/*****************************************************************************
 * aout_spdif.c: AC3 passthrough output
 *****************************************************************************
 * Copyright (C) 2001 VideoLAN
 * $Id: aout_spdif.c,v 1.24 2002/02/27 22:57:10 sam Exp $
 *
 * Authors: Michel Kaempf <maxx@via.ecp.fr>
 *          Stéphane Borel <stef@via.ecp.fr>
 *
 * 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, USA.
 *****************************************************************************/

/*****************************************************************************
 * Preamble
 *****************************************************************************/
#include <stdio.h>                                           /* "intf_msg.h" */
#include <stdlib.h>                            /* calloc(), malloc(), free() */
#include <string.h>                                              /* memset() */

#include <videolan/vlc.h>

#include "audio_output.h"
#include "aout_spdif.h"

/*****************************************************************************
 * aout_SpdifThread: audio output thread that sends raw spdif data
 *                   to an external decoder
 *****************************************************************************
 * This output thread is quite specific as it can only handle one fifo now.
 *
 * Note: spdif can demux up to 8 ac3 streams, and can even take
 * care of time stamps (cf ac3 spec) but I'm not sure all decoders
 * implement it.
 *****************************************************************************/
void aout_SpdifThread( aout_thread_t * p_aout )
{
    int         i_fifo;
    mtime_t     m_frame_time = 0;
    mtime_t     m_play;
    mtime_t     m_old = 0;

    while( !p_aout->b_die )
    {
        for( i_fifo = 0 ; i_fifo < AOUT_MAX_FIFOS ; i_fifo++ )
        {
            /* The loop reads each fifo so that we can change the stream
             * on the fly but mulitplexing is not handled yet so
             * the sound will be broken if more than one fifo has data */ 
            /* TODO: write the muliplexer :) */
            if( p_aout->fifo[i_fifo].i_format == AOUT_FIFO_SPDIF )
            {
                vlc_mutex_lock( &p_aout->fifo[i_fifo].data_lock );
                if( p_aout->fifo[i_fifo].b_die )
                {
                    vlc_mutex_unlock( &p_aout->fifo[i_fifo].data_lock );

                    vlc_mutex_lock( &p_aout->fifos_lock );
                    aout_FreeFifo( &p_aout->fifo[i_fifo] );
                    vlc_mutex_unlock( &p_aout->fifos_lock );
                }
                else if( !AOUT_FIFO_ISEMPTY( p_aout->fifo[i_fifo] ) )
                {
                    /* Copy data from fifo to buffer to release the
                     * lock earlier */
                    FAST_MEMCPY( p_aout->buffer,
                                 (byte_t *)p_aout->fifo[i_fifo].buffer
                                         + p_aout->fifo[i_fifo].i_start_frame
                                         * SPDIF_FRAME_SIZE,
                                 SPDIF_FRAME_SIZE );

                    m_play = p_aout->fifo[i_fifo].date[p_aout->fifo[i_fifo].
                                 i_start_frame];

                    p_aout->fifo[i_fifo].i_start_frame =
                        (p_aout->fifo[i_fifo].i_start_frame + 1 )
                        & AOUT_FIFO_SIZE;

                    /* Compute the theorical duration of an ac3 frame */
                    m_frame_time = 1000000 * AC3_FRAME_SIZE
                                           / p_aout->fifo[i_fifo].i_rate;

                    vlc_mutex_unlock( &p_aout->fifo[i_fifo].data_lock );

                    /* Play spdif frame to the external decoder 
                     * the kernel driver will sleep until the
                     * dsp buffer is empty enough to accept the data */
                    if( m_play > ( mdate() - m_frame_time ) )
                    {
                        /* check continuity */
                        if( (m_play - m_old) != m_frame_time )
                        {
                            mwait( m_play - m_frame_time );
                        }
                        else
                        {
                            mwait( m_play - 2 * m_frame_time );
                        }
                        m_old = m_play;

                        p_aout->pf_play( p_aout, (byte_t *)p_aout->buffer,
                                         SPDIF_FRAME_SIZE );
                    }
                }
                else
                {
                    vlc_mutex_unlock( &p_aout->fifo[i_fifo].data_lock );
                    msleep( m_frame_time );
                    intf_WarnMsg( 3, "aout warning: empty spdif fifo" );
                }
            }
        }
    }

    vlc_mutex_lock( &p_aout->fifos_lock );
    for ( i_fifo = 0; i_fifo < AOUT_MAX_FIFOS; i_fifo++ )
    {
        aout_FreeFifo( &p_aout->fifo[i_fifo] );
    }
    vlc_mutex_unlock( &p_aout->fifos_lock );

    return;
}