/* Copyright (c) 2011 Xiph.Org Foundation
   Written by Jean-Marc Valin */
/*
   Redistribution and use in source and binary forms, with or without
   modification, are permitted provided that the following conditions
   are met:

   - Redistributions of source code must retain the above copyright
   notice, this list of conditions and the following disclaimer.

   - 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.

   - Neither the name of Internet Society, IETF or IETF Trust, nor the
   names of specific contributors, may be used to endorse or promote
   products derived from this software without specific prior written
   permission.

   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT OWNER
   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.
*/

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include "opus_multistream.h"
#include "opus.h"
#include "opus_private.h"
#include "stack_alloc.h"
#include <stdarg.h>
#include "float_cast.h"
#include "os_support.h"

typedef struct ChannelLayout {
   int nb_channels;
   int nb_streams;
   int nb_coupled_streams;
   unsigned char mapping[256];
} ChannelLayout;

struct OpusMSEncoder {
   ChannelLayout layout;
   int bitrate;
   /* Encoder states go here */
};

struct OpusMSDecoder {
   ChannelLayout layout;
   /* Decoder states go here */
};


#ifdef FIXED_POINT
#define opus_encode_native opus_encode
#else
#define opus_encode_native opus_encode_float
#endif

static int validate_layout(const ChannelLayout *layout)
{
   int i, max_channel;

   max_channel = layout->nb_streams+layout->nb_coupled_streams;
   if (max_channel>255)
      return 0;
   for (i=0;i<layout->nb_channels;i++)
   {
      if (layout->mapping[i] >= max_channel && layout->mapping[i] != 255)
         return 0;
   }
   return 1;
}


static int get_left_channel(const ChannelLayout *layout, int stream_id, int prev)
{
   int i;
   i = (prev<0) ? 0 : prev+1;
   for (;i<layout->nb_channels;i++)
   {
      if (layout->mapping[i]==stream_id*2)
         return i;
   }
   return -1;
}

static int get_right_channel(const ChannelLayout *layout, int stream_id, int prev)
{
   int i;
   i = (prev<0) ? 0 : prev+1;
   for (;i<layout->nb_channels;i++)
   {
      if (layout->mapping[i]==stream_id*2+1)
         return i;
   }
   return -1;
}

static int get_mono_channel(const ChannelLayout *layout, int stream_id, int prev)
{
   int i;
   i = (prev<0) ? 0 : prev+1;
   for (;i<layout->nb_channels;i++)
   {
      if (layout->mapping[i]==stream_id+layout->nb_coupled_streams)
         return i;
   }
   return -1;
}

static int validate_encoder_layout(const ChannelLayout *layout)
{
   int s;
   for (s=0;s<layout->nb_streams;s++)
   {
      if (s < layout->nb_coupled_streams)
      {
         if (get_left_channel(layout, s, -1)==-1)
            return 0;
         if (get_right_channel(layout, s, -1)==-1)
            return 0;
      } else {
         if (get_mono_channel(layout, s, -1)==-1)
            return 0;
      }
   }
   return 1;
}

opus_int32 opus_multistream_encoder_get_size(int nb_streams, int nb_coupled_streams)
{
   int coupled_size;
   int mono_size;

   if(nb_streams<1||nb_coupled_streams>nb_streams||nb_coupled_streams<0)return 0;
   coupled_size = opus_encoder_get_size(2);
   mono_size = opus_encoder_get_size(1);
   return align(sizeof(OpusMSEncoder))
        + nb_coupled_streams * align(coupled_size)
        + (nb_streams-nb_coupled_streams) * align(mono_size);
}



int opus_multistream_encoder_init(
      OpusMSEncoder *st,
      opus_int32 Fs,
      int channels,
      int streams,
      int coupled_streams,
      unsigned char *mapping,
      int application
)
{
   int coupled_size;
   int mono_size;
   int i;
   char *ptr;

   st->layout.nb_channels = channels;
   st->layout.nb_streams = streams;
   st->layout.nb_coupled_streams = coupled_streams;

   for (i=0;i<st->layout.nb_channels;i++)
      st->layout.mapping[i] = mapping[i];
   if (!validate_layout(&st->layout) || !validate_encoder_layout(&st->layout))
      return OPUS_BAD_ARG;
   ptr = (char*)st + align(sizeof(OpusMSEncoder));
   coupled_size = opus_encoder_get_size(2);
   mono_size = opus_encoder_get_size(1);

   for (i=0;i<st->layout.nb_coupled_streams;i++)
   {
      opus_encoder_init((OpusEncoder*)ptr, Fs, 2, application);
      ptr += align(coupled_size);
   }
   for (;i<st->layout.nb_streams;i++)
   {
      opus_encoder_init((OpusEncoder*)ptr, Fs, 1, application);
      ptr += align(mono_size);
   }
   return OPUS_OK;
}

OpusMSEncoder *opus_multistream_encoder_create(
      opus_int32 Fs,
      int channels,
      int streams,
      int coupled_streams,
      unsigned char *mapping,
      int application,
      int *error
)
{
   int ret;
   OpusMSEncoder *st = (OpusMSEncoder *)opus_alloc(opus_multistream_encoder_get_size(streams, coupled_streams));
   if (st==NULL)
   {
      if (error)
         *error = OPUS_ALLOC_FAIL;
      return NULL;
   }
   ret = opus_multistream_encoder_init(st, Fs, channels, streams, coupled_streams, mapping, application);
   if (ret != OPUS_OK)
   {
      opus_free(st);
      st = NULL;
   }
   if (error)
      *error = ret;
   return st;
}


#ifdef FIXED_POINT
int opus_multistream_encode(
#else
int opus_multistream_encode_float(
#endif
    OpusMSEncoder *st,
    const opus_val16 *pcm,
    int frame_size,
    unsigned char *data,
    int max_data_bytes
)
{
   int coupled_size;
   int mono_size;
   int s, i;
   char *ptr;
   int tot_size;
   VARDECL(opus_val16, buf);
   /* Max size in case the encoder decides to return three frames */
   unsigned char tmp_data[3*1275+7];
   OpusRepacketizer rp;
   ALLOC_STACK;

   ALLOC(buf, 2*frame_size, opus_val16);
   ptr = (char*)st + align(sizeof(OpusMSEncoder));
   coupled_size = opus_encoder_get_size(2);
   mono_size = opus_encoder_get_size(1);

   if (max_data_bytes < 2*st->layout.nb_streams-1)
   {
      RESTORE_STACK;
      return OPUS_BUFFER_TOO_SMALL;
   }
   /* Counting ToC */
   tot_size = 0;
   for (s=0;s<st->layout.nb_streams;s++)
   {
      OpusEncoder *enc;
      int len;
      int curr_max;

      opus_repacketizer_init(&rp);
      enc = (OpusEncoder*)ptr;
      if (s < st->layout.nb_coupled_streams)
      {
         int left, right;
         left = get_left_channel(&st->layout, s, -1);
         right = get_right_channel(&st->layout, s, -1);
         for (i=0;i<frame_size;i++)
         {
            buf[2*i] = pcm[st->layout.nb_channels*i+left];
            buf[2*i+1] = pcm[st->layout.nb_channels*i+right];
         }
         ptr += align(coupled_size);
      } else {
         int chan = get_mono_channel(&st->layout, s, -1);
         for (i=0;i<frame_size;i++)
            buf[i] = pcm[st->layout.nb_channels*i+chan];
         ptr += align(mono_size);
      }
      /* number of bytes left (+Toc) */
      curr_max = max_data_bytes - tot_size;
      /* Reserve one byte for the last stream and 2 for the others */
      curr_max -= 2*(st->layout.nb_streams-s)-1;
      len = opus_encode_native(enc, buf, frame_size, tmp_data, curr_max);
      if (len<0)
      {
         RESTORE_STACK;
         return len;
      }
      /* We need to use the repacketizer to add the self-delimiting lengths
         while taking into account the fact that the encoder can now return
         more than one frame at a time (e.g. 60 ms CELT-only) */
      opus_repacketizer_cat(&rp, tmp_data, len);
      len = opus_repacketizer_out_range_impl(&rp, 0, opus_repacketizer_get_nb_frames(&rp), data, max_data_bytes-tot_size, s != st->layout.nb_streams-1);
      data += len;
      tot_size += len;
   }
   RESTORE_STACK;
   return tot_size;

}

#ifdef FIXED_POINT

#ifndef DISABLE_FLOAT_API
int opus_multistream_encode_float(
    OpusMSEncoder *st,
    const float *pcm,
    int frame_size,
    unsigned char *data,
    int max_data_bytes
)
{
   int i, ret;
   VARDECL(opus_int16, in);
   ALLOC_STACK;

   ALLOC(in, frame_size*st->layout.nb_channels, opus_int16);

   for (i=0;i<frame_size*st->layout.nb_channels;i++)
      in[i] = FLOAT2INT16(pcm[i]);
   ret = opus_multistream_encode(st, in, frame_size, data, max_data_bytes);
   RESTORE_STACK;
   return ret;
}
#endif

#else

int opus_multistream_encode(
    OpusMSEncoder *st,
    const opus_int16 *pcm,
    int frame_size,
    unsigned char *data,
    int max_data_bytes
)
{
   int i, ret;
   VARDECL(float, in);
   ALLOC_STACK;

   ALLOC(in, frame_size*st->layout.nb_channels, float);

   for (i=0;i<frame_size*st->layout.nb_channels;i++)
      in[i] = (1./32768)*pcm[i];
   ret = opus_multistream_encode_float(st, in, frame_size, data, max_data_bytes);
   RESTORE_STACK;
   return ret;
}

#endif

int opus_multistream_encoder_ctl(OpusMSEncoder *st, int request, ...)
{
   va_list ap;
   int coupled_size, mono_size;
   char *ptr;
   int ret = OPUS_OK;

   va_start(ap, request);

   coupled_size = opus_encoder_get_size(2);
   mono_size = opus_encoder_get_size(1);
   ptr = (char*)st + align(sizeof(OpusMSEncoder));
   switch (request)
   {
   case OPUS_SET_BITRATE_REQUEST:
   {
      int chan, s;
      opus_int32 value = va_arg(ap, opus_int32);
      chan = st->layout.nb_streams + st->layout.nb_coupled_streams;
      value /= chan;
      for (s=0;s<st->layout.nb_streams;s++)
      {
         OpusEncoder *enc;
         enc = (OpusEncoder*)ptr;
         opus_encoder_ctl(enc, request, value * (s < st->layout.nb_coupled_streams ? 2 : 1));
      }
   }
   break;
   case OPUS_GET_BITRATE_REQUEST:
   {
      int s;
      opus_int32 *value = va_arg(ap, opus_int32*);
      *value = 0;
      for (s=0;s<st->layout.nb_streams;s++)
      {
         opus_int32 rate;
         OpusEncoder *enc;
         enc = (OpusEncoder*)ptr;
         opus_encoder_ctl(enc, request, &rate);
         *value += rate;
      }
   }
   break;
   case OPUS_GET_VBR_REQUEST:
   case OPUS_GET_APPLICATION_REQUEST:
   case OPUS_GET_BANDWIDTH_REQUEST:
   case OPUS_GET_COMPLEXITY_REQUEST:
   case OPUS_GET_PACKET_LOSS_PERC_REQUEST:
   case OPUS_GET_DTX_REQUEST:
   case OPUS_GET_VOICE_RATIO_REQUEST:
   case OPUS_GET_VBR_CONSTRAINT_REQUEST:
   case OPUS_GET_SIGNAL_REQUEST:
   case OPUS_GET_LOOKAHEAD_REQUEST:
   case OPUS_GET_INBAND_FEC_REQUEST:
   {
      OpusEncoder *enc;
      /* For int32* GET params, just query the first stream */
      opus_int32 *value = va_arg(ap, opus_int32*);
      enc = (OpusEncoder*)ptr;
      ret = opus_encoder_ctl(enc, request, value);
   }
   break;
   case OPUS_GET_FINAL_RANGE_REQUEST:
   {
      int s;
      opus_uint32 *value = va_arg(ap, opus_uint32*);
      opus_uint32 tmp;
      *value=0;
      for (s=0;s<st->layout.nb_streams;s++)
      {
         OpusEncoder *enc;
         enc = (OpusEncoder*)ptr;
         if (s < st->layout.nb_coupled_streams)
            ptr += align(coupled_size);
         else
            ptr += align(mono_size);
         ret = opus_encoder_ctl(enc, request, &tmp);
         if (ret != OPUS_OK) break;
         *value ^= tmp;
      }
   }
   break;
   case OPUS_SET_COMPLEXITY_REQUEST:
   case OPUS_SET_VBR_REQUEST:
   case OPUS_SET_VBR_CONSTRAINT_REQUEST:
   case OPUS_SET_BANDWIDTH_REQUEST:
   case OPUS_SET_SIGNAL_REQUEST:
   case OPUS_SET_APPLICATION_REQUEST:
   case OPUS_SET_INBAND_FEC_REQUEST:
   case OPUS_SET_PACKET_LOSS_PERC_REQUEST:
   case OPUS_SET_DTX_REQUEST:
   case OPUS_SET_FORCE_MODE_REQUEST:
   {
      int s;
      /* This works for int32 params */
      opus_int32 value = va_arg(ap, opus_int32);
      for (s=0;s<st->layout.nb_streams;s++)
      {
         OpusEncoder *enc;

         enc = (OpusEncoder*)ptr;
         if (s < st->layout.nb_coupled_streams)
            ptr += align(coupled_size);
         else
            ptr += align(mono_size);
         ret = opus_encoder_ctl(enc, request, value);
         if (ret != OPUS_OK)
            break;
      }
   }
   break;
   case OPUS_MULTISTREAM_GET_ENCODER_STATE_REQUEST:
   {
      int s;
      opus_int32 stream_id;
      OpusEncoder **value;
      stream_id = va_arg(ap, opus_int32);
      if (stream_id<0 || stream_id >= st->layout.nb_streams)
         ret = OPUS_BAD_ARG;
      value = va_arg(ap, OpusEncoder**);
      for (s=0;s<stream_id;s++)
      {
         if (s < st->layout.nb_coupled_streams)
            ptr += align(coupled_size);
         else
            ptr += align(mono_size);
      }
      *value = (OpusEncoder*)ptr;
   }
      break;
   default:
      ret = OPUS_UNIMPLEMENTED;
      break;
   }

   va_end(ap);
   return ret;
}

void opus_multistream_encoder_destroy(OpusMSEncoder *st)
{
    opus_free(st);
}


/* DECODER */

opus_int32 opus_multistream_decoder_get_size(int nb_streams, int nb_coupled_streams)
{
   int coupled_size;
   int mono_size;

   if(nb_streams<1||nb_coupled_streams>nb_streams||nb_coupled_streams<0)return 0;
   coupled_size = opus_decoder_get_size(2);
   mono_size = opus_decoder_get_size(1);
   return align(sizeof(OpusMSDecoder))
         + nb_coupled_streams * align(coupled_size)
         + (nb_streams-nb_coupled_streams) * align(mono_size);
}

int opus_multistream_decoder_init(
      OpusMSDecoder *st,
      opus_int32 Fs,
      int channels,
      int streams,
      int coupled_streams,
      unsigned char *mapping
)
{
   int coupled_size;
   int mono_size;
   int i, ret;
   char *ptr;

   st->layout.nb_channels = channels;
   st->layout.nb_streams = streams;
   st->layout.nb_coupled_streams = coupled_streams;

   for (i=0;i<st->layout.nb_channels;i++)
      st->layout.mapping[i] = mapping[i];
   if (!validate_layout(&st->layout))
      return OPUS_BAD_ARG;

   ptr = (char*)st + align(sizeof(OpusMSDecoder));
   coupled_size = opus_decoder_get_size(2);
   mono_size = opus_decoder_get_size(1);

   for (i=0;i<st->layout.nb_coupled_streams;i++)
   {
      ret=opus_decoder_init((OpusDecoder*)ptr, Fs, 2);
      if(ret!=OPUS_OK)return ret;
      ptr += align(coupled_size);
   }
   for (;i<st->layout.nb_streams;i++)
   {
      ret=opus_decoder_init((OpusDecoder*)ptr, Fs, 1);
      if(ret!=OPUS_OK)return ret;
      ptr += align(mono_size);
   }
   return OPUS_OK;
}


OpusMSDecoder *opus_multistream_decoder_create(
      opus_int32 Fs,
      int channels,
      int streams,
      int coupled_streams,
      unsigned char *mapping,
      int *error
)
{
   int ret;
   OpusMSDecoder *st = (OpusMSDecoder *)opus_alloc(opus_multistream_decoder_get_size(streams, coupled_streams));
   if (st==NULL)
   {
      if (error)
         *error = OPUS_ALLOC_FAIL;
      return NULL;
   }
   ret = opus_multistream_decoder_init(st, Fs, channels, streams, coupled_streams, mapping);
   if (error)
      *error = ret;
   if (ret != OPUS_OK)
   {
      opus_free(st);
      st = NULL;
   }
   return st;


}

static int opus_multistream_decode_native(
      OpusMSDecoder *st,
      const unsigned char *data,
      int len,
      opus_val16 *pcm,
      int frame_size,
      int decode_fec
)
{
   int coupled_size;
   int mono_size;
   int s, i, c;
   char *ptr;
   int do_plc=0;
   VARDECL(opus_val16, buf);
   ALLOC_STACK;

   ALLOC(buf, 2*frame_size, opus_val16);
   ptr = (char*)st + align(sizeof(OpusMSDecoder));
   coupled_size = opus_decoder_get_size(2);
   mono_size = opus_decoder_get_size(1);

   if (len==0)
      do_plc = 1;
   if (len < 0)
      return OPUS_BAD_ARG;
   if (!do_plc && len < 2*st->layout.nb_streams-1)
      return OPUS_INVALID_PACKET;
   for (s=0;s<st->layout.nb_streams;s++)
   {
      OpusDecoder *dec;
      int packet_offset, ret;

      dec = (OpusDecoder*)ptr;
      ptr += (s < st->layout.nb_coupled_streams) ? align(coupled_size) : align(mono_size);

      if (!do_plc && len<=0)
      {
         RESTORE_STACK;
         return OPUS_INVALID_PACKET;
      }
      packet_offset = 0;
      ret = opus_decode_native(dec, data, len, buf, frame_size, decode_fec, s!=st->layout.nb_streams-1, &packet_offset);
      data += packet_offset;
      len -= packet_offset;
      if (ret > frame_size)
      {
         RESTORE_STACK;
         return OPUS_BUFFER_TOO_SMALL;
      }
      if (s>0 && ret != frame_size)
      {
         RESTORE_STACK;
         return OPUS_INVALID_PACKET;
      }
      if (ret <= 0)
      {
         RESTORE_STACK;
         return ret;
      }
      frame_size = ret;
      if (s < st->layout.nb_coupled_streams)
      {
         int chan, prev;
         prev = -1;
         /* Copy "left" audio to the channel(s) where it belongs */
         while ( (chan = get_left_channel(&st->layout, s, prev)) != -1)
         {
            for (i=0;i<frame_size;i++)
               pcm[st->layout.nb_channels*i+chan] = buf[2*i];
            prev = chan;
         }
         prev = -1;
         /* Copy "right" audio to the channel(s) where it belongs */
         while ( (chan = get_right_channel(&st->layout, s, prev)) != -1)
         {
            for (i=0;i<frame_size;i++)
               pcm[st->layout.nb_channels*i+chan] = buf[2*i+1];
            prev = chan;
         }
      } else {
         int chan, prev;
         prev = -1;
         /* Copy audio to the channel(s) where it belongs */
         while ( (chan = get_mono_channel(&st->layout, s, prev)) != -1)
         {
            for (i=0;i<frame_size;i++)
               pcm[st->layout.nb_channels*i+chan] = buf[i];
            prev = chan;
         }
      }
   }
   /* Handle muted channels */
   for (c=0;c<st->layout.nb_channels;c++)
   {
      if (st->layout.mapping[c] == 255)
      {
         for (i=0;i<frame_size;i++)
            pcm[st->layout.nb_channels*i+c] = 0;
      }
   }
   RESTORE_STACK;
   return frame_size;
}

#ifdef FIXED_POINT
int opus_multistream_decode(
      OpusMSDecoder *st,
      const unsigned char *data,
      int len,
      opus_int16 *pcm,
      int frame_size,
      int decode_fec
)
{
   return opus_multistream_decode_native(st, data, len, pcm, frame_size, decode_fec);
}

#ifndef DISABLE_FLOAT_API
int opus_multistream_decode_float(OpusMSDecoder *st, const unsigned char *data,
      int len, float *pcm, int frame_size, int decode_fec)
{
   VARDECL(opus_int16, out);
   int ret, i;
   ALLOC_STACK;

   ALLOC(out, frame_size*st->layout.nb_channels, opus_int16);

   ret = opus_multistream_decode_native(st, data, len, out, frame_size, decode_fec);
   if (ret > 0)
   {
      for (i=0;i<ret*st->layout.nb_channels;i++)
         pcm[i] = (1./32768.)*(out[i]);
   }
   RESTORE_STACK;
   return ret;
}
#endif

#else

int opus_multistream_decode(OpusMSDecoder *st, const unsigned char *data,
      int len, opus_int16 *pcm, int frame_size, int decode_fec)
{
   VARDECL(float, out);
   int ret, i;
   ALLOC_STACK;

   ALLOC(out, frame_size*st->layout.nb_channels, float);

   ret = opus_multistream_decode_native(st, data, len, out, frame_size, decode_fec);
   if (ret > 0)
   {
      for (i=0;i<ret*st->layout.nb_channels;i++)
         pcm[i] = FLOAT2INT16(out[i]);
   }
   RESTORE_STACK;
   return ret;
}

int opus_multistream_decode_float(
      OpusMSDecoder *st,
      const unsigned char *data,
      int len,
      float *pcm,
      int frame_size,
      int decode_fec
)
{
   return opus_multistream_decode_native(st, data, len, pcm, frame_size, decode_fec);
}
#endif

int opus_multistream_decoder_ctl(OpusMSDecoder *st, int request, ...)
{
   va_list ap;
   int coupled_size, mono_size;
   char *ptr;
   int ret = OPUS_OK;

   va_start(ap, request);

   coupled_size = opus_decoder_get_size(2);
   mono_size = opus_decoder_get_size(1);
   ptr = (char*)st + align(sizeof(OpusMSDecoder));
   switch (request)
   {
       case OPUS_GET_BANDWIDTH_REQUEST:
       {
          OpusDecoder *dec;
          /* For int32* GET params, just query the first stream */
          opus_int32 *value = va_arg(ap, opus_int32*);
          dec = (OpusDecoder*)ptr;
          ret = opus_decoder_ctl(dec, request, value);
       }
       break;
       case OPUS_GET_FINAL_RANGE_REQUEST:
       {
          int s;
          opus_uint32 *value = va_arg(ap, opus_uint32*);
          opus_uint32 tmp;
          *value = 0;
          for (s=0;s<st->layout.nb_streams;s++)
          {
             OpusDecoder *dec;
             dec = (OpusDecoder*)ptr;
             if (s < st->layout.nb_coupled_streams)
                ptr += align(coupled_size);
             else
                ptr += align(mono_size);
             ret = opus_decoder_ctl(dec, request, &tmp);
             if (ret != OPUS_OK) break;
             *value ^= tmp;
          }
       }
       break;
       case OPUS_RESET_STATE:
       {
          int s;
          for (s=0;s<st->layout.nb_streams;s++)
          {
             OpusDecoder *dec;

             dec = (OpusDecoder*)ptr;
             if (s < st->layout.nb_coupled_streams)
                ptr += align(coupled_size);
             else
                ptr += align(mono_size);
             ret = opus_decoder_ctl(dec, OPUS_RESET_STATE);
             if (ret != OPUS_OK)
                break;
          }
       }
       break;
       case OPUS_MULTISTREAM_GET_DECODER_STATE_REQUEST:
       {
          int s;
          opus_int32 stream_id;
          OpusDecoder **value;
          stream_id = va_arg(ap, opus_int32);
          if (stream_id<0 || stream_id >= st->layout.nb_streams)
             ret = OPUS_BAD_ARG;
          value = va_arg(ap, OpusDecoder**);
          for (s=0;s<stream_id;s++)
          {
             if (s < st->layout.nb_coupled_streams)
                ptr += align(coupled_size);
             else
                ptr += align(mono_size);
          }
          *value = (OpusDecoder*)ptr;
       }
          break;
       default:
          ret = OPUS_UNIMPLEMENTED;
       break;
   }

   va_end(ap);
   return ret;
}


void opus_multistream_decoder_destroy(OpusMSDecoder *st)
{
    opus_free(st);
}
