ELinkDecoder.cxx

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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.
 
 
#include "MIDRaw/ELinkDecoder.h"
 
namespace o2
{
namespace mid
{
 
void ELinkDecoder::setBareDecoder(bool isBare)
{
  mMinimumSize = isBare ? 5 : 6;
  mMaximumSize = isBare ? 21 : 22;
  mTotalSize = mMinimumSize;
}
 
bool ELinkDecoder::add(size_t& idx, gsl::span<const uint8_t> payload, size_t nBytes, size_t step)
{
  auto size = payload.size();
  auto end = idx + step * nBytes;
  if (size < end) {
    end = size;
  }
  size_t nAdded = 0;
  for (; idx < end; idx += step) {
    mBytes.emplace_back(payload[idx]);
    ++nAdded;
  }
  return (nAdded == nBytes);
}
 
bool ELinkDecoder::add(size_t& idx, gsl::span<const uint8_t> payload, size_t step)
{
  auto remaining = mTotalSize - mBytes.size();
  if (add(idx, payload, remaining, step)) {
    if (mTotalSize == mMinimumSize) {
      computeSize();
      remaining = mTotalSize - mBytes.size();
      if (remaining) {
        return add(idx, payload, remaining, step);
      }
    }
    return true;
  }
  return false;
}
 
void ELinkDecoder::addAndComputeSize(uint8_t byte)
{
  mBytes.emplace_back(byte);
  if (mBytes.size() == mMinimumSize) {
    computeSize();
  }
}
 
void ELinkDecoder::computeSize()
{
  if (raw::isLoc(mBytes[0])) {
    // This is a local card
    uint8_t mask = getInputs();
    for (int ich = 0; ich < 4; ++ich) {
      if ((mask >> ich) & 0x1) {
        // We expect 2 bytes for the BP and 2 for the NBP
        mTotalSize += 4;
      }
    }
  }
}
 
void ELinkDecoder::reset()
{
  mBytes.clear();
  mTotalSize = mMinimumSize;
}
 
uint16_t ELinkDecoder::getPattern(int cathode, int chamber) const
{
  uint8_t mask = getInputs();
  if (((mask >> chamber) & 0x1) == 0) {
    return 0;
  }
 
  int idx = mBytes.size();
  for (int ich = 0; ich <= chamber; ++ich) {
    if ((mask >> ich) & 0x1) {
      idx -= 4;
    }
  }
 
  idx += 2 * cathode;
 
  return joinBytes(idx);
}
 
} // namespace mid
} // namespace o2