ELinkDecoder.h

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// Copyright 2019-2020 CERN and copyright holders of ALICE O2.
// See https://alice-o2.web.cern.ch/copyright for details of the copyright holders.
// All rights not expressly granted are reserved.
//
// This software is distributed under the terms of the GNU General Public
// License v3 (GPL Version 3), copied verbatim in the file "COPYING".
//
// In applying this license CERN does not waive the privileges and immunities
// granted to it by virtue of its status as an Intergovernmental Organization
// or submit itself to any jurisdiction.
 
#ifndef O2_MID_ELINKDECODER_H
#define O2_MID_ELINKDECODER_H
 
#include <cstdint>
#include <vector>
#include <gsl/gsl>
 
#include "DataFormatsMID/ROBoard.h"
 
namespace o2
{
namespace mid
{
class ELinkDecoder
{
 public:
  void setBareDecoder(bool isBare);
  inline void add(const uint8_t byte) { mBytes.emplace_back(byte); }
  void addAndComputeSize(const uint8_t byte);
  template <class ITERATOR>
  bool addCore(ITERATOR& it, const ITERATOR& end)
  {
    auto remaining = mMinimumSize - mBytes.size();
    return add(it, end, remaining);
  }
  template <class ITERATOR>
  bool add(ITERATOR& it, const ITERATOR& end)
  {
    auto remaining = mTotalSize - mBytes.size();
    if (add(it, end, remaining)) {
      if (mTotalSize == mMinimumSize) {
        computeSize();
        remaining = mTotalSize - mBytes.size();
        if (remaining) {
          return add(it, end, remaining);
        }
      }
      return true;
    }
    return false;
  }
 
  inline bool addCore(size_t& idx, gsl::span<const uint8_t> payload, size_t step) { return add(idx, payload, mMinimumSize - mBytes.size(), step); }
 
  bool add(size_t& idx, gsl::span<const uint8_t> payload, size_t step);
 
  inline bool isZero(uint8_t byte) const { return (mBytes.empty() && (byte & raw::sSTARTBIT) == 0); }
 
  inline bool isComplete() const { return mBytes.size() == mTotalSize; };
  inline uint8_t getStatusWord() const { return mBytes[0]; }
  inline uint8_t getTriggerWord() const { return mBytes[1]; }
  inline uint16_t getCounter() const { return joinBytes(2); }
  inline uint8_t getId() const { return (mBytes[4] >> 4) & 0xF; }
  inline uint8_t getInputs() const { return (mBytes[4] & 0xF); }
  inline uint8_t getCrateId() const { return (mBytes[5] >> 4) & 0xF; }
  uint16_t getPattern(int cathode, int chamber) const;
  inline size_t getNBytes() const { return mBytes.size(); }
 
  void reset();
 
 private:
  inline uint16_t joinBytes(int idx) const { return (mBytes[idx] << 8 | mBytes[idx + 1]); };
  template <class ITERATOR>
  bool add(ITERATOR& it, const ITERATOR& end, size_t nBytes)
  {
    auto nToEnd = std::distance(it, end);
    auto nAdded = nBytes < nToEnd ? nBytes : nToEnd;
    mBytes.insert(mBytes.end(), it, it + nAdded);
    it += nAdded;
    return (nAdded == nBytes);
  }
 
  bool add(size_t& idx, gsl::span<const uint8_t> payload, size_t nBytes, size_t step);
 
  void computeSize();
 
  size_t mMinimumSize{5};          
  size_t mMaximumSize{21};         
  std::vector<uint8_t> mBytes{};   
  size_t mTotalSize{mMinimumSize}; 
};
} // namespace mid
} // namespace o2
 
#endif /* O2_MID_ELINKDECODER_H */