Splits out the Opus multi-stream encoder and decoder
diff --git a/src/opus_multistream_encoder.c b/src/opus_multistream_encoder.c
new file mode 100644
index 0000000..c5f37a0
--- /dev/null
+++ b/src/opus_multistream_encoder.c
@@ -0,0 +1,526 @@
+/* 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.
+
+   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"
+
+struct OpusMSEncoder {
+   ChannelLayout layout;
+   int bitrate;
+   /* Encoder states go here */
+};
+
+#ifdef FIXED_POINT
+#define opus_encode_native opus_encode
+#else
+#define opus_encode_native opus_encode_float
+#endif
+
+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,
+      const unsigned char *mapping,
+      int application
+)
+{
+   int coupled_size;
+   int mono_size;
+   int i, ret;
+   char *ptr;
+
+   if ((channels>255) || (channels<1) || (coupled_streams>streams) ||
+       (coupled_streams+streams>255) || (streams<1) || (coupled_streams<0))
+      return OPUS_BAD_ARG;
+
+   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++)
+   {
+      ret = opus_encoder_init((OpusEncoder*)ptr, Fs, 2, application);
+      if(ret!=OPUS_OK)return ret;
+      ptr += align(coupled_size);
+   }
+   for (;i<st->layout.nb_streams;i++)
+   {
+      ret = opus_encoder_init((OpusEncoder*)ptr, Fs, 1, application);
+      if(ret!=OPUS_OK)return ret;
+      ptr += align(mono_size);
+   }
+   return OPUS_OK;
+}
+
+OpusMSEncoder *opus_multistream_encoder_create(
+      opus_int32 Fs,
+      int channels,
+      int streams,
+      int coupled_streams,
+      const unsigned char *mapping,
+      int application,
+      int *error
+)
+{
+   int ret;
+   OpusMSEncoder *st;
+   if ((channels>255) || (channels<1) || (coupled_streams>streams) ||
+       (coupled_streams+streams>255) || (streams<1) || (coupled_streams<0))
+   {
+      if (error)
+         *error = OPUS_BAD_ARG;
+      return NULL;
+   }
+   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;
+}
+
+typedef void (*opus_copy_channel_in_func)(
+  opus_val16 *dst,
+  int dst_stride,
+  const void *src,
+  int src_stride,
+  int src_channel,
+  int frame_size
+);
+
+/* Max size in case the encoder decides to return three frames */
+#define MS_FRAME_TMP (3*1275+7)
+static int opus_multistream_encode_native
+(
+    OpusMSEncoder *st,
+    opus_copy_channel_in_func copy_channel_in,
+    const void *pcm,
+    int frame_size,
+    unsigned char *data,
+    opus_int32 max_data_bytes
+)
+{
+   opus_int32 Fs;
+   int coupled_size;
+   int mono_size;
+   int s;
+   char *ptr;
+   int tot_size;
+   VARDECL(opus_val16, buf);
+   unsigned char tmp_data[MS_FRAME_TMP];
+   OpusRepacketizer rp;
+   ALLOC_STACK;
+
+   ptr = (char*)st + align(sizeof(OpusMSEncoder));
+   opus_encoder_ctl((OpusEncoder*)ptr, OPUS_GET_SAMPLE_RATE(&Fs));
+   /* Validate frame_size before using it to allocate stack space.
+      This mirrors the checks in opus_encode[_float](). */
+   if (400*frame_size != Fs && 200*frame_size != Fs &&
+       100*frame_size != Fs &&  50*frame_size != Fs &&
+        25*frame_size != Fs &&  50*frame_size != 3*Fs)
+   {
+      RESTORE_STACK;
+      return OPUS_BAD_ARG;
+   }
+   ALLOC(buf, 2*frame_size, opus_val16);
+   coupled_size = opus_encoder_get_size(2);
+   mono_size = opus_encoder_get_size(1);
+
+   if (max_data_bytes < 4*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);
+         (*copy_channel_in)(buf, 2,
+            pcm, st->layout.nb_channels, left, frame_size);
+         (*copy_channel_in)(buf+1, 2,
+            pcm, st->layout.nb_channels, right, frame_size);
+         ptr += align(coupled_size);
+      } else {
+         int chan = get_mono_channel(&st->layout, s, -1);
+         (*copy_channel_in)(buf, 1,
+            pcm, st->layout.nb_channels, chan, frame_size);
+         ptr += align(mono_size);
+      }
+      /* number of bytes left (+Toc) */
+      curr_max = max_data_bytes - tot_size;
+      /* Reserve three bytes for the last stream and four for the others */
+      curr_max -= IMAX(0,4*(st->layout.nb_streams-s-1)-1);
+      curr_max = IMIN(curr_max,MS_FRAME_TMP);
+      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;
+
+}
+
+#if !defined(DISABLE_FLOAT_API)
+static void opus_copy_channel_in_float(
+  opus_val16 *dst,
+  int dst_stride,
+  const void *src,
+  int src_stride,
+  int src_channel,
+  int frame_size
+)
+{
+   const float *float_src;
+   int i;
+   float_src = (const float *)src;
+   for (i=0;i<frame_size;i++)
+#if defined(FIXED_POINT)
+      dst[i*dst_stride] = FLOAT2INT16(float_src[i*src_stride+src_channel]);
+#else
+      dst[i*dst_stride] = float_src[i*src_stride+src_channel];
+#endif
+}
+#endif
+
+static void opus_copy_channel_in_short(
+  opus_val16 *dst,
+  int dst_stride,
+  const void *src,
+  int src_stride,
+  int src_channel,
+  int frame_size
+)
+{
+   const opus_int16 *short_src;
+   int i;
+   short_src = (const opus_int16 *)src;
+   for (i=0;i<frame_size;i++)
+#if defined(FIXED_POINT)
+      dst[i*dst_stride] = short_src[i*src_stride+src_channel];
+#else
+      dst[i*dst_stride] = (1/32768.f)*short_src[i*src_stride+src_channel];
+#endif
+}
+
+#ifdef FIXED_POINT
+int opus_multistream_encode(
+    OpusMSEncoder *st,
+    const opus_val16 *pcm,
+    int frame_size,
+    unsigned char *data,
+    opus_int32 max_data_bytes
+)
+{
+   return opus_multistream_encode_native(st, opus_copy_channel_in_short,
+      pcm, frame_size, data, max_data_bytes);
+}
+
+#ifndef DISABLE_FLOAT_API
+int opus_multistream_encode_float(
+    OpusMSEncoder *st,
+    const float *pcm,
+    int frame_size,
+    unsigned char *data,
+    opus_int32 max_data_bytes
+)
+{
+   return opus_multistream_encode_native(st, opus_copy_channel_in_float,
+      pcm, frame_size, data, max_data_bytes);
+}
+#endif
+
+#else
+
+int opus_multistream_encode_float
+(
+    OpusMSEncoder *st,
+    const opus_val16 *pcm,
+    int frame_size,
+    unsigned char *data,
+    opus_int32 max_data_bytes
+)
+{
+   return opus_multistream_encode_native(st, opus_copy_channel_in_float,
+      pcm, frame_size, data, max_data_bytes);
+}
+
+int opus_multistream_encode(
+    OpusMSEncoder *st,
+    const opus_int16 *pcm,
+    int frame_size,
+    unsigned char *data,
+    opus_int32 max_data_bytes
+)
+{
+   return opus_multistream_encode_native(st, opus_copy_channel_in_short,
+      pcm, frame_size, data, max_data_bytes);
+}
+#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;
+         if (s < st->layout.nb_coupled_streams)
+            ptr += align(coupled_size);
+         else
+            ptr += align(mono_size);
+         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;
+         if (s < st->layout.nb_coupled_streams)
+            ptr += align(coupled_size);
+         else
+            ptr += align(mono_size);
+         opus_encoder_ctl(enc, request, &rate);
+         *value += rate;
+      }
+   }
+   break;
+   case OPUS_GET_LSB_DEPTH_REQUEST:
+   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_SAMPLE_RATE_REQUEST:
+   case OPUS_GET_INBAND_FEC_REQUEST:
+   case OPUS_GET_FORCE_CHANNELS_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_LSB_DEPTH_REQUEST:
+   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:
+   case OPUS_SET_FORCE_CHANNELS_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);
+}
+
+