L1GTTInputProducer.cc

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// -*- C++ -*-
//
// Package:    L1Trigger/L1TTrackMatch
// Class:      L1GTTInputProducer
//
//
// Original Author:  Alexx Perloff
//         Created:  Sat, 20 Feb 2021 17:02:00 GMT
//
//

// user include files
#include "DataFormats/Common/interface/Handle.h"
#include "DataFormats/Common/interface/View.h"
#include "DataFormats/L1TrackTrigger/interface/TTTypes.h"
#include "FWCore/Framework/interface/Frameworkfwd.h"
#include "FWCore/Framework/interface/global/EDProducer.h"
#include "FWCore/Framework/interface/Event.h"
#include "FWCore/Framework/interface/MakerMacros.h"
#include "FWCore/MessageLogger/interface/MessageLogger.h"
#include "FWCore/ParameterSet/interface/ConfigurationDescriptions.h"
#include "FWCore/ParameterSet/interface/ParameterSet.h"
#include "FWCore/ParameterSet/interface/ParameterSetDescription.h"
#include "FWCore/Utilities/interface/EDMException.h"
#include "FWCore/Utilities/interface/StreamID.h"

// Vivado HLS includes
#include <ap_fixed.h>
#include <ap_int.h>

// system include files
#define _USE_MATH_DEFINES
#include <cmath>
#include <string>
#include <sstream>
#include <vector>

//
// class declaration
//

class L1GTTInputProducer : public edm::global::EDProducer<> {
public:
  explicit L1GTTInputProducer(const edm::ParameterSet&);
  ~L1GTTInputProducer() override;

  static void fillDescriptions(edm::ConfigurationDescriptions& descriptions);

private:
  // ----------constants, enums and typedefs ---------
  static constexpr unsigned int Npars4 = 4;
  static constexpr unsigned int Npars5 = 5;
  enum ConversionBitWidths {
    kEtaMagSize = 3,     // eta output magnitude size; MAG + FRAC should be <= kEtaInputSize
    kEtaFracSize = 5,    // eta output fraction size; MAG + FRAC should be <= kEtaInputSize
    kEtaInputSize = 16,  // size of tan(lambda)

    kPTMagSize = 7,     // magnitude output size; MAG + FRAC should be <= kPTInputSize
    kPTFracSize = 3,    // fraction output size; MAG + FRAC should be <= kPTInputSize
    kPTInputSize = 15,  // size of 1/R

    kEtaOutputSize = kEtaMagSize + kEtaFracSize,  // total bit width for eta
    kPTOutputSize = kPTMagSize + kPTFracSize,     // total bit width for pT
  };

  static constexpr double kEtaErrThresh = 0.0485;  // error corresponding to 0.25 of a degree error in lambda

  static constexpr double kPTErrThresh = 5;                    // error threshold in percent
  static constexpr double kSynchrotron = (1.0 / (0.3 * 3.8));  // 1/(0.3*B) for 1/R to 1/pT conversion
  static constexpr unsigned int kPtLutSize = (1 << ConversionBitWidths::kPTOutputSize);
  static constexpr unsigned int kEtaLutSize = (1 << (ConversionBitWidths::kEtaOutputSize - 1));

  typedef TTTrack<Ref_Phase2TrackerDigi_> L1Track;
  typedef std::vector<L1Track> TTTrackCollection;
  typedef edm::View<L1Track> TTTrackCollectionView;
  typedef ap_fixed<kEtaOutputSize, kEtaMagSize, AP_RND_CONV, AP_SAT> out_eta_t;
  typedef TTTrack_TrackWord::tanl_t in_eta_t;
  typedef ap_ufixed<kPTOutputSize, kPTMagSize, AP_RND_CONV, AP_SAT> out_pt_t;
  typedef TTTrack_TrackWord::rinv_t in_pt_t;
  typedef ap_uint<1> out_charge_t;

  // ----------member functions ----------------------
  void generate_eta_lut();
  void generate_pt_lut();
  bool getEtaBits(
      const L1Track& track, out_eta_t& etaBits, double& expected, double& maxErrPerc, double& maxErrEpsilon) const;
  bool getPtBits(const L1Track& track,
                 out_pt_t& ptBits,
                 out_charge_t& chargeBit,
                 double& expected,
                 double& maxErrPerc,
                 double& maxErrEpsilon,
                 double& minErrPerc,
                 double& minExpected) const;
  double indexTanLambda2Eta(unsigned int indexTanLambda) const;
  double inverseRT2InversePT(unsigned int indexRT) const;
  void produce(edm::StreamID, edm::Event&, const edm::EventSetup&) const override;
  template <typename T>
  int sgn(T val) const {
    return (T(0) < val) - (val < T(0));
  }  // From https://stackoverflow.com/questions/1903954/is-there-a-standard-sign-function-signum-sgn-in-c-c
  double unpackSignedValue(unsigned int bits, unsigned int nBits, double lsb) const;

  // ----------member data ---------------------------
  const edm::EDGetTokenT<TTTrackCollectionView> l1TracksToken_;
  const std::string outputCollectionName_;
  int debug_;
  std::vector<out_pt_t> pt_lut_;
  std::vector<out_eta_t> eta_lut_;
};

//
// constructors and destructor
//
L1GTTInputProducer::L1GTTInputProducer(const edm::ParameterSet& iConfig)
    : l1TracksToken_(consumes<TTTrackCollectionView>(iConfig.getParameter<edm::InputTag>("l1TracksInputTag"))),
      outputCollectionName_(iConfig.getParameter<std::string>("outputCollectionName")),
      debug_(iConfig.getParameter<int>("debug")) {
  // Generate the required luts
  generate_eta_lut();
  generate_pt_lut();

  // Define EDM output to be written to file (if required)
  produces<TTTrackCollection>(outputCollectionName_);
  produces<std::vector<double>>("L1GTTInputTrackPtExpected");
  produces<std::vector<double>>("L1GTTInputTrackEtaExpected");
}

L1GTTInputProducer::~L1GTTInputProducer() {}

//
// member functions
//

void L1GTTInputProducer::generate_eta_lut() {
  // initialize lut array
  eta_lut_.reserve(kEtaLutSize);

  // iterate through all values in the lut
  for (unsigned int i = 0; i < kEtaLutSize; i++) {
    // -1 to ignore sign bit for input
    unsigned int index = ((i + 0.5) * pow(2, (int)(kEtaInputSize - kEtaOutputSize)));
    double newValue = indexTanLambda2Eta(index);  // map out the index to the represented eta
    out_eta_t out_eta = newValue;                 // cast it to fxp
    eta_lut_[i] = out_eta;                        // add value for the lut
  }

  if (debug_ >= 3) {
    edm::LogInfo log("L1GTTInputProducer");
    log << "generate_eta_lut::The eta_lut_[" << kEtaLutSize << "] values are ... \n";
    for (unsigned int i = 0; i < kEtaLutSize; i++) {
      log << "\t" << i << "\t" << eta_lut_[i] << "\n";
    }
  }
}

void L1GTTInputProducer::generate_pt_lut() {
  // initialize lut array
  pt_lut_.reserve(kPtLutSize);  // generate lut

  // iterate through all values in the lut
  for (unsigned int i = 0; i < kPtLutSize; i++) {
    unsigned int index = (i + 0.5) * pow(2, (int)(kPTInputSize - 1 - kPTOutputSize));
    double newValue = inverseRT2InversePT(index);  //map out the index to the represented 1/pT
    out_pt_t out_pt = 1.0 / newValue;              // take the reciprocal and cast as an AP fixed-point (1/pt ==> pt)
    pt_lut_[i] = out_pt;                           // setting the i-th value for the lut
  }

  if (debug_ >= 3) {
    edm::LogInfo log("L1GTTInputProducer");
    log << "generate_pt_lut::The pt_lut_[" << kPtLutSize << "] values are ... \n";
    for (unsigned int i = 0; i < kPtLutSize; i++) {
      log << "\t" << i << "\t" << pt_lut_[i] << "\n";
    }
  }
}

double L1GTTInputProducer::unpackSignedValue(unsigned int bits, unsigned int nBits, double lsb) const {
  // Check that none of the bits above the nBits-1 bit, in a range of [0, nBits-1], are set.
  // This makes sure that it isn't possible for the value represented by 'bits' to be
  //  any bigger than ((1 << nBits) - 1).
  assert((bits >> nBits) == 0);

  // Convert from twos compliment to C++ signed integer (normal digitized value)
  int digitizedValue = bits;
  if (bits & (1 << (nBits - 1))) {  // check if the 'bits' is negative
    digitizedValue -= (1 << nBits);
  }

  // Convert to floating point value
  return (double(digitizedValue) + 0.5) * lsb;
}

double L1GTTInputProducer::indexTanLambda2Eta(unsigned int indexTanLambda) const {
  double tanl = unpackSignedValue(indexTanLambda, kEtaInputSize, TTTrack_TrackWord::stepTanL);
  double theta = (M_PI / 2.0) - atan(tanl);
  double eta = -1.0 * log(tan(theta / 2.0));
  if (debug_ >= 3) {
    edm::LogInfo("L1GTTInputProducer") << "indexTanLambda2Eta::tanl index = " << indexTanLambda << "\n"
                                       << "indexTanLambda2Eta::tanl value = " << tanl << "\n"
                                       << "indexTanLambda2Eta::theta = " << theta << "\n"
                                       << "indexTanLambda2Eta::eta = " << eta;
  }
  return eta;
}

double L1GTTInputProducer::inverseRT2InversePT(unsigned int indexRT) const {
  double inverseRT = unpackSignedValue(indexRT, kPTInputSize, TTTrack_TrackWord::stepRinv);
  return 100.0 * kSynchrotron * inverseRT;  // multiply by 100 to convert from cm to m
}

bool L1GTTInputProducer::getEtaBits(
    const L1Track& track, out_eta_t& etaBits, double& expected, double& maxErrPerc, double& maxErrEpsilon) const {
  // Conver the input to an ap_uint
  in_eta_t value = track.getTanlWord();

  // Get the expected outcome (floating point)
  out_eta_t maxValuePossible = pow(2, 15);  // saturate at max value possible for fxp
  expected = indexTanLambda2Eta(value);     // expected value for eta
  if (expected > maxValuePossible) {
    expected = maxValuePossible;
  }

  // Converted value (emulation)
  // Masking and shifting converts the efficient bit representation into an index
  // Start by setting up the masks
  in_eta_t indexTanLambda = value;
  in_eta_t mask = ~0;                                                      // mask (all 1's)
  bool sign = indexTanLambda.range(kEtaInputSize - 1, kEtaInputSize - 1);  // sign bit of indexTanLambda
  mask *= sign;  // all 0's for positive numbers, all 1's for negative numbers

  // Take the absolute value of indexTanLambda (2's complement)
  indexTanLambda ^= mask;
  indexTanLambda += sign;

  // Find the value for eta, not |eta|
  indexTanLambda =
      indexTanLambda >>
      (kEtaInputSize -
       kEtaOutputSize);  // Don't subtract 1 because we now want to take into account the sign bit of the output
  indexTanLambda =
      (indexTanLambda < (1 << (kEtaOutputSize - 1))) ? indexTanLambda : in_eta_t((1 << (kEtaOutputSize - 1)) - 1);
  etaBits = eta_lut_[indexTanLambda];

  // Reinacting the sign
  out_eta_t maskOut;
  maskOut.V = ~0;
  maskOut *= sign;
  etaBits ^= maskOut;
  etaBits.V += sign;

  // Compare the floating point calculation to the emulation
  double delta = std::abs(expected - etaBits.to_double());
  double perc_diff = (delta / std::abs(expected)) * 100.;  // calc percentage error
  if (delta > maxErrEpsilon) {
    maxErrPerc = perc_diff;
    maxErrEpsilon = delta;
  }

  if (delta >= kEtaErrThresh) {
    edm::LogError("L1GTTInputProducer") << "getEtaBits::MISMATCH!!!\n"
                                        << "\tTTTrack tanL = " << track.tanL() << "\n"
                                        << "\tTTTrack eta = " << track.momentum().eta() << "\n"
                                        << "\tTTTrack_TrackWord = " << track.getTrackWord().to_string(2) << "\n"
                                        << "\tTTTrack_TrackWord tanlWord = " << track.getTanlWord() << " ("
                                        << track.getTanlWord().to_string(2) << ")\n"
                                        << "\tin_eta_t value = " << value << " (" << value.to_string(2) << ")\n"
                                        << "\tExpected value = " << expected << "\n"
                                        << "\tCalculated eta = " << etaBits.to_double() << " (" << etaBits.to_string(2)
                                        << ") @ index " << indexTanLambda << "\n"
                                        << "\tDelta = " << delta << "\tpercentage error = " << perc_diff;
    return true;
  } else {
    if (debug_ >= 2) {
      edm::LogInfo("L1GTTInputProducer")
          << "getEtaBits::SUCCESS (TTTrack, floating eta calculation, bitwise calculation, initial index, lut index) = "
          << "(" << track.momentum().eta() << ", " << expected << ", " << etaBits << ", " << value << ", "
          << indexTanLambda << ")";
    }
  }

  return false;
}

bool L1GTTInputProducer::getPtBits(const L1Track& track,
                                   out_pt_t& ptBits,
                                   out_charge_t& chargeBit,
                                   double& expected,
                                   double& maxErrPerc,
                                   double& maxErrEpsilon,
                                   double& minErrPerc,
                                   double& minExpected) const {
  // Convert the input to an ap_uint
  in_pt_t value = track.getRinvWord();
  in_pt_t value_initial = value;

  // Get the expected outcome (floating point)
  out_pt_t maxValuePossible = pow(2, 16);       // saturate at max value possible for fxp
  expected = 1.0 / inverseRT2InversePT(value);  // expected value for inverse
  bool saturation = true;
  if (std::abs(expected) > maxValuePossible) {
    expected = maxValuePossible;
  } else {
    saturation = false;
  }

  // Converted value (emulation)
  // Masking and shifting converts the efficient bit representation into an index
  // Start by setting up the masks
  in_pt_t mask = ~0;                                            // mask (all 1's)
  bool sign = value.range(kPTInputSize - 1, kPTInputSize - 1);  // sign bit of value
  mask *= sign;  // all 0's for positive numbers, all 1's for negative numbers

  // Take the absolute value of value (2's complement)
  value ^= mask;
  value += sign;

  // Shift the value so that the index changes when the LSB of the output changes
  value = value >> (kPTInputSize - 1 - (kPTOutputSize));

  // Get the pt from the LUT
  ptBits = pt_lut_[value];

  // Set the charge bit
  chargeBit = sign;
  double charge = 1. - (2 * chargeBit.to_uint());

  // Compare the floating point calculation to the emulation
  double delta = std::abs(expected - (charge * ptBits.to_double()));
  double perc_diff = (delta / std::abs(expected)) * 100.;

  if (delta > maxErrEpsilon) {
    maxErrPerc = perc_diff;
    maxErrEpsilon = delta;
  } else if (delta < minExpected && !saturation && minErrPerc > 100.0) {
    minErrPerc = perc_diff;
    minExpected = expected;
  }

  if (std::abs(perc_diff) >= kPTErrThresh && !saturation) {
    edm::LogError("L1GTTInputProducer") << "getPtBits::MISMATCH!!!\n"
                                        << "\tTTTrack Rinv = " << track.rInv() << "\n"
                                        << "\tTTTrack pt = " << track.momentum().transverse() << "\n"
                                        << "\tTTTrack_TrackWord = " << track.getTrackWord().to_string(2) << "\n"
                                        << "\tTTTrack_TrackWord RinvWord = " << track.getRinvWord() << " ("
                                        << track.getRinvWord().to_string(2) << ")\n"
                                        << "\tin_pt_t value = " << value_initial << " (" << value_initial.to_string(2)
                                        << ")\n"
                                        << "\tExpected value = " << expected << "\n"
                                        << "\tCalculated pt = " << ptBits.to_double() << " (" << ptBits.to_string(2)
                                        << ") @ index " << value << "\n"
                                        << "\tcharge = " << charge << " (bit = " << chargeBit << ")\n"
                                        << "\tDelta = " << delta << "\tpercentage error = " << perc_diff;
    return true;
  } else {
    if (debug_ >= 2) {
      edm::LogInfo("L1GTTInputProducer") << "getPtBits::SUCCESS (TTTrack, floating pt calculation, charge, bitwise "
                                            "calculation, initial index, lut index) = "
                                         << "(" << sgn(track.rInv()) * track.momentum().transverse() << ", " << expected
                                         << ", " << charge << ", " << ptBits << ", " << value_initial << ", " << value
                                         << ")";
    }
  }

  return false;
}

// ------------ method called to produce the data  ------------
void L1GTTInputProducer::produce(edm::StreamID, edm::Event& iEvent, const edm::EventSetup& iSetup) const {
  auto vTTTrackOutput = std::make_unique<TTTrackCollection>();
  auto vPtOutput = std::make_unique<std::vector<double>>();
  auto vEtaOutput = std::make_unique<std::vector<double>>();

  edm::Handle<TTTrackCollectionView> l1TracksHandle;
  iEvent.getByToken(l1TracksToken_, l1TracksHandle);

  out_charge_t chargeBit = 0;
  out_pt_t ptBits = 0;
  out_eta_t etaBits = 0;
  in_pt_t ptBitsShifted = 0;
  in_eta_t etaBitsShifted = 0;
  unsigned int error_pt_c = 0;        // error counter
  unsigned int error_eta_c = 0;       // error counter
  double expectedPt = 0.0;            // expected value of the pt
  double expectedEta = 0.0;           // expected value of the eta
  double maxErrPercPt = 0.0;          // stores the maximum error percentage
  double maxErrPercEta = 0.0;         // stores the maximum error percentage
  double maxErrEpsilonPt = 0.0;       // keeps track of epsilon for max error
  double maxErrEpsilonEta = 0.0;      // keeps track of epsilon for max error
  double minErrPercPt = 10000000.0;   // stores the maximum error percentage
  double minExpectedPt = 10000000.0;  // keeps track of epsilon for max error

  unsigned int nOutput = l1TracksHandle->size();
  vTTTrackOutput->reserve(nOutput);
  vPtOutput->reserve(nOutput);
  vEtaOutput->reserve(nOutput);
  for (const auto& track : *l1TracksHandle) {
    if (!(track.nFitPars() == Npars4 || track.nFitPars() == Npars5)) {
      throw cms::Exception("nFitPars unknown")
          << "L1GTTInputProducer::produce method is called with numFitPars_ = " << track.nFitPars()
          << ". The only possible values are 4/5.";
    }

    // Fill the vector of tracks
    vTTTrackOutput->push_back(track);
    auto& currentTrackRef = vTTTrackOutput->back();
    if (debug_ >= 2) {
      edm::LogInfo("L1GTTInputProducer") << "produce::word before anything "
                                         << currentTrackRef.getTrackWord().to_string(2);
    }

    // Do an initial setting of the bits based on the floating point values
    currentTrackRef.setTrackWordBits();
    if (debug_ >= 2) {
      edm::LogInfo("L1GTTInputProducer") << "produce::word after initial setting of the track word "
                                         << currentTrackRef.getTrackWord().to_string(2);
    }

    // Do the conversions
    error_pt_c += getPtBits(
        currentTrackRef, ptBits, chargeBit, expectedPt, maxErrPercPt, maxErrEpsilonPt, minErrPercPt, minExpectedPt);
    error_eta_c += getEtaBits(currentTrackRef, etaBits, expectedEta, maxErrPercEta, maxErrEpsilonEta);

    // Assign the exat same bits to an ap_uint
    ptBitsShifted = ptBits.range();
    etaBitsShifted = etaBits.range();

    // Shift the bits so that the decimal is in the right spot for the GTT software
    ptBitsShifted = ptBitsShifted << 2;
    etaBitsShifted = etaBitsShifted << 8;

    // Set the MSB for the pt to the sign of the incoming word
    ptBitsShifted.set(kPTInputSize - 1, chargeBit);

    // Set the correct bits based on the converted quanteties and the existing track word components
    currentTrackRef.setTrackWord(currentTrackRef.getValidWord(),
                                 ptBitsShifted,
                                 currentTrackRef.getPhiWord(),
                                 etaBitsShifted,
                                 currentTrackRef.getZ0Word(),
                                 currentTrackRef.getD0Word(),
                                 currentTrackRef.getChi2RPhiWord(),
                                 currentTrackRef.getChi2RZWord(),
                                 currentTrackRef.getBendChi2Word(),
                                 currentTrackRef.getHitPatternWord(),
                                 currentTrackRef.getMVAQualityWord(),
                                 currentTrackRef.getMVAOtherWord());
    if (debug_ >= 2) {
      edm::LogInfo("L1GTTInputProducer") << "produce::charge after all conversions " << chargeBit << "\n"
                                         << "produce::ptBits after all conversions " << ptBits.to_string(2) << " ("
                                         << ptBitsShifted.to_string(2) << " = " << ptBitsShifted.to_uint() << ")\n"
                                         << "produce::etaBits after all conversions " << etaBits.to_string(2) << " ("
                                         << etaBitsShifted.to_string(2) << " = " << etaBitsShifted.to_uint() << ")\n"
                                         << "produce::word after all conversions "
                                         << vTTTrackOutput->back().getTrackWord().to_string(2);
    }

    // Fill the remaining outputs
    vPtOutput->push_back(expectedPt);
    vEtaOutput->push_back(expectedEta);
  }

  if (debug_ >= 1) {
    edm::LogInfo("L1GTTInputProducer") << "\nNumber of converted tracks: " << nOutput << "\n\n"
                                       << "q/r ==> pt conversion:\n"
                                       << "\tError Threshold: " << kPTErrThresh << "%\n"
                                       << "\tMax error: " << maxErrEpsilonPt
                                       << " GeV difference with percentage: " << maxErrPercPt << "% @ "
                                       << 100.0 * maxErrEpsilonPt / maxErrPercPt << " GeV"
                                       << "\n"
                                       << "\tError @ max range: " << minExpectedPt
                                       << " GeV with precentage: " << minErrPercPt << "%"
                                       << "\n"
                                       << "\tTotal number of errors: " << error_pt_c << "\n\n"
                                       << "tan(lambda) ==> eta conversion:\n"
                                       << "\tError Threshold: " << kEtaErrThresh << "\n"
                                       << "\tMax error: " << maxErrEpsilonEta << " with percentage: " << maxErrPercEta
                                       << "% @ " << 100.0 * maxErrEpsilonEta / maxErrPercEta << "\n"
                                       << "\tTotal number of errors: " << error_eta_c;
  }

  if (error_pt_c + error_eta_c) {
    edm::LogError("L1GTTInputProducer") << "produce::" << error_pt_c << "/" << error_eta_c
                                        << " pt/eta mismatches detected!!!";
  }

  // Put the outputs into the event
  iEvent.put(std::move(vTTTrackOutput), outputCollectionName_);
  iEvent.put(std::move(vPtOutput), "L1GTTInputTrackPtExpected");
  iEvent.put(std::move(vEtaOutput), "L1GTTInputTrackEtaExpected");
}

// ------------ method fills 'descriptions' with the allowed parameters for the module  ------------
void L1GTTInputProducer::fillDescriptions(edm::ConfigurationDescriptions& descriptions) {
  // L1GTTInputProducer
  edm::ParameterSetDescription desc;
  desc.add<int>("debug", 0)->setComment("Verbosity levels: 0, 1, 2, 3");
  desc.add<edm::InputTag>("l1TracksInputTag", edm::InputTag("TTTracksFromTrackletEmulation", "Level1TTTracks"));
  desc.add<std::string>("outputCollectionName", "Level1TTTracksConverted");
  descriptions.addWithDefaultLabel(desc);
}

//define this as a plug-in
DEFINE_FWK_MODULE(L1GTTInputProducer);