mukesh agrawal | 3d8db08 | 2016-09-30 18:47:12 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2016 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | #ifndef BYTE_BUFFER_H_ |
| 18 | #define BYTE_BUFFER_H_ |
| 19 | |
| 20 | #include <array> |
| 21 | #include <cstring> |
| 22 | |
| 23 | #include "android-base/logging.h" |
| 24 | |
| 25 | #include "wifilogd/local_utils.h" |
| 26 | |
| 27 | namespace android { |
| 28 | namespace wifilogd { |
| 29 | |
| 30 | // A fixed-size buffer, which provides the ability to accumulate bytes. |
| 31 | // The buffer tracks its (populated) size, and does not require dynamic |
| 32 | // memory allocation. |
| 33 | // |
mukesh agrawal | 937164d | 2016-10-20 15:35:26 -0700 | [diff] [blame] | 34 | // Usage could be as follows: |
xshu | 31aa7aa | 2017-09-29 14:05:32 -0700 | [diff] [blame] | 35 | // const auto buffer = ByteBuffer<1024>() |
mukesh agrawal | 937164d | 2016-10-20 15:35:26 -0700 | [diff] [blame] | 36 | // .AppendOrDie(header.data(), header.size()) |
| 37 | // .AppendOrDie(body.data(), body.size()); |
mukesh agrawal | 3d8db08 | 2016-09-30 18:47:12 -0700 | [diff] [blame] | 38 | // write(fd, buffer.data(), buffer.size()); |
| 39 | template <size_t SizeBytes> |
| 40 | class ByteBuffer { |
| 41 | public: |
| 42 | ByteBuffer() : write_pos_(0) {} |
| 43 | |
| 44 | // Appends data to the end of this buffer. Aborts if the available |
mukesh agrawal | 937164d | 2016-10-20 15:35:26 -0700 | [diff] [blame] | 45 | // space in the buffer is less than |data_len|. Returns a reference to |
| 46 | // the ByteBuffer, to support chaining. |
| 47 | ByteBuffer<SizeBytes>& AppendOrDie(NONNULL const void* data, |
| 48 | size_t data_len) { |
mukesh agrawal | 3d8db08 | 2016-09-30 18:47:12 -0700 | [diff] [blame] | 49 | CHECK(data_len <= raw_buffer_.size() - write_pos_); |
| 50 | std::memcpy(raw_buffer_.data() + write_pos_, data, data_len); |
| 51 | write_pos_ += data_len; |
mukesh agrawal | 937164d | 2016-10-20 15:35:26 -0700 | [diff] [blame] | 52 | return *this; |
mukesh agrawal | 3d8db08 | 2016-09-30 18:47:12 -0700 | [diff] [blame] | 53 | } |
| 54 | |
| 55 | // Returns a pointer to the head of this buffer. |
| 56 | RETURNS_NONNULL const uint8_t* data() const { return raw_buffer_.data(); } |
| 57 | |
| 58 | // Returns the number of bytes written to this buffer. |
| 59 | size_t size() const { return write_pos_; } |
| 60 | |
| 61 | private: |
| 62 | std::array<uint8_t, SizeBytes> raw_buffer_; |
| 63 | size_t write_pos_; |
| 64 | }; |
| 65 | |
| 66 | } // namespace wifilogd |
| 67 | } // namespace android |
| 68 | #endif // BYTE_BUFFER_H_ |