68 lines
2.1 KiB
C++
68 lines
2.1 KiB
C++
/*
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* Copyright (C) 2016 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef BYTE_BUFFER_H_
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#define BYTE_BUFFER_H_
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#include <array>
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#include <cstring>
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#include "android-base/logging.h"
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#include "wifilogd/local_utils.h"
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namespace android {
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namespace wifilogd {
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// A fixed-size buffer, which provides the ability to accumulate bytes.
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// The buffer tracks its (populated) size, and does not require dynamic
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// memory allocation.
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//
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// Usage could be as follows:
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// const auto& buffer = ByteBuffer<1024>()
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// .AppendOrDie(header.data(), header.size())
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// .AppendOrDie(body.data(), body.size());
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// write(fd, buffer.data(), buffer.size());
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template <size_t SizeBytes>
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class ByteBuffer {
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public:
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ByteBuffer() : write_pos_(0) {}
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// Appends data to the end of this buffer. Aborts if the available
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// space in the buffer is less than |data_len|. Returns a reference to
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// the ByteBuffer, to support chaining.
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ByteBuffer<SizeBytes>& AppendOrDie(NONNULL const void* data,
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size_t data_len) {
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CHECK(data_len <= raw_buffer_.size() - write_pos_);
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std::memcpy(raw_buffer_.data() + write_pos_, data, data_len);
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write_pos_ += data_len;
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return *this;
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}
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// Returns a pointer to the head of this buffer.
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RETURNS_NONNULL const uint8_t* data() const { return raw_buffer_.data(); }
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// Returns the number of bytes written to this buffer.
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size_t size() const { return write_pos_; }
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private:
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std::array<uint8_t, SizeBytes> raw_buffer_;
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size_t write_pos_;
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};
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} // namespace wifilogd
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} // namespace android
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#endif // BYTE_BUFFER_H_
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