HTcell.cc

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#include "L1Trigger/TrackFindingTMTT/interface/HTcell.h"
#include "L1Trigger/TrackFindingTMTT/interface/TP.h"
#include "L1Trigger/TrackFindingTMTT/interface/Stub.h"

using namespace std;

namespace tmtt {

  //=== Initialization with cfg params,
  //=== rapidity range of current sector, and estimated q/Pt of cell,
  //=== and the bin number of the cell along the q/Pt axis of the r-phi HT array,
  //=== and a flag indicating if this cell is the merge of smaller HT cells.

  HTcell::HTcell(const Settings* settings,
                 unsigned int iPhiSec,
                 unsigned int iEtaReg,
                 float etaMinSector,
                 float etaMaxSector,
                 float qOverPt,
                 unsigned int ibin_qOverPt,
                 bool mergedCell,
                 bool miniHTcell)
      : settings_(settings),
        // Sector number
        iPhiSec_(iPhiSec),
        iEtaReg_(iEtaReg),
        // Rapidity range of sector.
        etaMinSector_(etaMinSector),
        etaMaxSector_(etaMaxSector),
        // Track q/Pt.
        qOverPtCell_(qOverPt),
        // Note bin number of cell along q/Pt axis of r-phi HT array. (Not used if r-z HT).
        ibin_qOverPt_(ibin_qOverPt),
        mergedCell_(mergedCell),
        // Is cell in Mini-HT?
        miniHTcell_(miniHTcell),
        invPtToDphi_(settings->invPtToDphi()),  // B*c/2E11
        // Use filter in each HT cell using only stubs which have consistent bend?
        useBendFilter_(settings->useBendFilter()),
        // Check if subsectors are being used within each sector. These are only ever used for r-phi HT.
        numSubSecs_(settings->numSubSecsEta()) {
    // A filter is used each HT cell, which prevents more than the specified number of stubs being stored in the cell. (Reflecting memory limit of hardware).
    if (miniHTcell_) {
      maxStubsInCell_ = settings->maxStubsInCellMiniHough();
    } else {
      maxStubsInCell_ = settings->maxStubsInCell();
    }
  }

  //=== Termination. Search for track in this HT cell etc.

  void HTcell::end() {
    // Produce list of filtered stubs by applying all requested filters (e.g. on stub bend).
    // (If no filters are requested, then filtered & unfiltered stub collections will be identical).

    // N.B. Other filters,  such as the r-z filters, which the firmware runs after the HT because they are too slow within it,
    // are not defined here, but instead inside class TrkFilterAfterRphiHT.

    vFilteredStubs_ = vStubs_;
    if (useBendFilter_)
      vFilteredStubs_ = this->bendFilter(vFilteredStubs_);

    // Prevent too many stubs being stored in a single HT cell if requested (to reflect hardware memory limits).
    // N.B. This MUST be the last filter applied.
    constexpr unsigned int disableThreshold = 999;
    if (maxStubsInCell_ < disableThreshold)
      vFilteredStubs_ = this->maxStubCountFilter(vFilteredStubs_);

    // Calculate the number of layers the filtered stubs in this cell are in.
    numFilteredLayersInCell_ = this->calcNumFilteredLayers();

    if (numSubSecs_ > 1) {
      // If using subsectors within each sector, calculate the number of layers the filters stubs in this cell are in,
      // when one considers only the subset of the stubs within each subsector.
      // Look for the "best" subsector.
      numFilteredLayersInCellBestSubSec_ = 0;
      for (unsigned int i = 0; i < numSubSecs_; i++) {
        unsigned int numLaySubSec = this->calcNumFilteredLayers(i);
        numFilteredLayersInCellBestSubSec_ = max(numFilteredLayersInCellBestSubSec_, numLaySubSec);
      }
    } else {
      // If only 1 sub-sector, then subsector and sector are identical.
      numFilteredLayersInCellBestSubSec_ = numFilteredLayersInCell_;
    }
  }

  // Calculate how many tracker layers the filter stubs in this cell are in, when only the subset of those stubs
  // that are in the specified subsector are counted.

  unsigned int HTcell::calcNumFilteredLayers(unsigned int iSubSec) const {
    vector<const Stub*> stubsInSubSec;
    for (const Stub* s : vFilteredStubs_) {
      const vector<bool>& inSubSec = subSectors_.at(s);  // Find out which subsectors this stub is in.
      if (inSubSec[iSubSec])
        stubsInSubSec.push_back(s);
    }
    return Utility::countLayers(settings_, stubsInSubSec);
  }

  //=== Produce a filtered collection of stubs in this cell that all have consistent bend.
  //=== Only called for r-phi Hough transform.

  vector<Stub*> HTcell::bendFilter(const vector<Stub*>& stubs) const {
    // Create bend-filtered stub collection.
    vector<Stub*> filteredStubs;
    for (Stub* s : stubs) {
      // Require stub bend to be consistent with q/Pt of this cell.

      unsigned int minBin = s->min_qOverPt_bin();
      unsigned int maxBin = s->max_qOverPt_bin();
      if (mergedCell_) {
        if (minBin % 2 == 1)
          minBin--;
      }
      if (minBin <= ibin_qOverPt_ && ibin_qOverPt_ <= maxBin)
        filteredStubs.push_back(s);
    }

    return filteredStubs;
  }

  //=== Filter stubs so as to prevent more than specified number of stubs being stored in one cell.
  //=== This reflects finite memory of hardware.

  vector<Stub*> HTcell::maxStubCountFilter(const vector<Stub*>& stubs) const {
    vector<Stub*> filteredStubs;
    // If there are too many stubs in a cell, the hardware keeps (maxStubsInCell - 1) of the first stubs in the list
    // plus the last stub.
    if (stubs.size() > maxStubsInCell_) {
      for (unsigned int i = 0; i < maxStubsInCell_ - 1; i++) {  // first stubs
        filteredStubs.push_back(stubs[i]);
      }
      filteredStubs.push_back(stubs[stubs.size() - 1]);  // plus last stub
    } else {
      filteredStubs = stubs;
    }
    return filteredStubs;
  }

}  // namespace tmtt