| // Copyright 2014 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef MOJO_PUBLIC_CPP_BINDINGS_LIB_FIXED_BUFFER_H_ |
| #define MOJO_PUBLIC_CPP_BINDINGS_LIB_FIXED_BUFFER_H_ |
| |
| #include "mojo/public/cpp/bindings/lib/buffer.h" |
| #include "mojo/public/cpp/system/macros.h" |
| |
| namespace mojo { |
| namespace internal { |
| |
| // FixedBuffer provides a simple way to allocate objects within a fixed chunk |
| // of memory. Objects are allocated by calling the |Allocate| method, which |
| // extends the buffer accordingly. Objects allocated in this way are not freed |
| // explicitly. Instead, they remain valid so long as the FixedBuffer remains |
| // valid. The Leak method may be used to steal the underlying memory from the |
| // FixedBuffer. |
| // |
| // Typical usage: |
| // |
| // { |
| // FixedBuffer buf(8 + 8); |
| // |
| // int* a = static_cast<int*>(buf->Allocate(sizeof(int))); |
| // *a = 2; |
| // |
| // double* b = static_cast<double*>(buf->Allocate(sizeof(double))); |
| // *b = 3.14f; |
| // |
| // void* data = buf.Leak(); |
| // Process(data); |
| // |
| // free(data); |
| // } |
| // |
| class FixedBuffer : public Buffer { |
| public: |
| explicit FixedBuffer(size_t size); |
| virtual ~FixedBuffer(); |
| |
| // Grows the buffer by |num_bytes| and returns a pointer to the start of the |
| // addition. The resulting address is 8-byte aligned, and the content of the |
| // memory is zero-filled. |
| virtual void* Allocate(size_t num_bytes) MOJO_OVERRIDE; |
| |
| size_t size() const { return size_; } |
| |
| // Returns the internal memory owned by the Buffer to the caller. The Buffer |
| // relinquishes its pointer, effectively resetting the state of the Buffer |
| // and leaving the caller responsible for freeing the returned memory address |
| // when no longer needed. |
| void* Leak(); |
| |
| private: |
| char* ptr_; |
| size_t cursor_; |
| size_t size_; |
| |
| MOJO_DISALLOW_COPY_AND_ASSIGN(FixedBuffer); |
| }; |
| |
| } // namespace internal |
| } // namespace mojo |
| |
| #endif // MOJO_PUBLIC_CPP_BINDINGS_LIB_FIXED_BUFFER_H_ |