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1 // Copyright (c) 2016 The Chromium Authors. All rights reserved. | 1 // Copyright (c) 2016 The Chromium Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 #ifndef DEVICE_GAMEPAD_SHARED_BUFFER_H_ | 5 #ifndef DEVICE_GAMEPAD_SHARED_BUFFER_H_ |
6 #define DEVICE_GAMEPAD_SHARED_BUFFER_H_ | 6 #define DEVICE_GAMEPAD_SHARED_BUFFER_H_ |
7 | 7 |
8 #include "base/memory/shared_memory.h" | 8 #include "base/memory/shared_memory.h" |
9 #include "device/base/synchronization/shared_memory_seqlock_buffer.h" | 9 #include "device/base/synchronization/shared_memory_seqlock_buffer.h" |
10 #include "device/gamepad/gamepad_export.h" | 10 #include "device/gamepad/gamepad_export.h" |
11 #include "third_party/WebKit/public/platform/WebGamepads.h" | 11 #include "device/gamepad/public/cpp/gamepads.h" |
12 | 12 |
13 namespace device { | 13 namespace device { |
14 | 14 |
15 /* | 15 /* |
16 | 16 |
17 GamepadHardwareBuffer is stored in shared memory that's shared between the | 17 GamepadHardwareBuffer is stored in shared memory that's shared between the |
18 browser which does the hardware polling, and the various consumers of the | 18 browser which does the hardware polling, and the various consumers of the |
19 gamepad state (renderers and NaCl plugins). The performance characteristics are | 19 gamepad state (renderers and NaCl plugins). The performance characteristics are |
20 that we want low latency (so would like to avoid explicit communication via IPC | 20 that we want low latency (so would like to avoid explicit communication via IPC |
21 between producer and consumer) and relatively large data size. | 21 between producer and consumer) and relatively large data size. |
22 | 22 |
23 Writer and reader operate on the same buffer assuming contention is low, and | 23 Writer and reader operate on the same buffer assuming contention is low, and |
24 contention is detected by using the associated SeqLock. | 24 contention is detected by using the associated SeqLock. |
25 | 25 |
26 */ | 26 */ |
27 | 27 |
28 typedef SharedMemorySeqLockBuffer<blink::WebGamepads> GamepadHardwareBuffer; | 28 typedef SharedMemorySeqLockBuffer<Gamepads> GamepadHardwareBuffer; |
29 | 29 |
30 class DEVICE_GAMEPAD_EXPORT GamepadSharedBuffer { | 30 class DEVICE_GAMEPAD_EXPORT GamepadSharedBuffer { |
31 public: | 31 public: |
32 GamepadSharedBuffer(); | 32 GamepadSharedBuffer(); |
33 ~GamepadSharedBuffer(); | 33 ~GamepadSharedBuffer(); |
34 | 34 |
35 base::SharedMemory* shared_memory(); | 35 base::SharedMemory* shared_memory(); |
36 blink::WebGamepads* buffer(); | 36 Gamepads* buffer(); |
37 GamepadHardwareBuffer* hardware_buffer(); | 37 GamepadHardwareBuffer* hardware_buffer(); |
38 | 38 |
39 void WriteBegin(); | 39 void WriteBegin(); |
40 void WriteEnd(); | 40 void WriteEnd(); |
41 | 41 |
42 private: | 42 private: |
43 base::SharedMemory shared_memory_; | 43 base::SharedMemory shared_memory_; |
44 GamepadHardwareBuffer* hardware_buffer_; | 44 GamepadHardwareBuffer* hardware_buffer_; |
45 }; | 45 }; |
46 | 46 |
47 } // namespace device | 47 } // namespace device |
48 | 48 |
49 #endif // DEVICE_GAMEPAD_SHARED_BUFFER_H_ | 49 #endif // DEVICE_GAMEPAD_SHARED_BUFFER_H_ |
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