/*

** 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: lt_predict.c,v 1.27 2007/11/01 12:33:31 menno Exp $

**/

#include "common.h"

#include "structs.h"

#ifdef LTP_DEC

#include <stdlib.h>

#include "syntax.h"

#include "lt_predict.h"

#include "filtbank.h"

#include "tns.h"

/* static function declarations */

static int16_t real_to_int16(real_t sig_in);

/* check if the object type is an object type that can have LTP */

uint8_t is_ltp_ot(uint8_t object_type)

{

#ifdef LTP_DEC

    if ((object_type == LTP)

#ifdef ERROR_RESILIENCE

        || (object_type == ER_LTP)

#endif

#ifdef LD_DEC

        || (object_type == LD)

#endif

        )

    {

        return 1;

    }

#endif

    return 0;

}

ALIGN static const real_t codebook[8] =

{

    REAL_CONST(0.570829),

    REAL_CONST(0.696616),

    REAL_CONST(0.813004),

    REAL_CONST(0.911304),

    REAL_CONST(0.984900),

    REAL_CONST(1.067894),

    REAL_CONST(1.194601),

    REAL_CONST(1.369533)

};

void lt_prediction(ic_stream *ics, ltp_info *ltp, real_t *spec,

                   int16_t *lt_pred_stat, fb_info *fb, uint8_t win_shape,

                   uint8_t win_shape_prev, uint8_t sr_index,

                   uint8_t object_type, uint16_t frame_len)

{

    uint8_t sfb;

    uint16_t bin, i, num_samples;

    ALIGN real_t x_est[2048];

    ALIGN real_t X_est[2048];

    if (ics->window_sequence != EIGHT_SHORT_SEQUENCE)

    {

        if (ltp->data_present)

        {

            num_samples = frame_len << 1;

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

            {

                /* The extra lookback M (N/2 for LD, 0 for LTP) is handled

                   in the buffer updating */

#if 0

                x_est[i] = MUL_R_C(lt_pred_stat[num_samples + i - ltp->lag],

                    codebook[ltp->coef]);

#else

                /* lt_pred_stat is a 16 bit int, multiplied with the fixed point real

                   this gives a real for x_est

                */

                x_est[i] = (real_t)lt_pred_stat[num_samples + i - ltp->lag] * codebook[ltp->coef];

#endif

            }

            filter_bank_ltp(fb, ics->window_sequence, win_shape, win_shape_prev,

                x_est, X_est, object_type, frame_len);

            tns_encode_frame(ics, &(ics->tns), sr_index, object_type, X_est,

                frame_len);

            for (sfb = 0; sfb < ltp->last_band; sfb++)

            {

                if (ltp->long_used[sfb])

                {

                    uint16_t low  = ics->swb_offset[sfb];

                    uint16_t high = min(ics->swb_offset[sfb+1], ics->swb_offset_max);

                    for (bin = low; bin < high; bin++)

                    {

                        spec[bin] += X_est[bin];

                    }

                }

            }

        }

    }

}

#ifdef FIXED_POINT

static INLINE int16_t real_to_int16(real_t sig_in)

{

    if (sig_in >= 0)

    {

        sig_in += (1 << (REAL_BITS-1));

        if (sig_in >= REAL_CONST(32768))

            return 32767;

    } else {

        sig_in += -(1 << (REAL_BITS-1));

        if (sig_in <= REAL_CONST(-32768))

            return -32768;

    }

    return (int16_t)(sig_in >> REAL_BITS);

}

#else

static INLINE int16_t real_to_int16(real_t sig_in)

{

    if (sig_in >= 0)

    {

#ifndef HAS_LRINTF

        sig_in += 0.5f;

#endif

        if (sig_in >= 32768.0f)

            return 32767;

    } else {

#ifndef HAS_LRINTF

        sig_in += -0.5f;

#endif

        if (sig_in <= -32768.0f)

            return -32768;

    }

    return (int16_t)lrintf(sig_in);

}

#endif

void lt_update_state(int16_t *lt_pred_stat, real_t *time, real_t *overlap,

                     uint16_t frame_len, uint8_t object_type)

{

    uint16_t i;

    /*

     * The reference point for index i and the content of the buffer

     * lt_pred_stat are arranged so that lt_pred_stat(0 ... N/2 - 1) contains the

     * last aliased half window from the IMDCT, and lt_pred_stat(N/2 ... N-1)

     * is always all zeros. The rest of lt_pred_stat (i<0) contains the previous

     * fully reconstructed time domain samples, i.e., output of the decoder.

     *

     * These values are shifted up by N*2 to avoid (i<0)

     *

     * For the LD object type an extra 512 samples lookback is accomodated here.

     */

#ifdef LD_DEC

    if (object_type == LD)

    {

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

        {

            lt_pred_stat[i]  /* extra 512 */  = lt_pred_stat[i + frame_len];

            lt_pred_stat[frame_len + i]       = lt_pred_stat[i + (frame_len * 2)];

            lt_pred_stat[(frame_len * 2) + i] = real_to_int16(time[i]);

            lt_pred_stat[(frame_len * 3) + i] = real_to_int16(overlap[i]);

        }

    } else {

#endif

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

        {

            lt_pred_stat[i]                   = lt_pred_stat[i + frame_len];

            lt_pred_stat[frame_len + i]       = real_to_int16(time[i]);

            lt_pred_stat[(frame_len * 2) + i] = real_to_int16(overlap[i]);

#if 0 /* set to zero once upon initialisation */

            lt_pred_stat[(frame_len * 3) + i] = 0;

#endif

        }

#ifdef LD_DEC

    }

#endif

}

#endif