Introduce shared_memory_support media target for PPAPI

media/audio/shared_memory_util.h

+// Copyright (c) 2012 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 MEDIA_AUDIO_SHARED_MEMORY_UTIL_H_
+#define MEDIA_AUDIO_SHARED_MEMORY_UTIL_H_
+
+#include "base/basictypes.h"
+#include "base/shared_memory.h"
+#include "media/base/media_export.h"
+
+namespace media {
+
+// Value sent by the controller to the renderer in low-latency mode
+// indicating that the stream is paused.
+enum { kPauseMark = -1 };
+
+// Functions that handle data buffer passed between processes in the shared
+// memory.  Called on both IPC sides.  These are necessary because the shared
+// memory has a layout: the last word in the block is the data size in bytes.
+
+MEDIA_EXPORT uint32 TotalSharedMemorySizeInBytes(uint32 packet_size);
+MEDIA_EXPORT uint32 PacketSizeSizeInBytes(uint32 shared_memory_created_size);

[dmichael (off chromium), 2012/08/23 21:15:53]

drive-by...  is this really meant to have SizeSize, or should it be
PacketSizeInBytes? The name is confusing to me.

[DaleCurtis, 2012/08/23 21:55:15]

Hah, I didn't even notice that; it's a copy paste from the old version. I'll fix
the two callers to that function. Done.

+MEDIA_EXPORT uint32 GetActualDataSizeInBytes(base::SharedMemory* shared_memory,
+                                             uint32 shared_memory_size);
+MEDIA_EXPORT void SetActualDataSizeInBytes(base::SharedMemory* shared_memory,
+                                           uint32 shared_memory_size,
+                                           uint32 actual_data_size);
+MEDIA_EXPORT void SetActualDataSizeInBytes(void* shared_memory_ptr,
+                                           uint32 shared_memory_size,
+                                           uint32 actual_data_size);
+MEDIA_EXPORT void SetUnknownDataSize(base::SharedMemory* shared_memory,
+                                     uint32 shared_memory_size);
+MEDIA_EXPORT bool IsUnknownDataSize(base::SharedMemory* shared_memory,
+                                    uint32 shared_memory_size);
+
+}  // namespace media
+
+#endif  // MEDIA_AUDIO_SHARED_MEMORY_UTIL_H_