        c1[i+1] = x1;

        c1[i+2] = x2;

        c1[i+3] = x3;

    }

    return 1;

}

/* Autoconvolute the data in c1. Result is in c1. */

int

fnt_autoconvolute(mpd_uint_t *c1, mpd_size_t n, int modnum)

{

    int (*fnt)(mpd_uint_t *, mpd_size_t, int);

    int (*inv_fnt)(mpd_uint_t *, mpd_size_t, int);

#ifdef PPRO

    double dmod;

    uint32_t dinvmod[3];

#endif

    mpd_uint_t n_inv, umod;

    mpd_size_t i;

    SETMODULUS(modnum);

    n_inv = POWMOD(n, (umod-2));

    if (ispower2(n)) {

        if (n > SIX_STEP_THRESHOLD) {

            fnt = six_step_fnt;

            inv_fnt = inv_six_step_fnt;

        }

        else {

            fnt = std_fnt;

            inv_fnt = std_inv_fnt;

        }

    }

    else {

        fnt = four_step_fnt;

        inv_fnt = inv_four_step_fnt;

    }

    if (!fnt(c1, n, modnum)) {

        return 0;

    }

    for (i = 0; i < n-1; i += 2) {

        mpd_uint_t x0 = c1[i];

        mpd_uint_t x1 = c1[i+1];

        MULMOD2(&x0, x0, &x1, x1);

        c1[i] = x0;

        c1[i+1] = x1;

    }

    if (!inv_fnt(c1, n, modnum)) {

        return 0;

    }

    for (i = 0; i < n-3; i += 4) {

        mpd_uint_t x0 = c1[i];

        mpd_uint_t x1 = c1[i+1];

        mpd_uint_t x2 = c1[i+2];

        mpd_uint_t x3 = c1[i+3];

        MULMOD2C(&x0, &x1, n_inv);

        MULMOD2C(&x2, &x3, n_inv);

        c1[i] = x0;

        c1[i+1] = x1;

        c1[i+2] = x2;

        c1[i+3] = x3;

    }

    return 1;

}