SiStripCluster.h

#ifndef DATAFORMATS_SISTRIPCLUSTER_H
#define DATAFORMATS_SISTRIPCLUSTER_H

#include "DataFormats/SiStripDigi/interface/SiStripDigi.h"
#include "DataFormats/SiStripCluster/interface/SiStripApproximateCluster.h"
#include <vector>
#include <numeric>
#include <iostream>

class SiStripApproximateCluster;

class SiStripCluster {
public:
  typedef std::vector<SiStripDigi>::const_iterator SiStripDigiIter;
  typedef std::pair<SiStripDigiIter, SiStripDigiIter> SiStripDigiRange;

  static const uint16_t stripIndexMask = 0x7FFF;   // The first strip index is in the low 15 bits of firstStrip_
  static const uint16_t mergedValueMask = 0x8000;  // The merged state is given by the high bit of firstStrip_

  /** Construct from a range of digis that form a cluster and from 
   *  a DetID. The range is assumed to be non-empty.
   */

  SiStripCluster() {}

  explicit SiStripCluster(const SiStripDigiRange& range);

  SiStripCluster(uint16_t firstStrip, std::vector<uint8_t>&& data)
      : amplitudes_(std::move(data)), firstStrip_(firstStrip) {}

  template <typename Iter>
  SiStripCluster(const uint16_t& firstStrip, Iter begin, Iter end) : amplitudes_(begin, end), firstStrip_(firstStrip) {}

  template <typename Iter>
  SiStripCluster(const uint16_t& firstStrip, Iter begin, Iter end, bool merged)
      : amplitudes_(begin, end), firstStrip_(firstStrip) {
    if (merged)
      firstStrip_ |= mergedValueMask;  // if this is a candidate merged cluster
  }

  SiStripCluster(const SiStripApproximateCluster cluster, const uint16_t maxStrips);

  // extend the cluster
  template <typename Iter>
  void extend(Iter begin, Iter end) {
    amplitudes_.insert(amplitudes_.end(), begin, end);
  }

  /** The amplitudes of the strips forming the cluster.
   *  The amplitudes are on consecutive strips; if a strip is missing
   *  the amplitude is set to zero.
   *  A strip may be missing in the middle of a cluster because of a
   *  clusterizer that accepts holes.
   *  A strip may also be missing anywhere in the cluster, including the 
   *  edge, to record a dead/noisy channel.
   *
   *  You can find the special meanings of values { 0, 254, 255} in section 3.4.1 of
   *  http://www.te.rl.ac.uk/esdg/cms-fed/firmware/Documents/FE_FPGA_Technical_Description.pdf
   */
  auto size() const { return amplitudes_.size(); }
  auto const* begin() const { return amplitudes_.data(); }
  auto const* end() const { return begin() + size(); }
  auto operator[](int i) const { return *(begin() + i); }
  bool empty() const { return amplitudes_.empty(); }
  bool full() const { return false; }

  SiStripCluster const& amplitudes() const { return *this; }

  /** The number of the first strip in the cluster.
   *  The high bit of firstStrip_ indicates whether the cluster is a candidate for being merged.
   */
  uint16_t firstStrip() const { return firstStrip_ & stripIndexMask; }
  uint16_t endStrip() const { return firstStrip() + size(); }

  /** The barycenter of the cluster, not corrected for Lorentz shift;
   *  should not be used as position estimate for tracking.
   */
  float barycenter() const;

  /** total charge
   *
   */
  int charge() const;

  bool filter() const;

  bool isFromApprox() const;

  /** Test (set) the merged status of the cluster
   *
   */
  bool isMerged() const { return (firstStrip_ & mergedValueMask) != 0; }
  void setMerged(bool mergedState) { mergedState ? firstStrip_ |= mergedValueMask : firstStrip_ &= stripIndexMask; }

  float getSplitClusterError() const { return error_x; }
  void setSplitClusterError(float errx) { error_x = errx; }

private:
  std::vector<uint8_t> amplitudes_;

  uint16_t firstStrip_ = 0;

  //these are used if amplitude information is not available (using approximate cluster constructor)
  float barycenter_ = 0;
  int charge_ = 0;
  bool filter_ = false;

  // ggiurgiu@fnal.gov, 01/05/12
  // Add cluster errors to be used by rechits from split clusters.
  // A rechit from a split cluster has larger errors than rechits from normal clusters.
  // However, when presented with a cluster, the CPE does not know if the cluster comes
  // from a splitting procedure or not. That's why we have to instruct the CPE to use
  // appropriate errors for split clusters.
  // To avoid increase of data size on disk,these new data members are set as transient in:
  // DataFormats/SiStripCluster/src/classes_def.xml
  float error_x = -99999.9;

  // ggiurgiu@fnal.gov, 01/05/12
  // Initialize the split cluster errors to un-physical values.
  // The CPE will check these errors and if they are not un-physical,
  // it will recognize the clusters as split and assign these (increased)
  // errors to the corresponding rechit.
};

// Comparison operators
inline bool operator<(const SiStripCluster& one, const SiStripCluster& other) {
  return one.firstStrip() < other.firstStrip();
}

inline bool operator<(const SiStripCluster& cluster, const uint16_t& firstStrip) {
  return cluster.firstStrip() < firstStrip;
}

inline bool operator<(const uint16_t& firstStrip, const SiStripCluster& cluster) {
  return firstStrip < cluster.firstStrip();
}
#endif  // DATAFORMATS_SISTRIPCLUSTER_H