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[EMCAL-551] Move cell format to bitfield
- Move underlying structure to bitfield and expand to 48 bit (min. size) - Increase number of time bits from 9 to 11, and use an internal time shift of 600 ns in order to cover the time range from -600 ns to 900 ns with 0.7 ns precision - Add truncations for time and energy - Make truncations and resolution constants, and calculate based on the range and the max. integer number representable with the amount of bits assigned. - Add doxygen documentation for cell class - Fixes in test: - Default cell type: High gain(0) instead of LowGain(1) - Test of times should reflect negative values as time can be shifted - In practice cells with E > 16 GeV are low gain cells, energy test should reflect this
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‎DataFormats/Detectors/EMCAL/include/DataFormatsEMCAL/Cell.h‎

Lines changed: 141 additions & 42 deletions
Original file line numberDiff line numberDiff line change
@@ -12,7 +12,6 @@
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#define ALICEO2_EMCAL_CELL_H_
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#include <bitset>
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#include "Rtypes.h"
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#include "DataFormatsEMCAL/Constants.h"
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namespace o2
@@ -22,62 +21,162 @@ namespace emcal
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/// \class Cell
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/// \brief EMCAL compressed cell information
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/// \author Anders Knospe, University of Houston
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/// \author Markus Fasel <markus.fasel@cern.ch>, Oak Ridge National Laboratory
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/// \since March 6, 2019
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/// \ingroup EMCALDataFormat
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///
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/// Structure:
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/// Bits 38-39: Cell type: 00=Low Gain, 01=High Gain, 10=LED mon, 11=TRU
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/// Bits 24-37: Energy (input/output in GeV/c^2, resolution 1/16 ADC count)
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/// Bits 15-23: Time (ns)
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/// Bits 0-14: Tower ID
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/// # Base format for EMCAL cell information in the Compressed Timeframe
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///
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/// The cell class contains the relevant information for each tower per event
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/// - Tower ID
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/// - Energy of the raw fit
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/// - Time of the raw fit
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/// - Type of the cell
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/// While cell type and tower ID have a predefined range based on the hardware
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/// design, energy and time have a finite resolution influenced by the resolution
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/// of the digitizer. This is used in order to compress the information stored
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/// in the compressed timeframe by not storing the full double values but instead
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/// assigning a certain amount of bits to each information. Therefore for certain
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/// information (energy, time) precision loss has to be taken into account.
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///
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/// # Internal structure and resolution
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///
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/// The internal structure is a bit field compressing the information to
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/// 48 bits. The definition of the bit field as well as the value range and the resolution
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/// is listed in the table below:
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///
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/// | Bits | Content | Resolution | Range |
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/// |-------|---------------|---------------|-----------------------------|
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/// | 0-14 | Tower ID | - | 0 to 17644 |
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/// | 15-26 | Time (ns) | 0.73 ns | -600 to 900 ns |
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/// | 27-40 | Energy (GeV) | 0.0153 GeV | 0 to 250 GeV |
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/// | 41-42 | Cell type | - | 0=LG, 1=HG, 2=LEMon, 4=TRU |
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///
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/// The remaining bits are 0
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class Cell
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{
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public:
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Cell() = default;
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Cell(Short_t tower, Double_t energy, Double_t time, ChannelType_t ctype = ChannelType_t::LOW_GAIN);
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Cell();
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Cell(short tower, float energy, float time, ChannelType_t ctype = ChannelType_t::LOW_GAIN);
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~Cell() = default; // override
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void setTower(Short_t tower);
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Short_t getTower() const;
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void setTimeStamp(Double_t time);
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Short_t getTimeStamp() const;
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void setEnergyBits(Short_t ebits);
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Short_t getEnergyBits() const;
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void setEnergy(Double_t energy);
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Double_t getEnergy() const;
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void setAmplitude(Double_t energy) { setEnergy(energy); }
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Double_t getAmplitude() const { return getEnergy(); }
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void setType(ChannelType_t ctype);
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ChannelType_t getType() const;
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void setLowGain();
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Bool_t getLowGain() const;
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void setHighGain();
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Bool_t getHighGain() const;
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void setLEDMon();
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Bool_t getLEDMon() const;
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void setTRU();
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Bool_t getTRU() const;
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void setLong(ULong_t l);
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ULong_t getLong() const { return mBits.to_ulong(); }
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void setTower(short tower) { getDataRepresentation()->mTowerID = tower; }
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short getTower() const { return getDataRepresentation()->mTowerID; }
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/// \brief Set the time stamp
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/// \param time Time in ns
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///
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/// The time stamp is expressed in ns and has
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/// a resolution of 1 ns. The time range which can
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/// be stored is from -1023 to 1023 ns. In case the
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/// range is exceeded the time is set to the limit
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/// of the range.
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void setTimeStamp(float time);
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/// \brief Get the time stamp
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/// \return Time in ns
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///
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/// Time has a resolution of 1 ns and can cover
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/// a range from -1023 to 1023 ns
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float getTimeStamp() const;
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/// \brief Set the energy of the cell
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/// \brief Energy of the cell in GeV
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///
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/// The energy range covered by the cell
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/// is 0 - 250 GeV, with a resolution of
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/// 0.0153 GeV. In case an energy exceeding
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/// the limits is provided the energy is
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/// set to the limits (0 in case of negative
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/// energy, 250. in case of energies > 250 GeV)
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void setEnergy(float energy);
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/// \brief Get the energy of the cell
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/// \return Energy of the cell
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///
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/// The energy is truncated to a range
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/// covering 0 to 250 GeV with a resolution
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/// of 0.0153 GeV
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float getEnergy() const;
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/// \brief Set the amplitude of the cell
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/// \param amplitude Cell amplitude
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///
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/// See setEnergy for more information
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void setAmplitude(float amplitude) { setEnergy(amplitude); }
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/// \brief Get cell amplitude
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/// \return cell Amplitude
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///
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/// Set getEnergy for more information
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float getAmplitude() const { return getEnergy(); }
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/// \brief Set the type of the cell
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/// \param ctype Type of the cell (HIGH_GAIN, LOW_GAIN, LEDMON, TRU)
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void setType(ChannelType_t ctype) { getDataRepresentation()->mCellStatus = static_cast<uint16_t>(ctype); }
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/// \brief Get the type of the cell
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/// \return Type of the cell (HIGH_GAIN, LOW_GAIN, LEDMON, TRU)
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ChannelType_t getType() const { return static_cast<ChannelType_t>(getDataRepresentation()->mCellStatus); }
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/// \brief Check whether the cell is of a given type
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/// \param ctype Type of the cell (HIGH_GAIN, LOW_GAIN, LEDMON, TRU)
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/// \return True if the type of the cell matches the requested type, false otherwise
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bool isChannelType(ChannelType_t ctype) const { return getType() == ctype; }
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/// \brief Mark cell as low gain cell
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void setLowGain() { setType(ChannelType_t::LOW_GAIN); }
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/// \brief Check whether the cell is a low gain cell
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/// \return True if the cell type is low gain, false otherwise
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Bool_t getLowGain() const { return isChannelType(ChannelType_t::LOW_GAIN); }
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/// \brief Mark cell as high gain cell
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void setHighGain() { setType(ChannelType_t::HIGH_GAIN); }
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/// \brief Check whether the cell is a high gain cell
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/// \return True if the cell type is high gain, false otherwise
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Bool_t getHighGain() const { return isChannelType(ChannelType_t::HIGH_GAIN); };
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/// \brief Mark cell as LED monitor cell
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void setLEDMon() { setType(ChannelType_t::LEDMON); }
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/// \brief Check whether the cell is a LED monitor cell
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/// \return True if the cell type is LED monitor, false otherwise
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Bool_t getLEDMon() const { return isChannelType(ChannelType_t::LEDMON); }
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/// \brief Mark cell as TRU cell
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void setTRU() { setType(ChannelType_t::TRU); }
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/// \brief Check whether the cell is a TRU cell
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/// \return True if the cell type is TRU, false otherwise
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Bool_t getTRU() const { return isChannelType(ChannelType_t::TRU); }
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void PrintStream(std::ostream& stream) const;
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private:
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std::bitset<40> mBits;
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struct __attribute__((packed)) CellData {
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uint16_t mTowerID : 15; ///< bits 0-14 Tower ID
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uint16_t mTime : 11; ///< bits 15-25: Time (signed, can become negative after calibration)
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uint16_t mEnergy : 14; ///< bits 26-39: Energy
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uint16_t mCellStatus : 2; ///< bits 40-41: Cell status
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uint16_t mZerod : 6; ///< bits 42-47: Zerod
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};
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CellData* getDataRepresentation() { return reinterpret_cast<CellData*>(mCellWords); }
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const CellData* getDataRepresentation() const { return reinterpret_cast<const CellData*>(mCellWords); }
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uint16_t mCellWords[3]; ///< data word
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ClassDefNV(Cell, 1);
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};
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std::ostream& operator<<(std::ostream& stream, const Cell& c);
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/// \brief Stream operator for EMCAL cell
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/// \param stream Stream where to print the EMCAL cell
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/// \param cell Cell to be printed
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/// \return Stream after printing
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std::ostream& operator<<(std::ostream& stream, const Cell& cell);
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} // namespace emcal
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} // namespace o2
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