SkippableFrame.h

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/*
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 * All rights reserved.
 *
 * This source code is licensed under both the BSD-style license (found in the
 * LICENSE file in the root directory of this source tree) and the GPLv2 (found
 * in the COPYING file in the root directory of this source tree).
 */
#pragma once
 
#include "utils/Range.h"
 
#include <array>
#include <cstddef>
#include <cstdint>
#include <cstdio>
 
namespace pzstd {
class SkippableFrame {
 public:
  static constexpr std::size_t kSize = 12;
 
 private:
  std::uint32_t frameSize_;
  std::array<std::uint8_t, kSize> data_;
  static constexpr std::uint32_t kSkippableFrameMagicNumber = 0x184D2A50;
  // Could be improved if the size fits in less bytes
  static constexpr std::uint32_t kFrameContentsSize = kSize - 8;
 
 public:
   // Write the skippable frame to data_ in LE format.
  explicit SkippableFrame(std::uint32_t size);
 
  // Read the skippable frame from bytes in LE format.
  static std::size_t tryRead(ByteRange bytes);
 
  ByteRange data() const {
    return {data_.data(), data_.size()};
  }
 
  // Size of the next frame.
  std::size_t frameSize() const {
    return frameSize_;
  }
};
}