1// Copyright (c) 2012 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef MEDIA_AUDIO_SHARED_MEMORY_UTIL_H_
6#define MEDIA_AUDIO_SHARED_MEMORY_UTIL_H_
7
8#include "base/basictypes.h"
9#include "base/memory/shared_memory.h"
10#include "media/base/media_export.h"
11
12namespace media {
13
14// Value sent by the controller to the renderer in low-latency mode
15// indicating that the stream is paused.
16enum { kPauseMark = -1 };
17
18// Functions that handle data buffer passed between processes in the shared
19// memory.  Called on both IPC sides.  These are necessary because the shared
20// memory has a layout: the last word in the block is the data size in bytes.
21
22MEDIA_EXPORT uint32 TotalSharedMemorySizeInBytes(uint32 packet_size);
23MEDIA_EXPORT uint32 PacketSizeInBytes(uint32 shared_memory_created_size);
24MEDIA_EXPORT uint32 GetActualDataSizeInBytes(base::SharedMemory* shared_memory,
25                                             uint32 packet_size);
26MEDIA_EXPORT void SetActualDataSizeInBytes(base::SharedMemory* shared_memory,
27                                           uint32 packet_size,
28                                           uint32 actual_data_size);
29MEDIA_EXPORT void SetActualDataSizeInBytes(void* shared_memory_ptr,
30                                           uint32 packet_size,
31                                           uint32 actual_data_size);
32MEDIA_EXPORT void SetUnknownDataSize(base::SharedMemory* shared_memory,
33                                     uint32 packet_size);
34MEDIA_EXPORT bool IsUnknownDataSize(base::SharedMemory* shared_memory,
35                                    uint32 packet_size);
36
37}  // namespace media
38
39#endif  // MEDIA_AUDIO_SHARED_MEMORY_UTIL_H_
40