TRT_LoLumRawData.cxx

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/*
  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
*/
 
 
 
// TRT_LoLumRawData.cxx
//   Implementation file for class TRT_LoLumRawData
// (c) ATLAS Detector software
// Version 1.0 13/08/2002 Veronique Boisvert
// Implementation provided by A. Zalite, February 2003
 
#include "InDetRawData/TRT_LoLumRawData.h"
#include "InDetRawData/TRT_RDORawData.h"
 
 
 
// default constructor
TRT_LoLumRawData::TRT_LoLumRawData() :
  TRT_RDORawData(Identifier(), 0) //call base-class constructor
{}
 
// Constructor with parameters:
TRT_LoLumRawData::TRT_LoLumRawData(const Identifier rdoId,
                           const unsigned int word) :
  TRT_RDORawData( rdoId, word) //call base-class constructor
{}
 
void TRT_LoLumRawData::findLargestIsland(unsigned int word, Island& island) {
  unsigned long mask = 0x02000000;  // 0 0 10000000 0 00000000 0 00000000
  unsigned int bestLength = 0;
  unsigned int currentLength = 0;
 
  // set 4 last bits to zero (to match data and MC bitmasks)
  unsigned int wordLE = word & m_maskFourLastBits;
 
  mask >>=1;  // 0 0 01000000 0 00000000 0 00000000
  bool SawZero = false;
  unsigned int k = 1;
  island.m_leadingEdge=0, island.m_trailingEdge=0;
  unsigned int currentLeadingEdge=0, currentTrailingEdge=0;
 
  // shift bitmask to the right until end
  while (true) {
    if (!(wordLE & mask) && !SawZero) SawZero = true; // search for the first 0 to 1 transition
    if (SawZero) {
      if (wordLE & mask){
        if (currentLength==0) currentLeadingEdge=k;
        currentTrailingEdge=k;
        ++currentLength;
      } else { // remember longest island, ignore islands of length 1 which are very likely noise
        if (currentLength >= bestLength && currentLeadingEdge<18 && currentLength > 1) {
          bestLength = currentLength;
          island.m_leadingEdge = currentLeadingEdge;
          island.m_trailingEdge = currentTrailingEdge;
        }
        currentLength = 0;
      }
    }
    mask >>= 1;
    if (!(mask & m_maskThreeLastBits)) break; // stop after checking 20 LT bits
    if (k == 7 || k == 15) mask >>= 1; // ignore HT bits
    assert(k < 20);
    ++k;
  }
  assert(k == 20);
  // avoid very early TE, most likely from previous BX. Hit will still be used for tracking if it has a valid LE
  if (island.m_trailingEdge < 8) island.m_trailingEdge = 0;
}