/*

** FAAD2 - Freeware Advanced Audio (AAC) Decoder including SBR decoding

** Copyright (C) 2003-2005 M. Bakker, Nero AG, http://www.nero.com

**

** This program 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.

**

** This program 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 this program; if not, write to the Free Software

** Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

**

** Any non-GPL usage of this software or parts of this software is strictly

** forbidden.

**

** The "appropriate copyright message" mentioned in section 2c of the GPLv2

** must read: "Code from FAAD2 is copyright (c) Nero AG, www.nero.com"

**

** Commercial non-GPL licensing of this software is possible.

** For more info contact Nero AG through Mpeg4AAClicense@nero.com.

**

** $Id: tns.c,v 1.40 2007/11/01 12:33:40 menno Exp $

**/

#include "common.h"

#include "structs.h"

#include "syntax.h"

#include "tns.h"

/* static function declarations */

/* returns exp */

static uint8_t tns_decode_coef(uint8_t order, uint8_t coef_res_bits,

                               uint8_t coef_compress, uint8_t *coef, real_t *a);

static void tns_ar_filter(real_t *spectrum, uint16_t size, int8_t inc, real_t *lpc,

                          uint8_t order, uint8_t exp);

static void tns_ma_filter(real_t *spectrum, uint16_t size, int8_t inc, real_t *lpc,

                          uint8_t order, uint8_t exp);

#ifdef _MSC_VER

#pragma warning(disable:4305)

#pragma warning(disable:4244)

#endif

static real_t tns_coef_0_3[] =

{

    COEF_CONST(0.0), COEF_CONST(0.4338837391), COEF_CONST(0.7818314825), COEF_CONST(0.9749279122),

    COEF_CONST(-0.9848077530), COEF_CONST(-0.8660254038), COEF_CONST(-0.6427876097), COEF_CONST(-0.3420201433),

    COEF_CONST(-0.4338837391), COEF_CONST(-0.7818314825), COEF_CONST(-0.9749279122), COEF_CONST(-0.9749279122),

    COEF_CONST(-0.9848077530), COEF_CONST(-0.8660254038), COEF_CONST(-0.6427876097), COEF_CONST(-0.3420201433)

};

static real_t tns_coef_0_4[] =

{

    COEF_CONST(0.0), COEF_CONST(0.2079116908), COEF_CONST(0.4067366431), COEF_CONST(0.5877852523),

    COEF_CONST(0.7431448255), COEF_CONST(0.8660254038), COEF_CONST(0.9510565163), COEF_CONST(0.9945218954),

    COEF_CONST(-0.9957341763), COEF_CONST(-0.9618256432), COEF_CONST(-0.8951632914), COEF_CONST(-0.7980172273),

    COEF_CONST(-0.6736956436), COEF_CONST(-0.5264321629), COEF_CONST(-0.3612416662), COEF_CONST(-0.1837495178)

};

static real_t tns_coef_1_3[] =

{

    COEF_CONST(0.0), COEF_CONST(0.4338837391), COEF_CONST(-0.6427876097), COEF_CONST(-0.3420201433),

    COEF_CONST(0.9749279122), COEF_CONST(0.7818314825), COEF_CONST(-0.6427876097), COEF_CONST(-0.3420201433),

    COEF_CONST(-0.4338837391), COEF_CONST(-0.7818314825), COEF_CONST(-0.6427876097), COEF_CONST(-0.3420201433),

    COEF_CONST(-0.7818314825), COEF_CONST(-0.4338837391), COEF_CONST(-0.6427876097), COEF_CONST(-0.3420201433)

};

static real_t tns_coef_1_4[] =

{

    COEF_CONST(0.0), COEF_CONST(0.2079116908), COEF_CONST(0.4067366431), COEF_CONST(0.5877852523),

    COEF_CONST(-0.6736956436), COEF_CONST(-0.5264321629), COEF_CONST(-0.3612416662), COEF_CONST(-0.1837495178),

    COEF_CONST(0.9945218954), COEF_CONST(0.9510565163), COEF_CONST(0.8660254038), COEF_CONST(0.7431448255),

    COEF_CONST(-0.6736956436), COEF_CONST(-0.5264321629), COEF_CONST(-0.3612416662), COEF_CONST(-0.1837495178)

};

static real_t* all_tns_coefs[] = {tns_coef_0_3, tns_coef_0_4, tns_coef_1_3, tns_coef_1_4};

/* TNS decoding for one channel and frame */

void tns_decode_frame(ic_stream *ics, tns_info *tns, uint8_t sr_index,

                      uint8_t object_type, real_t *spec, uint16_t frame_len)

{

    uint8_t w, f, tns_order;

    int8_t inc;

    int16_t size;

    uint16_t bottom, top, start, end;

    uint16_t nshort = frame_len/8;

    real_t lpc[TNS_MAX_ORDER+1];

    uint8_t exp;

    if (!ics->tns_data_present)

        return;

    for (w = 0; w < ics->num_windows; w++)

    {

        bottom = ics->num_swb;

        for (f = 0; f < tns->n_filt[w]; f++)

        {

            top = bottom;

            bottom = max(top - tns->length[w][f], 0);

            tns_order = min(tns->order[w][f], TNS_MAX_ORDER);

            if (!tns_order)

                continue;

            exp = tns_decode_coef(tns_order, tns->coef_res[w]+3,

                tns->coef_compress[w][f], tns->coef[w][f], lpc);

            start = min(bottom, max_tns_sfb(sr_index, object_type, (ics->window_sequence == EIGHT_SHORT_SEQUENCE)));

            start = min(start, ics->max_sfb);

            start = min(ics->swb_offset[start], ics->swb_offset_max);

            end = min(top, max_tns_sfb(sr_index, object_type, (ics->window_sequence == EIGHT_SHORT_SEQUENCE)));

            end = min(end, ics->max_sfb);

            end = min(ics->swb_offset[end], ics->swb_offset_max);

            size = end - start;

            if (size <= 0)

                continue;

            if (tns->direction[w][f])

            {

                inc = -1;

                start = end - 1;

            } else {

                inc = 1;

            }

            tns_ar_filter(&spec[(w*nshort)+start], size, inc, lpc, tns_order, exp);

        }

    }

}

/* TNS encoding for one channel and frame */

void tns_encode_frame(ic_stream *ics, tns_info *tns, uint8_t sr_index,

                      uint8_t object_type, real_t *spec, uint16_t frame_len)

{

    uint8_t w, f, tns_order;

    int8_t inc;

    int16_t size;

    uint16_t bottom, top, start, end;

    uint16_t nshort = frame_len/8;

    real_t lpc[TNS_MAX_ORDER+1];

    uint8_t exp;

    if (!ics->tns_data_present)

        return;

    for (w = 0; w < ics->num_windows; w++)

    {

        bottom = ics->num_swb;

        for (f = 0; f < tns->n_filt[w]; f++)

        {

            top = bottom;

            bottom = max(top - tns->length[w][f], 0);

            tns_order = min(tns->order[w][f], TNS_MAX_ORDER);

            if (!tns_order)

                continue;

            exp = tns_decode_coef(tns_order, tns->coef_res[w]+3,

                tns->coef_compress[w][f], tns->coef[w][f], lpc);

            start = min(bottom, max_tns_sfb(sr_index, object_type, (ics->window_sequence == EIGHT_SHORT_SEQUENCE)));

            start = min(start, ics->max_sfb);

            start = min(ics->swb_offset[start], ics->swb_offset_max);

            end = min(top, max_tns_sfb(sr_index, object_type, (ics->window_sequence == EIGHT_SHORT_SEQUENCE)));

            end = min(end, ics->max_sfb);

            end = min(ics->swb_offset[end], ics->swb_offset_max);

            size = end - start;

            if (size <= 0)

                continue;

            if (tns->direction[w][f])

            {

                inc = -1;

                start = end - 1;

            } else {

                inc = 1;

            }

            tns_ma_filter(&spec[(w*nshort)+start], size, inc, lpc, tns_order, exp);

        }

    }

}

/* Decoder transmitted coefficients for one TNS filter */

static uint8_t tns_decode_coef(uint8_t order, uint8_t coef_res_bits, uint8_t coef_compress,

                            uint8_t *coef, real_t *a)

{

    uint8_t i, m;

    real_t tmp2[TNS_MAX_ORDER+1], b[TNS_MAX_ORDER+1];

    uint8_t table_index = 2 * (coef_compress != 0) + (coef_res_bits != 3);

    real_t* tns_coef = all_tns_coefs[table_index];

    uint8_t exp = 0;

    /* Conversion to signed integer */

    for (i = 0; i < order; i++)

        tmp2[i] = tns_coef[coef[i]];

    /* Conversion to LPC coefficients */

    a[0] = COEF_CONST(1.0);

    for (m = 1; m <= order; m++)

    {

        a[m] = tmp2[m-1]; /* changed */

        for (i = 1; i < m; i++) /* loop only while i<m */

            b[i] = a[i] + MUL_C(a[m], a[m-i]);

        for (i = 1; i < m; i++) /* loop only while i<m */

            a[i] = b[i];

#ifdef FIXED_POINT

        a[m] >>= exp;

        /* OK not to check after the last iteration. */

        if (m < order)

        {

            real_t sum_abs = COEF_CONST(0.0);

            for (i = 1; i <= m; ++i)

            {

                sum_abs += (a[i] >= 0) ? a[i] : -a[i];

            }

            /* Next iteration would turn sum to 2*sum + 1; maximal "coef" is 7.999 */

            if (sum_abs >= COEF_CONST(3.5))

            {

                exp++;

                for (i = 1; i <= m; ++i)

                {

                    a[i] >>= 1;

                }

            }

        }

#endif

    }

    return exp;

}

static void tns_ar_filter(real_t *spectrum, uint16_t size, int8_t inc, real_t *lpc,

                          uint8_t order, uint8_t exp)

{

    /*

     - Simple all-pole filter of order "order" defined by

       y(n) = x(n) - lpc[1]*y(n-1) - ... - lpc[order]*y(n-order)

     - The state variables of the filter are initialized to zero every time

     - The output data is written over the input data ("in-place operation")

     - An input vector of "size" samples is processed and the index increment

       to the next data sample is given by "inc"

    */

    uint8_t j;

    uint16_t i;

    /* state is stored as a double ringbuffer */

    real_t state[2*TNS_MAX_ORDER] = {0};

    int8_t state_index = 0;

    int32_t mul = 1;

#ifdef FIXED_POINT

    if (exp >= 4)

        return;

    mul = 1 << exp;

#else

    (void)exp;

#endif

    for (i = 0; i < size; i++)

    {

        real_t y = REAL_CONST(0.0);

        for (j = 0; j < order; j++)

            y += MUL_C(state[state_index+j], lpc[j+1]);

        y = *spectrum - (y * mul);

        /* double ringbuffer state */

        state_index--;

        if (state_index < 0)

            state_index = order-1;

        state[state_index] = state[state_index + order] = y;

        *spectrum = y;

        spectrum += inc;

//#define TNS_PRINT

#ifdef TNS_PRINT

        //printf("%d\n", y);

        printf("0x%.8X\n", y);

#endif

    }

}

static void tns_ma_filter(real_t *spectrum, uint16_t size, int8_t inc, real_t *lpc,

                          uint8_t order, uint8_t exp)

{

    /*

     - Simple all-zero filter of order "order" defined by

       y(n) =  x(n) + a(2)*x(n-1) + ... + a(order+1)*x(n-order)

     - The state variables of the filter are initialized to zero every time

     - The output data is written over the input data ("in-place operation")

     - An input vector of "size" samples is processed and the index increment

       to the next data sample is given by "inc"

    */

    uint8_t j;

    uint16_t i;

    /* state is stored as a double ringbuffer */

    real_t state[2*TNS_MAX_ORDER] = {0};

    int8_t state_index = 0;

    int32_t mul = 1;

#ifdef FIXED_POINT

    if (exp >= 4)

        return;

    mul = 1 << exp;

#else

    (void)exp;

#endif

    for (i = 0; i < size; i++)

    {

        real_t y = REAL_CONST(0.0);

        for (j = 0; j < order; j++)

            y += MUL_C(state[state_index+j], lpc[j+1]);

        y = *spectrum + (y * mul);

        /* double ringbuffer state */

        state_index--;

        if (state_index < 0)

            state_index = order-1;

        state[state_index] = state[state_index + order] = *spectrum;

        *spectrum = y;

        spectrum += inc;

    }

}