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| 1 // Copyright 2014 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 MOJO_PUBLIC_CPP_BINDINGS_LIB_FIXED_BUFFER_H_ | |
| 6 #define MOJO_PUBLIC_CPP_BINDINGS_LIB_FIXED_BUFFER_H_ | |
| 7 | |
| 8 #include "mojo/public/cpp/bindings/lib/buffer.h" | |
| 9 #include "mojo/public/cpp/system/macros.h" | |
| 10 | |
| 11 namespace mojo { | |
| 12 namespace internal { | |
| 13 | |
| 14 // FixedBuffer provides a simple way to allocate objects within a fixed chunk | |
| 15 // of memory. Objects are allocated by calling the |Allocate| method, which | |
| 16 // extends the buffer accordingly. Objects allocated in this way are not freed | |
| 17 // explicitly. Instead, they remain valid so long as the FixedBuffer remains | |
| 18 // valid. The Leak method may be used to steal the underlying memory from the | |
| 19 // FixedBuffer. | |
| 20 // | |
| 21 // Typical usage: | |
| 22 // | |
| 23 // { | |
| 24 // FixedBuffer buf(8 + 8); | |
| 25 // | |
| 26 // int* a = static_cast<int*>(buf->Allocate(sizeof(int))); | |
| 27 // *a = 2; | |
| 28 // | |
| 29 // double* b = static_cast<double*>(buf->Allocate(sizeof(double))); | |
| 30 // *b = 3.14f; | |
| 31 // | |
| 32 // void* data = buf.Leak(); | |
| 33 // Process(data); | |
| 34 // | |
| 35 // free(data); | |
| 36 // } | |
| 37 // | |
| 38 class FixedBuffer : public Buffer { | |
| 39 public: | |
| 40 explicit FixedBuffer(size_t size); | |
| 41 ~FixedBuffer() override; | |
| 42 | |
| 43 // Grows the buffer by |num_bytes| and returns a pointer to the start of the | |
| 44 // addition. The resulting address is 8-byte aligned, and the content of the | |
| 45 // memory is zero-filled. | |
| 46 void* Allocate(size_t num_bytes) override; | |
| 47 | |
| 48 size_t size() const { return size_; } | |
| 49 | |
| 50 // Returns the internal memory owned by the Buffer to the caller. The Buffer | |
| 51 // relinquishes its pointer, effectively resetting the state of the Buffer | |
| 52 // and leaving the caller responsible for freeing the returned memory address | |
| 53 // when no longer needed. | |
| 54 void* Leak(); | |
| 55 | |
| 56 private: | |
| 57 char* ptr_; | |
| 58 size_t cursor_; | |
| 59 size_t size_; | |
| 60 | |
| 61 MOJO_DISALLOW_COPY_AND_ASSIGN(FixedBuffer); | |
| 62 }; | |
| 63 | |
| 64 } // namespace internal | |
| 65 } // namespace mojo | |
| 66 | |
| 67 #endif // MOJO_PUBLIC_CPP_BINDINGS_LIB_FIXED_BUFFER_H_ | |
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