FPGATrackSimHough1DShiftTool.cxx

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// Copyright (C) 2002-2025 CERN for the benefit of the ATLAS collaboration

 
#include "FPGATrackSimObjects/FPGATrackSimTypes.h"
#include "FPGATrackSimObjects/FPGATrackSimConstants.h"
#include "FPGATrackSimObjects/FPGATrackSimHit.h"
#include "FPGATrackSimConfTools/FPGATrackSimRegionSlices.h"
#include "FPGATrackSimConfTools/IFPGATrackSimEventSelectionSvc.h"
#include "FPGATrackSimMaps/IFPGATrackSimMappingSvc.h"
#include "FPGATrackSimMaps/FPGATrackSimPlaneMap.h"
#include "FPGATrackSimMaps/FPGATrackSimRegionMap.h"
#include "FPGATrackSimBanks/IFPGATrackSimBankSvc.h"
#include "FPGATrackSimBanks/FPGATrackSimSectorBank.h"
#include "FPGATrackSimHoughTransformTool.h"
#include "FPGATrackSimHough1DShiftTool.h"
#include "TH2.h"
 
#include <sstream>
#include <cmath>
#include <algorithm>
#include <boost/dynamic_bitset.hpp>
#include <iostream>
 
static inline std::string to_string(std::vector<size_t> v);
static inline boost::dynamic_bitset<> lshift(boost::dynamic_bitset<> const & b, int n);
static inline boost::dynamic_bitset<> rshift(boost::dynamic_bitset<> const & b, int n);
static inline void updateBinHits(std::vector<boost::dynamic_bitset<>> & binHits, unsigned layer, boost::dynamic_bitset<> const & b);
static inline int layersHit(FPGATrackSimRoad& r);
 
 
StatusCode FPGATrackSimHough1DShiftTool::initialize()
{
    // Config printout
    ATH_MSG_INFO("Phi range: (" << m_phiMin << "," << m_phiMax << "," << m_phiBins << ")");
    if (m_useDiff) ATH_MSG_INFO("useDiff Set True");
    if (m_variableExtend) ATH_MSG_INFO("variableExtend Set True");
    ATH_MSG_INFO("enhancedHighPt " << m_enhanceHighPt.value());
    ATH_MSG_INFO("applyDropable " << m_applyDropable.value());
    ATH_MSG_INFO("threshold " << m_threshold.value());
    
    // Retrieve info
    if (m_idealGeoRoads || m_useSectors) ATH_CHECK(m_FPGATrackSimBankSvc.retrieve());
    ATH_CHECK(m_FPGATrackSimMapping.retrieve());
    m_nLayers = m_FPGATrackSimMapping->PlaneMap_1st(0)->getNLogiLayers();
 
    // Error checking
    if (m_phiMin >= m_phiMax || m_phiBins == 0u) {
        ATH_MSG_FATAL("initialize() Phi range invalid");
    return StatusCode::FAILURE;
    }
 
    // Fix inputs
    if (!m_hitExtendProperty.value().empty()) {
      if (m_hitExtendProperty.value().size() != m_nLayers) {
    ATH_MSG_FATAL("initialize() Hit extend must have size == nLayers");
    return StatusCode::FAILURE;
      } else {
    m_hitExtend = m_hitExtendProperty.value();
      }
    } else {
      m_hitExtend.resize(m_nLayers,0); // all 0
    }
    if (m_iterStep == 0u) m_iterStep = m_hitExtend[m_iterLayer] * 2 + 1; // default 1
 
    // Copy correct r values from the region map.
    m_r.resize(m_nLayers);
    for (unsigned ilayer = 0; ilayer < m_nLayers; ilayer++) {
        m_r[ilayer] = m_FPGATrackSimMapping->SubRegionMap()->getAvgRadius(m_subRegion, ilayer);
    }
 
    // Warnings / corrections
     if (m_idealGeoRoads)
    {
        if (m_useSectors)
        {
            ATH_MSG_WARNING("initialize() idealGeoRoads conflicts with useSectors, switching off FPGATrackSim sector matching");
            m_useSectors = false;
        }
        if (!m_traceHits)
        {
            ATH_MSG_WARNING("initialize() idealGeoRoads requires tracing hits, turning on automatically");
            m_traceHits = true;
        }
    }
 
    // Fill convenience variables
    m_phiStep = (m_phiMax - m_phiMin) / m_phiBins;
    for (unsigned i = 0; i <= m_phiBins; i++)
        m_bins.push_back(m_phiMin + m_phiStep * i);
    m_regionMin = m_EvtSel->getRegions()->getMin(m_EvtSel->getRegionID());
    m_regionMax = m_EvtSel->getRegions()->getMax(m_EvtSel->getRegionID());
 
    m_regionMin.phi = m_regionMin.phi - 0.01; // For phi boundary effect   
    m_regionMax.phi = m_regionMax.phi + 0.01; // For phi boundary effect 
 
    m_currentcounts.resize(m_phiBins);
 
    // Calculate the shift amounts
    if (m_bitShift_path.value().empty()) calculateShifts();
    else readShifts(m_bitShift_path);
    printShifts();
 
 
    return StatusCode::SUCCESS;
}
 
 
// Fills m_shifts
void FPGATrackSimHough1DShiftTool::calculateShifts()
{
    // Calculated d0shift if selected
    if (m_d0spread>0) calculated0Shifts();
 
 
    // Iterate over a steps of m_iterStep bin shift in m_iterLayer
    for (int sign = -1; sign<2; sign+=2) {
 
    // start at highest pT
    float iterShift = (sign>0) ? 0.0 : -1.0; // don't double count zero
 
    while (true)
    {
        float qpt = qPt(m_r[m_iterLayer], m_phiStep * iterShift);
        if (abs(qpt)>std::max(abs(m_qptMin),abs(m_qptMax))) break;
 
        if ((qpt <= m_qptMax ) && (qpt >= m_qptMin )) {
 
        std::vector<int> shifts; // Fill both +iterShift and -iterShift here
        for (unsigned i = 0; i < m_nLayers; i++)
        {
            float dPhi = deltaPhi(m_r[i], qpt);
            if (m_useDiff){
            dPhi -= deltaPhi(m_r[0], qpt);
            }
 
            int shift = static_cast<int>(round(dPhi / m_phiStep));
            if (shift >= static_cast<int>(m_phiBins) || shift <= -(static_cast<int>(m_phiBins))) return;
            shifts.push_back(shift);
        }
 
        // if thre are d0shifts, apply them
        for (const std::vector<int>& d0shift: m_d0shifts){
            m_shifts.push_back(applyVariation(shifts,d0shift,1));
            m_shifts.push_back(applyVariation(shifts,d0shift,-1));
        }
 
        m_qpt.push_back(qpt);
        m_shifts.push_back(std::move(shifts));
 
        }
 
        // smaller steps if in "enhanceHighPt" range
        iterShift += ((std::abs(qpt)>m_enhanceHighPt) ?  sign*float(m_iterStep): sign*float(m_iterStep)/2.0) ;
    }
    ATH_MSG_INFO("Ending shift, qpt("<< m_qptMin << ", " << m_qptMax <<") sign:" <<  sign << " shift:" << iterShift);
 
 
    // figure out which patterns are the same after dropping a hit
    calculateDropable();
    }
 
}
 
 
// Fills m_shifts
//
// This reads a bitshift pattern file, which is a simple space-separated text file
// where each row respresents one shift set / pattern. Each row contains
// (nLayers - 1) columns representing the shifts in layers [1, nLayers)
// (implicit 0 shift in layer 0), followed by a column that is a 'droplist'.
// The droplist is a string of 0s and 1s indicating which layers can be dropped
// for 4/5 matching, i.e (layer 0 is right-most bit).
//
// See /eos/atlas/atlascerngroupdisk/det-htt/sectors_constants/BitShiftHoughPatterns/2021-02-20/
void FPGATrackSimHough1DShiftTool::readShifts(std::string const & filepath)
{
    // Open the file
    std::ifstream fin(filepath);
    if (!fin.is_open())
    {
        ATH_MSG_FATAL("Couldn't open " << filepath);
        throw ("FPGATrackSimHough1DShiftTool::readShifts couldn't open " + filepath);
    }
 
    // Variables to fill
    std::string line;
    bool ok = true;
    int subregion = -1;
    bool newsubr = false;
    bool headerdone = false;
    int nslices = 0;
    int nphi=0;
 
 
    // Parse the file
    while (getline(fin, line))
    {
    newsubr|=(line.empty());
        if (line.empty() || line[0] == '#') continue;
        std::istringstream sline(line);
    if (!headerdone) {
        std::string towers, phi;
        ok = ok && (sline >> towers);
        if (towers!="towers") {
        ATH_MSG_FATAL("Parse Error expected 'towers' got "<< towers);
        throw ("FPGATrackSimHough1DShiftTool::readShifts couldn't parse " + filepath);
        }
        ok = ok && (sline >> nslices);
        ATH_MSG_INFO("FPGATrackSimHough1DShiftTool::readShifts " << nslices << "slices in shift file");
        ok = ok && (sline >> phi);
        if (phi!="phi") {
        ATH_MSG_FATAL("Parse Error expected 'phi' got "<< phi);
        throw ("FPGATrackSimHough1DShiftTool::readShifts couldn't parse " + filepath);
        }
        ok = ok && (sline >> nphi);
        headerdone=true;
        continue;
    }
 
    if (newsubr) {
        ok = ok && (sline >> subregion);
        ATH_MSG_INFO("FPGATrackSimHough1DShiftTool::readShifts " << subregion << " looking for " << m_subRegion);
        newsubr=false;
        continue;
    }
 
    if (subregion==m_subRegion) {
        ATH_MSG_INFO("FPGATrackSimHough1DShiftTool::readShifts found subregion " << m_subRegion);
        // Shifts
        std::vector<int> shifts;
        shifts.push_back(0); // layer 0 is implicit 0 TODO
        for (unsigned layer = 1; layer < m_nLayers; layer++)
        {
        int shift = 0;
        ok = ok && (sline >> shift);
        if (!ok) break;
        shifts.push_back(shift);
        }
        if (!ok) break;
        if (shifts[0]<-1000) {
        ATH_MSG_INFO("FPGATrackSimHough1DShiftTool::readShifts skipping line with shift out of range: " << line);
        continue;
        }
 
        // Dropable
        std::string droplist;
        ok = ok && (sline >> droplist);
        ok = ok && (droplist.size() == m_nLayers);
        if (!ok) break;
 
        boost::dynamic_bitset<> drops(m_nLayers);
        for (unsigned i = 0; i < m_nLayers; i++)
          if (droplist[i] == '1')
                drops[m_nLayers - i - 1] = true; // Droplist is printed with MSB on left
 
        // qpT
        float qpt = 0;
        ok = ok && (sline >> qpt);
        if (!ok) break;
        if ((qpt<m_qptMin) or (qpt>m_qptMax)) continue;
 
        // Phi Vals
        std::vector<float> phivals;
        for (unsigned layer = 0; layer < m_nLayers; layer++)
        {
        float phival = 0;
        ok = ok && (sline >> phival);
        if (!ok) break;
        phivals.push_back(phival);
        }
 
        m_qpt.push_back(qpt);
        m_shifts.push_back(std::move(shifts));
        m_dropable.push_back(std::move(drops));
        m_phivals.push_back(std::move(phivals));
 
 
    }
    }
 
    if (!ok)
    {
        ATH_MSG_FATAL("Found error reading file at line: " << line);
        throw "FPGATrackSimHough1DShiftTool::readShifts read error";
    }
 
    if (m_shifts.size()==0) ATH_MSG_FATAL("FPGATrackSimHough1DShiftTool::readShifts no shifts read");
    ATH_MSG_INFO("Read " << m_shifts.size() << " patterns from " << filepath);
}
 
 
StatusCode FPGATrackSimHough1DShiftTool::finalize()
{
    return StatusCode::SUCCESS;
}
 

// Main Algorithm
 
StatusCode FPGATrackSimHough1DShiftTool::getRoads(const std::vector<std::shared_ptr<const FPGATrackSimHit>> & hits, std::vector<std::shared_ptr<const FPGATrackSimRoad>> & roads)
{
    
    roads.clear();
    m_roads.clear();
 
    ATH_MSG_DEBUG("Input Hits Size:" << hits.size() << "\n");
 
    // Get hit masks
    std::vector<boost::dynamic_bitset<>> hitMasks(makeHitMasks(hits));
    if (m_drawHitMasks) drawHitMasks(hitMasks, m_name + "_e" + std::to_string(m_event));
 
    // Iterate over shifts
    for (size_t iShift = 0; iShift < m_shifts.size(); iShift++)
    {
          // Track hit layers in each bin
        std::vector<boost::dynamic_bitset<>> binHits(m_phiBins, boost::dynamic_bitset<>(m_nLayers));
 
 
        // Add the counts
        for (unsigned i = 0; i < m_nLayers; i++)
            updateBinHits(binHits, i, lshift(hitMasks[i], m_shifts[iShift][i]));
 
        // Check the threshold
        for (unsigned bin = 0; bin < m_phiBins; bin++)
        {
        // First check we're not missing hits in not allowed layers
        if (m_applyDropable && !m_dropable.empty() && (~(binHits[bin] | m_dropable[iShift])).any()) continue;
 
        m_currentcounts[bin]=binHits[bin].count();
 
            if (passThreshold(binHits,bin))
            {
          FPGATrackSimRoad r = makeRoad(hits, bin, iShift);
 
          if (m_phiRangeCut && (r.getX() > m_regionMax.phi || r.getX() < m_regionMin.phi)) continue;
 
          m_roads.push_back(r);
 
          ATH_MSG_DEBUG("New Road: "<< layersHit(r) <<" lyrs,  " << r.getNHits() << " hits :"
               << to_string(r.getNHits_layer()) << " reg=" <<  r.getSubRegion()
               << " bin=" << bin << " shift=" << iShift << " phi=" << r.getX() << " pti=" << r.getY() << " " << m_qpt[iShift]);
 
 
            }
 
        }
 
    // Add/Remove history
    m_vetolist.push_front(m_currentcounts);
    if (m_vetolist.size() > m_historyWindow) {
        m_vetolist.pop_back();
    }
    }
 
    roads.reserve(m_roads.size());
    for (FPGATrackSimRoad & r : m_roads) roads.emplace_back(std::make_shared<const FPGATrackSimRoad>(r));
 
    if (roads.size()==0 && m_drawHitMasks) drawHitMasks(hitMasks, m_name + "_fail_e" + std::to_string(m_event));
 
    m_event++;
    return StatusCode::SUCCESS;
}
 
 
 
bool FPGATrackSimHough1DShiftTool::passThreshold(std::vector<boost::dynamic_bitset<>>& binHits, int bin ) const
{
    // Check the threshold
    if (binHits[bin].count() <  m_threshold) return false;
 
    // Apply neighbor veto
    if (m_neighborWindow>0) {
    for (int i = -m_neighborWindow; i <= m_neighborWindow; i++) {
        if ((bin+i < 0) or ((bin+i)>=int(m_phiBins))) continue; // ignore edges
        if (binHits[bin+i].count()>binHits[bin].count()) {
        // neighbor has more layers
        return false;
        }
        if (i!=0 && (binHits[bin+i].count()==binHits[bin].count())) {
        // favor lower phi bin
        return false;
        }
        for (unsigned j = 0; j < m_vetolist.size(); j++) {
        if (m_vetolist[j][bin+i]>binHits[bin].count()) {
            // past neighbor has more layers
            return false;
        }
        if ((m_vetolist[j][bin+i]==binHits[bin].count()) and (i<0)) {
            // favor previous shift and lower phi bin
            return false;
        }
        }
    }
    }
 
    return true; // passed threshold, wasn't vetoed by neighbors
 
}
 
 
 
std::vector<boost::dynamic_bitset<>> FPGATrackSimHough1DShiftTool::makeHitMasks(const std::vector<std::shared_ptr<const FPGATrackSimHit>> & hits)
{
    std::vector<boost::dynamic_bitset<>> hitMasks(m_nLayers, boost::dynamic_bitset<>(m_phiBins));
    for (auto const &hit : hits)
    {
        if (m_subRegion >= 0 && !m_FPGATrackSimMapping->SubRegionMap()->isInRegion(m_subRegion, *hit)) continue;
 
        auto bins = getBins(hit);
 
        for (int i = std::max(bins.first, 0); i <= std::min(bins.second, (int)m_phiBins - 1); i++)
            hitMasks[hit->getLayer()][i] = true;
    }
 
    return hitMasks;
}
 
 
FPGATrackSimRoad FPGATrackSimHough1DShiftTool::makeRoad(const std::vector<std::shared_ptr<const FPGATrackSimHit>>& hits, int bin_track, size_t iShift)
{
    std::vector<int> const & shifts = m_shifts[iShift];
    float qpT = m_qpt[iShift];
 
    std::vector<std::shared_ptr<const FPGATrackSimHit>> road_hits;
    layer_bitmask_t hitLayers = 0;
 
    for (const auto & hit : hits)
    {
        if (m_subRegion >= 0 && !m_FPGATrackSimMapping->SubRegionMap()->isInRegion(m_subRegion, *hit)) continue;
 
        // Get the shifted bins of the hit
        auto bins = getBins(hit);
        bins.first += shifts[hit->getLayer()]; // note boost::dynamic_bitset stores [0] as the LSB, i.e. rightmost. So leftshift = +bin
        bins.second += shifts[hit->getLayer()];
 
        // Check if it's the same bin as the track
        if (bin_track >= bins.first && bin_track <= bins.second)
        {
            road_hits.push_back(hit);
            hitLayers |= 1 << hit->getLayer();
     }
    }
 
    auto sorted_hits = ::sortByLayer(road_hits);
    sorted_hits.resize(m_nLayers); // If no hits in last layer, return from sortByLayer will be too short
    // Combination of last two addRoad() functions from FPGATrackSimHoughTransformTool.cxx are implemented above (up to here)
    // Below want to look at first addRoad()/matchIdealGeoSector() function in FPGATrackSimHoughTransformTool.cxx
 
    FPGATrackSimRoad r;
    r.setHitLayers(hitLayers);
    r.setHits(std::vector<std::vector<std::shared_ptr<const FPGATrackSimHit>>>(std::move(sorted_hits)));
    r.setSubRegion(m_subRegion);
    if (m_fieldCorrection) {
      int inner_bin = static_cast<int>(bin_track)-static_cast<int>(shifts[0]);
      if ((inner_bin < 0) || (inner_bin >= static_cast<int>(m_phiBins))) {
    r.setX(-100000);
      } else {
    r.setX(m_bins[inner_bin] + 0.5*m_phiStep + deltaPhi(m_r[0],qpT));
      }
    } else {
      r.setX(phitrk(bin_track,shifts).first); // will be a large negative number if invalid
    }
    r.setY(qpT);
 
    return r;
    // TODO sector, wildcard layers?
}
 

// Helpers
 
// Given a relative shift between iterLayer and layer 0, returns the corresponding qpt.
// This does a linear approximation of the Hough transform equation.
float FPGATrackSimHough1DShiftTool::getPtFromShiftDiff(int shift) const
{
    if (m_iterLayer == 0u) ATH_MSG_FATAL("getPtFromShiftDiff() iterLayer can't be 0");
    return (shift * m_phiStep / fpgatracksim::A) / (m_r[m_iterLayer] - m_r[0]);
}
 
 
// Returns the range of bins (inclusive) given a phi and an extension in number of bins
std::pair<int, int> FPGATrackSimHough1DShiftTool::getBins(const std::shared_ptr<const FPGATrackSimHit>& hit) const
{
    float phi = hit->getGPhi();
    float bin_extend = m_hitExtend[hit->getLayer()];
    float center = (phi - m_phiMin) / m_phiStep;
 
    if (m_variableExtend){
      float r = hit->getR();
      float dphimax = deltaPhi(r,m_qptMax);
      float maxshift = +1*((std::sin(dphimax)*(r-m_r[hit->getLayer()]))/r)/m_phiStep;
      float dphimin = deltaPhi(r,m_qptMin);
      float minshift = +1*((std::sin(dphimin)*(r-m_r[hit->getLayer()]))/r)/m_phiStep;
 
      center += (maxshift+minshift)/2.0;
      bin_extend += std::abs((maxshift-minshift)/2.0);
 
    }
 
    int low = std::max(static_cast<int>(center - bin_extend),0);
    int high = std::min(static_cast<int>(center + bin_extend),static_cast<int>(m_phiBins-1));
    return { low, high };
}
 
float FPGATrackSimHough1DShiftTool::qPt(float r, float deltaPhi) const
{
    if (m_useDiff) {
      float r1=m_r[0];
      float r2=r;
      float sign = deltaPhi>0 ? 1 : -1;
      return sign*1/(2*fpgatracksim::A) * std::sqrt((4*std::sin(deltaPhi)*std::sin(deltaPhi))/( r1*r1 + r2*r2 -2*r2*r1*std::cos(deltaPhi)));
    }
    return std::sin(deltaPhi) / (fpgatracksim::A * r);
}
 
float FPGATrackSimHough1DShiftTool::phitrkDiff(float r1, float phi1,  float r2,  float phi2) const
{
   float phi_track = phi1+ std::atan2(r2-r1*std::cos(phi2-phi1),r1*std::sin(phi2-phi1)) - TMath::Pi()/2.0;
  return phi_track;
}
 
 
std::pair<float, bool> FPGATrackSimHough1DShiftTool::phitrk(int bin, std::vector<int> const &  shifts ) const
{
  int inner_bin = static_cast<int>(bin)-static_cast<int>(shifts[0]);
  int outer_bin = static_cast<int>(bin)-static_cast<int>(shifts[m_nLayers-1]);
  if ((inner_bin < 0) || (inner_bin >= static_cast<int>(m_phiBins))) return {-100000,false};
  if ((outer_bin < 0) || (outer_bin >= static_cast<int>(m_phiBins))) return {-100000,false};
  float phi1 = m_bins[inner_bin];
  float phi2 = m_bins[outer_bin];
  float phi_track = phitrkDiff(m_r[0],phi1,m_r[m_nLayers-1],phi2)+0.5*m_phiStep;
  return {phi_track,true};
}
 
 
float FPGATrackSimHough1DShiftTool::deltaPhi(float r, float qPt) const
{
   float dPhi = std::asin(fpgatracksim::A * r * qPt);
    if (m_fieldCorrection) dPhi += fieldCorrection(m_EvtSel->getRegionID(), qPt, r);
    return dPhi;
}
 
 
static inline std::string to_string(std::vector<size_t> v)
{
    std::ostringstream oss;
    oss << "[";
    if (!v.empty())
    {
        std::copy(v.begin(), v.end()-1, std::ostream_iterator<size_t>(oss, ", "));
        oss << v.back();
    }
    oss << "]";
    return oss.str();
}
 
 
static inline boost::dynamic_bitset<> lshift(boost::dynamic_bitset<> const & b, int n)
{
    if (n < 0) return rshift(b, -n);
    return b << n;
}
 
static inline boost::dynamic_bitset<> rshift(boost::dynamic_bitset<> const & b, int n)
{
    if (n < 0) return lshift(b, -n);
 
    boost::dynamic_bitset<> out(b >> n);
 
    // Force 0-padding
    for (int i = 0; i < n; i++)
        out[out.size() - 1 - i] = false;
 
    return out;
}
 
static inline void updateBinHits(std::vector<boost::dynamic_bitset<>> & binHits, unsigned layer, boost::dynamic_bitset<> const & b)
{
    for (size_t i = 0; i < b.size(); i++)
        if (b[i]) binHits[i].set(layer);
}
 
void FPGATrackSimHough1DShiftTool::printHitMasks(std::vector<boost::dynamic_bitset<>> const & hitMasks) const
{
    std::stringstream ss;
    ss << "Hit Masks:\n";
    for (auto const & b : hitMasks)
    {
        ss << "\t";
        for (size_t i = 0; i < b.size(); i++)
        {
            if (b[i]) ss << 1;
            else ss << ".";
        }
        ss << "\n";
    }
    ATH_MSG_DEBUG(ss.str() << "\n\n");
}
 
void FPGATrackSimHough1DShiftTool::drawHitMasks(std::vector<boost::dynamic_bitset<>> const & hitMasks, std::string const & name)
{
    m_monitorFile.cd();
 
    TH2F h(name.c_str(), "Hough 1D Shift;phi;layer",
            m_phiBins, m_phiMin, m_phiMax,
            m_nLayers, 0, m_nLayers
    );
 
    for (size_t layer = 0; layer < m_nLayers; layer++)
        for (size_t i = 0; i < m_phiBins; i++)
            h.SetBinContent(i+1, layer+1, hitMasks[layer][i]); // +1 since root bins are 1-indexed
 
    h.Write();
}
 
void FPGATrackSimHough1DShiftTool::drawHitMasks(std::vector<boost::dynamic_bitset<>> const & hitMasks, std::string const & name, std::vector<int> const & shifts)
{
    std::vector<boost::dynamic_bitset<>> shiftedMasks;
    for (size_t layer = 0; layer < m_nLayers; layer++)
        shiftedMasks.push_back(lshift(hitMasks[layer], shifts[layer]));
 
    drawHitMasks(shiftedMasks, name);
}
 
void FPGATrackSimHough1DShiftTool::printShifts() const
{
    std::stringstream ss;
    ss << "Shifts:\n";
    for (size_t i = 0; i < m_shifts.size(); i++)
    {
        float qpt = qPt(m_r[m_iterLayer], m_phiStep * m_shifts[i][m_iterLayer]); // q/pT represented by this shift
        ss << "q/pT=" << qpt << "; ";
        for (int shift : m_shifts[i]) ss << shift << " ";
        if (!m_dropable.empty()) ss << m_dropable[i];
        ss << "\n";
    }
    ATH_MSG_VERBOSE(ss.str());
}
 
 
void FPGATrackSimHough1DShiftTool::calculated0Shifts()
{
    int steps=1;
    while (true) {
      float d0step = steps*m_phiStep*m_r[0];
      ATH_MSG_DEBUG("d0step = " << d0step);
      std::vector<int> d0shift;
      for (unsigned lyr = 0; lyr < m_nLayers; lyr++) {
         float phi_for_d0step = d0step/m_r[lyr];
         int shift = static_cast<int>(round(phi_for_d0step/ m_phiStep));
         d0shift.push_back(shift);
      }
      m_d0shifts.push_back(std::move(d0shift));
      if (d0step>m_d0spread) break;
      ++steps;
    }
    ATH_MSG_DEBUG("d0 Shifts Found = " << m_d0shifts.size());
}
 
std::vector<int> FPGATrackSimHough1DShiftTool::applyVariation(const std::vector<int>& base, const std::vector<int>& var, int sign) const
{
    std::vector<int> retv;
 
    if (base.size()!=var.size()) {
      ATH_MSG_ERROR("Base and Var lengths must match " << base.size() << " " << var.size() );
    }
 
    for (unsigned i = 0; i < base.size(); i++) {
      retv.push_back(base[i]+sign*var[i]);
    }
    return retv;
}
 
std::vector<int> FPGATrackSimHough1DShiftTool::shiftWithDrop(std::vector<int>& shift,unsigned droplayer) const
{
  std::vector<int> retv(m_nLayers-1);
  for (unsigned lyr = 0; lyr < m_nLayers; lyr++) {
    if (lyr !=droplayer) retv.push_back(shift[lyr]);
  }
  return retv;
}
 
void FPGATrackSimHough1DShiftTool::calculateDropable()
{
 
  // one set per layer with shift set
  std::vector< std::set< std::vector<int> > > reducedShifts(m_nLayers);
 
  m_dropable.resize(m_shifts.size());
 
  for (size_t iShift = 0; iShift < m_shifts.size(); iShift++)
  {
    boost::dynamic_bitset<> drops(m_nLayers);
    for (unsigned droplayer =0; droplayer < m_nLayers; droplayer++) {
       if (reducedShifts[droplayer].insert(shiftWithDrop(m_shifts[iShift],droplayer)).second) {
          // true if the is a new shift in the set
          drops.set(droplayer);
       }
    }
    
    m_dropable[iShift]=std::move(drops);
 
  }
 
}
 
 
static inline int layersHit(FPGATrackSimRoad& r) {
  int cnt =0;
  for (unsigned i = 0; i < r.getNLayers(); i++) {
    if (r.getHitLayers()  &  (1<<i)) cnt++;
  }
  return cnt;
}