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_SERVICE_COMMON_DECODER_H_
6#define GPU_COMMAND_BUFFER_SERVICE_COMMON_DECODER_H_
7
8#include <map>
9#include <stack>
10#include <string>
11#include "base/memory/linked_ptr.h"
12#include "base/memory/scoped_ptr.h"
13#include "gpu/command_buffer/common/buffer.h"
14#include "gpu/command_buffer/service/cmd_parser.h"
15#include "gpu/gpu_export.h"
16
17namespace gpu {
18
19class CommandBufferEngine;
20
21// This class is a helper base class for implementing the common parts of the
22// o3d/gl2 command buffer decoder.
23class GPU_EXPORT CommonDecoder : NON_EXPORTED_BASE(public AsyncAPIInterface) {
24 public:
25  typedef error::Error Error;
26
27  static const unsigned int kMaxStackDepth = 32;
28
29  // A bucket is a buffer to help collect memory across a command buffer. When
30  // creating a command buffer implementation of an existing API, sometimes that
31  // API has functions that take a pointer to data.  A good example is OpenGL's
32  // glBufferData. Because the data is separated between client and service,
33  // there are 2 ways to get this data across. 1 is to put all the data in
34  // shared memory. The problem with this is the data can be arbitarily large
35  // and the host OS may not support that much shared memory. Another solution
36  // is to shuffle memory across a little bit at a time, collecting it on the
37  // service side and when it is all there then call glBufferData. Buckets
38  // implement this second solution. Using the common commands, SetBucketSize,
39  // SetBucketData, SetBucketDataImmediate the client can fill a bucket. It can
40  // then call a command that uses that bucket (like BufferDataBucket in the
41  // GLES2 command buffer implementation).
42  //
43  // If you are designing an API from scratch you can avoid this need for
44  // Buckets by making your API always take an offset and a size
45  // similar to glBufferSubData.
46  //
47  // Buckets also help pass strings to/from the service. To return a string of
48  // arbitary size, the service puts the string in a bucket. The client can
49  // then query the size of a bucket and request sections of the bucket to
50  // be passed across shared memory.
51  class GPU_EXPORT Bucket {
52   public:
53    Bucket();
54    ~Bucket();
55
56    size_t size() const {
57      return size_;
58    }
59
60    // Gets a pointer to a section the bucket. Returns NULL if offset or size is
61    // out of range.
62    void* GetData(size_t offset, size_t size) const;
63
64    template <typename T>
65    T GetDataAs(size_t offset, size_t size) const {
66      return reinterpret_cast<T>(GetData(offset, size));
67    }
68
69    // Sets the size of the bucket.
70    void SetSize(size_t size);
71
72    // Sets a part of the bucket.
73    // Returns false if offset or size is out of range.
74    bool SetData(const void* src, size_t offset, size_t size);
75
76    // Sets the bucket data from a string. Strings are passed NULL terminated to
77    // distinguish between empty string and no string.
78    void SetFromString(const char* str);
79
80    // Gets the bucket data as a string. Strings are passed NULL terminated to
81    // distrinquish between empty string and no string. Returns False if there
82    // is no string.
83    bool GetAsString(std::string* str);
84
85   private:
86    bool OffsetSizeValid(size_t offset, size_t size) const {
87      size_t temp = offset + size;
88      return temp <= size_ && temp >= offset;
89    }
90
91    size_t size_;
92    ::scoped_ptr<int8[]> data_;
93
94    DISALLOW_COPY_AND_ASSIGN(Bucket);
95  };
96
97  CommonDecoder();
98  virtual ~CommonDecoder();
99
100  // Sets the engine, to get shared memory buffers from, and to set the token
101  // to.
102  void set_engine(CommandBufferEngine* engine) {
103    engine_ = engine;
104  }
105  CommandBufferEngine* engine() const { return engine_; }
106
107  // Creates a bucket. If the bucket already exists returns that bucket.
108  Bucket* CreateBucket(uint32 bucket_id);
109
110  // Gets a bucket. Returns NULL if the bucket does not exist.
111  Bucket* GetBucket(uint32 bucket_id) const;
112
113  // Gets the address of shared memory data, given a shared memory ID and an
114  // offset. Also checks that the size is consistent with the shared memory
115  // size.
116  // Parameters:
117  //   shm_id: the id of the shared memory buffer.
118  //   offset: the offset of the data in the shared memory buffer.
119  //   size: the size of the data.
120  // Returns:
121  //   NULL if shm_id isn't a valid shared memory buffer ID or if the size
122  //   check fails. Return a pointer to the data otherwise.
123  void* GetAddressAndCheckSize(unsigned int shm_id,
124                               unsigned int offset,
125                               unsigned int size);
126
127  // Typed version of GetAddressAndCheckSize.
128  template <typename T>
129  T GetSharedMemoryAs(unsigned int shm_id, unsigned int offset,
130                      unsigned int size) {
131    return static_cast<T>(GetAddressAndCheckSize(shm_id, offset, size));
132  }
133
134  // Get the actual shared memory buffer.
135  scoped_refptr<gpu::Buffer> GetSharedMemoryBuffer(unsigned int shm_id);
136
137 protected:
138  // Executes a common command.
139  // Parameters:
140  //    command: the command index.
141  //    arg_count: the number of CommandBufferEntry arguments.
142  //    cmd_data: the command data.
143  // Returns:
144  //   error::kNoError if no error was found, one of
145  //   error::Error otherwise.
146  error::Error DoCommonCommand(
147      unsigned int command,
148      unsigned int arg_count,
149      const void* cmd_data);
150
151  // Gets an name for a common command.
152  const char* GetCommonCommandName(cmd::CommandId command_id) const;
153
154 private:
155  // Generate a member function prototype for each command in an automated and
156  // typesafe way.
157  #define COMMON_COMMAND_BUFFER_CMD_OP(name)             \
158     error::Error Handle##name(                          \
159       uint32 immediate_data_size,                       \
160       const cmd::name& args);                           \
161
162  COMMON_COMMAND_BUFFER_CMDS(COMMON_COMMAND_BUFFER_CMD_OP)
163
164  #undef COMMON_COMMAND_BUFFER_CMD_OP
165
166  CommandBufferEngine* engine_;
167
168  typedef std::map<uint32, linked_ptr<Bucket> > BucketMap;
169  BucketMap buckets_;
170};
171
172}  // namespace gpu
173
174#endif  // GPU_COMMAND_BUFFER_SERVICE_COMMON_DECODER_H_
175
176