/*

** 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: ms.c,v 1.21 2007/11/01 12:33:32 menno Exp $

**/

#include "common.h"

#include "structs.h"

#include "syntax.h"

#include "ms.h"

#include "is.h"

#include "pns.h"

void ms_decode(ic_stream *ics, ic_stream *icsr, real_t *l_spec, real_t *r_spec,

               uint16_t frame_len)

{

    uint8_t g, b, sfb;

    uint8_t group = 0;

    uint16_t nshort = frame_len/8;

    uint16_t i, k;

    real_t tmp;

    if (ics->ms_mask_present >= 1)

    {

        for (g = 0; g < ics->num_window_groups; g++)

        {

            for (b = 0; b < ics->window_group_length[g]; b++)

            {

                for (sfb = 0; sfb < ics->max_sfb; sfb++)

                {

                    /* If intensity stereo coding or noise substitution is on

                       for a particular scalefactor band, no M/S stereo decoding

                       is carried out.

                     */

                    if ((ics->ms_used[g][sfb] || ics->ms_mask_present == 2) &&

                        !is_intensity(icsr, g, sfb) && !is_noise(ics, g, sfb))

                    {

                        for (i = ics->swb_offset[sfb]; i < min(ics->swb_offset[sfb+1], ics->swb_offset_max); i++)

                        {

                            k = (group*nshort) + i;

                            tmp = l_spec[k] - r_spec[k];

                            l_spec[k] = l_spec[k] + r_spec[k];

                            r_spec[k] = tmp;

                        }

                    }

                }

                group++;

            }

        }

    }

}