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 GPU_COMMAND_BUFFER_COMMON_COMMAND_BUFFER_H_
6#define GPU_COMMAND_BUFFER_COMMON_COMMAND_BUFFER_H_
7
8#include "gpu/command_buffer/common/buffer.h"
9#include "gpu/command_buffer/common/constants.h"
10#include "gpu/gpu_export.h"
11
12namespace base {
13class SharedMemory;
14}
15
16namespace gpu {
17
18// Common interface for CommandBuffer implementations.
19class GPU_EXPORT CommandBuffer {
20 public:
21  struct State {
22    State()
23        : num_entries(0),
24          get_offset(0),
25          put_offset(0),
26          token(-1),
27          error(error::kNoError),
28          context_lost_reason(error::kUnknown),
29          generation(0) {
30    }
31
32    // Size of the command buffer in command buffer entries.
33    int32 num_entries;
34
35    // The offset (in entries) from which the reader is reading.
36    int32 get_offset;
37
38    // The offset (in entries) at which the writer is writing.
39    int32 put_offset;
40
41    // The current token value. This is used by the writer to defer
42    // changes to shared memory objects until the reader has reached a certain
43    // point in the command buffer. The reader is responsible for updating the
44    // token value, for example in response to an asynchronous set token command
45    // embedded in the command buffer. The default token value is zero.
46    int32 token;
47
48    // Error status.
49    error::Error error;
50
51    // Lost context detail information.
52    error::ContextLostReason context_lost_reason;
53
54    // Generation index of this state. The generation index is incremented every
55    // time a new state is retrieved from the command processor, so that
56    // consistency can be kept even if IPC messages are processed out-of-order.
57    uint32 generation;
58  };
59
60  struct ConsoleMessage {
61    // An user supplied id.
62    int32 id;
63    // The message.
64    std::string message;
65  };
66
67  CommandBuffer() {
68  }
69
70  virtual ~CommandBuffer() {
71  }
72
73  // Check if a value is between a start and end value, inclusive, allowing
74  // for wrapping if start > end.
75  static bool InRange(int32 start, int32 end, int32 value) {
76    if (start <= end)
77      return start <= value && value <= end;
78    else
79      return start <= value || value <= end;
80  }
81
82  // Initialize the command buffer with the given size.
83  virtual bool Initialize() = 0;
84
85  // Returns the last state without synchronizing with the service.
86  virtual State GetLastState() = 0;
87
88  // Returns the last token without synchronizing with the service. Note that
89  // while you could just call GetLastState().token, GetLastState needs to be
90  // fast as it is called for every command where GetLastToken is only called
91  // by code that needs to know the last token so it can be slower but more up
92  // to date than GetLastState.
93  virtual int32 GetLastToken() = 0;
94
95  // The writer calls this to update its put offset. This ensures the reader
96  // sees the latest added commands, and will eventually process them. On the
97  // service side, commands are processed up to the given put_offset before
98  // subsequent Flushes on the same GpuChannel.
99  virtual void Flush(int32 put_offset) = 0;
100
101  // The writer calls this to wait until the current token is within a
102  // specific range, inclusive. Can return early if an error is generated.
103  virtual void WaitForTokenInRange(int32 start, int32 end) = 0;
104
105  // The writer calls this to wait until the current get offset is within a
106  // specific range, inclusive. Can return early if an error is generated.
107  virtual void WaitForGetOffsetInRange(int32 start, int32 end) = 0;
108
109  // Sets the buffer commands are read from.
110  // Also resets the get and put offsets to 0.
111  virtual void SetGetBuffer(int32 transfer_buffer_id) = 0;
112
113  // Create a transfer buffer of the given size. Returns its ID or -1 on
114  // error.
115  virtual scoped_refptr<gpu::Buffer> CreateTransferBuffer(size_t size,
116                                                          int32* id) = 0;
117
118  // Destroy a transfer buffer. The ID must be positive.
119  virtual void DestroyTransferBuffer(int32 id) = 0;
120
121// The NaCl Win64 build only really needs the struct definitions above; having
122// GetLastError declared would mean we'd have to also define it, and pull more
123// of gpu in to the NaCl Win64 build.
124#if !defined(NACL_WIN64)
125  // TODO(apatrick): this is a temporary optimization while skia is calling
126  // RendererGLContext::MakeCurrent prior to every GL call. It saves returning 6
127  // ints redundantly when only the error is needed for the CommandBufferProxy
128  // implementation.
129  virtual error::Error GetLastError();
130#endif
131
132 private:
133  DISALLOW_COPY_AND_ASSIGN(CommandBuffer);
134};
135
136}  // namespace gpu
137
138#endif  // GPU_COMMAND_BUFFER_COMMON_COMMAND_BUFFER_H_
139