/data/refman/pasoursint/CMSSW_6_1_2_SLHC4_patch1/src/SimCalorimetry/HcalSimAlgos/src/HcalTDC.cc

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#include "SimCalorimetry/HcalSimAlgos/interface/HcalTDC.h"
#include "CalibFormats/HcalObjects/interface/HcalCalibrations.h"
#include "CalibFormats/HcalObjects/interface/HcalDbService.h"

HcalTDC::HcalTDC() : theTDCParameters(), theDbService(0), theRandGaussQ(0) {}

HcalTDC::~HcalTDC() {
  if (theRandGaussQ) delete theRandGaussQ;
}

void HcalTDC::timing(const CaloSamples& lf, HcalUpgradeDataFrame& digi) const {

  float TDC_Threshold = getThreshold(digi.id());
  bool alreadyOn = false;
  int tdcBins = theTDCParameters.nbins();
  // start with a loop over 10 samples
  bool hasTDCValues=true;
  if (lf.preciseSize()==0 ) hasTDCValues=false;
  for (int ibin = 0; ibin < lf.size(); ++ibin) {
    /*
    If in a given 25ns bunch/time sample, the pulse is above TDC_Thresh  
    already, then TDC_RisingEdge=0
    if it was low in the last precision bin on the previous bunch crossing,
    otherwise, TDC_RisingEdge=tdcBins
    if the pulse never crosses the threshold having started off, then the special code is tdcBins+1
    and then one can still have a TDC_FallingEdge that is valid.  If  
    the pulse never falls below threshold having
    started above threshold (or goes above threshold in the bunch crossing and doesn't come down), 
    then TDC_FallingEdge=tdcBins+1.  If the pulse never  
    went above threshold, then
    TDC_RisingEdge=tdcBins+1 and TDC_FallingEdge=tdcBins.
    */
    // special codes
    int TDC_RisingEdge = alreadyOn ? tdcBins : tdcBins+1;
    int TDC_FallingEdge = alreadyOn ? tdcBins+1 : tdcBins;
    int preciseBegin = ibin * tdcBins;
    int preciseEnd = preciseBegin + tdcBins;
    if ( hasTDCValues) {
      for(int i = preciseBegin; i < preciseEnd; ++i) { 
        if (alreadyOn) {
          if(lf.preciseAt(i) < TDC_Threshold) {
            alreadyOn = false;
            TDC_FallingEdge = i-preciseBegin;
          }
        } else {
          if (lf.preciseAt(i) > TDC_Threshold) {
            alreadyOn = true;
            TDC_RisingEdge = i-preciseBegin;
            // the flag for hasn't gone low yet
            TDC_FallingEdge = tdcBins+1;
          }
        }
      }
    }
    // change packing to allow for special codes
    int packedTDC = TDC_RisingEdge + (tdcBins*2) * TDC_FallingEdge;
    digi.setSample(ibin, digi.adc(ibin), packedTDC, true);
  } // loop over bunch crossing bins
}

double HcalTDC::getThreshold(const HcalGenericDetId & detId) const {
  // subtract off pedestal and noise once
  double pedestal = theDbService->getHcalCalibrations(detId).pedestal(0);
  double pedestalWidth = theDbService->getHcalCalibrationWidths(detId).pedestal(0);
  // here the TDCthreshold_ is a fixed parameter = 100 fC on the absolute QIE10 scale before pedestal subtraction
  // the pedestal width is injecting noise - no hysterysis is being simulated here
  return 100. - theRandGaussQ->shoot(pedestal,  pedestalWidth);
}

void HcalTDC::setRandomEngine(CLHEP::HepRandomEngine & engine) {
  theRandGaussQ = new CLHEP::RandGaussQ(engine);
}

void HcalTDC::setDbService(const HcalDbService * service) {
  theDbService = service;
}