text: /*
   *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
   *
   *  Use of this source code is governed by a BSD-style license
   *  that can be found in the LICENSE file in the root of the source
   *  tree. An additional intellectual property rights grant can be found
   *  in the file PATENTS.  All contributing project authors may
   *  be found in the AUTHORS file in the root of the source tree.
   */
  
  #ifndef MODULES_AUDIO_CODING_NETEQ_PACKET_H_
  #define MODULES_AUDIO_CODING_NETEQ_PACKET_H_
  
  #include <stdint.h>
  #include <list>
  #include <memory>
  
  #include "api/audio_codecs/audio_decoder.h"
  #include "modules/audio_coding/neteq/tick_timer.h"
  #include "rtc_base/buffer.h"
  #include "rtc_base/checks.h"
  
  namespace webrtc {
  
  // Struct for holding RTP packets.
  struct Packet {
    struct Priority {
      Priority() : codec_level(0), red_level(0) {}
      Priority(int codec_level, int red_level)
          : codec_level(codec_level), red_level(red_level) {
        CheckInvariant();
      }
  
      int codec_level;
      int red_level;
  
      // Priorities are sorted low-to-high, first on the level the codec
      // prioritizes it, then on the level of RED packet it is; i.e. if it is a
      // primary or secondary payload of a RED packet. For example: with Opus, an
      // Fec packet (which the decoder prioritizes lower than a regular packet)
      // will not be used if there is _any_ RED payload for the same
      // timeframe. The highest priority packet will have levels {0, 0}. Negative
      // priorities are not allowed.
      bool operator<(const Priority& b) const {
        CheckInvariant();
        b.CheckInvariant();
        if (codec_level == b.codec_level)
          return red_level < b.red_level;
  
        return codec_level < b.codec_level;
      }
      bool operator==(const Priority& b) const {
        CheckInvariant();
        b.CheckInvariant();
        return codec_level == b.codec_level && red_level == b.red_level;
      }
      bool operator!=(const Priority& b) const { return !(*this == b); }
      bool operator>(const Priority& b) const { return b < *this; }
      bool operator<=(const Priority& b) const { return !(b > *this); }
      bool operator>=(const Priority& b) const { return !(b < *this); }
  
     private:
      void CheckInvariant() const {
        RTC_DCHECK_GE(codec_level, 0);
        RTC_DCHECK_GE(red_level, 0);
      }
    };
  
    uint32_t timestamp;
    uint16_t sequence_number;
    uint8_t payload_type;
    // Datagram excluding RTP header and header extension.
    rtc::Buffer payload;
    Priority priority;
    std::unique_ptr<TickTimer::Stopwatch> waiting_time;
    std::unique_ptr<AudioDecoder::EncodedAudioFrame> frame;
  
    Packet();
    Packet(Packet&& b);
    ~Packet();
  
    // Packets should generally be moved around but sometimes it's useful to make
    // a copy, for example for testing purposes. NOTE: Will only work for
    // un-parsed packets, i.e. |frame| must be unset. The payload will, however,
    // be copied. |waiting_time| will also not be copied.
    Packet Clone() const;
  
    Packet& operator=(Packet&& b);
  
    // Comparison operators. Establish a packet ordering based on (1) timestamp,
    // (2) sequence number and (3) redundancy.
    // Timestamp and sequence numbers are compared taking wrap-around into
    // account. For two packets with the same sequence number and timestamp a
    // primary payload is considered "smaller" than a secondary.
    bool operator==(const Packet& rhs) const {
      return (this->timestamp == rhs.timestamp &&
              this->sequence_number == rhs.sequence_number &&
              this->priority == rhs.priority);
    }
    bool operator!=(const Packet& rhs) const { return !operator==(rhs); }
    bool operator<(const Packet& rhs) const {
      if (this->timestamp == rhs.timestamp) {
        if (this->sequence_number == rhs.sequence_number) {
          // Timestamp and sequence numbers are identical - deem the left hand
          // side to be "smaller" (i.e., "earlier") if it has higher priority.
          return this->priority < rhs.priority;
        }
        return (static_cast<uint16_t>(rhs.sequence_number -
                                      this->sequence_number) < 0xFFFF / 2);
      }
      return (static_cast<uint32_t>(rhs.timestamp - this->timestamp) <
              0xFFFFFFFF / 2);
    }
    bool operator>(const Packet& rhs) const { return rhs.operator<(*this); }
    bool operator<=(const Packet& rhs) const { return !operator>(rhs); }
    bool operator>=(const Packet& rhs) const { return !operator<(rhs); }
  
    bool empty() const { return !frame && payload.empty(); }
  };
  
  // A list of packets.
  typedef std::list<Packet> PacketList;
  
  }  // namespace webrtc
  #endif  // MODULES_AUDIO_CODING_NETEQ_PACKET_H_
  