Initial audio implementation.

ppapi/shared_impl/audio_impl.h

Index: ppapi/shared_impl/audio_impl.h
===================================================================
--- ppapi/shared_impl/audio_impl.h	(revision 0)
+++ ppapi/shared_impl/audio_impl.h	(revision 0)
@@ -0,0 +1,85 @@
+// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef PPAPI_SHARED_IMPL_AUDIO_IMPL_H_
+#define PPAPI_SHARED_IMPL_AUDIO_IMPL_H_
+
+#include "base/scoped_ptr.h"
+#include "base/simple_thread.h"
+#include "base/shared_memory.h"
+#include "base/sync_socket.h"
+#include "ppapi/c/dev/ppb_audio_dev.h"
+
+namespace pp {
+namespace shared_impl {
+
+// Implements the logic to map shared memory and run the audio thread signaled
+// from the sync socket. Both the proxy and the renderer implementation use
+// this code.
+class AudioImpl : public base::DelegateSimpleThread::Delegate {
+ public:
+  AudioImpl();
+  virtual ~AudioImpl();
+
+  bool playing() const { return playing_; }
+
+  // Sets the callback information that the background thread will use. This
+  // is optional. Without a callback, the thread will not be run. This
+  // non-callback mode is used in the renderer with the proxy, since the proxy
+  // handles the callback entirely within the plugin process.
+  void SetCallback(PPB_Audio_Callback callback, void* user_data);
+
+  // Configures the current state to be playing or not. The caller is
+  // responsible for ensuring the new state is the opposite of the current one.
+  //
+  // This is the implementation for PPB_Audio.Start/StopPlayback, except that
+  // it does not actually notify the audio system to stop playback, it just
+  // configures our object to stop generating callbacks. The actual stop
+  // playback request will be done in the derived classes and will be different
+  // from the proxy and the renderer.
+  void SetStartPlaybackState();
+  void SetStopPlaybackState();
+
+  // Sets the shared memory and socket handles. This will automatically start
+  // playback if we're currently set to play.
+  void SetStreamInfo(base::SharedMemoryHandle shared_memory_handle,
+                     size_t shared_memory_size,
+                     base::SyncSocket::Handle socket_handle);
+
+ private:
+  // Starts execution of the audio thread.
+  void StartThread();
+
+  // DelegateSimpleThread::Delegate implementation. Run on the audio thread.
+  void Run();
+
+  // True if playing the stream.
+  bool playing_;
+
+  // Socket used to notify us when audio is ready to accept new samples. This
+  // pointer is created in StreamCreated().
+  scoped_ptr<base::SyncSocket> socket_;
+
+  // Sample buffer in shared memory. This pointer is created in
+  // StreamCreated(). The memory is only mapped when the audio thread is
+  // created.
+  scoped_ptr<base::SharedMemory> shared_memory_;
+
+  // The size of the sample buffer in bytes.
+  size_t shared_memory_size_;
+
+  // When the callback is set, this thread is spawned for calling it.
+  scoped_ptr<base::DelegateSimpleThread> audio_thread_;
+
+  // Callback to call when audio is ready to accept new samples.
+  volatile PPB_Audio_Callback callback_;

[piman, 2010/12/01 23:27:10]

Why volatile ?

[brettw, 2010/12/02 00:00:53]

I just copied this from the old code. I don't think it actually gets us anything
in this case so I removed it.

+
+  // User data pointer passed verbatim to the callback function.
+  void* user_data_;
+};
+
+}  // namespace shared_impl
+}  // namespace pp
+
+#endif  // PPAPI_SHARED_IMPL_AUDIO_IMPL_H_