[PWGEM,PWGEM-36] Seperate flow resolution and QA from Pi0FlowEMC task (#14287)

Author: mhemmer-cern

PWGEM/PhotonMeson/Core/CMakeLists.txt

@@ -18,6 +18,7 @@ o2physics_add_library(PWGEMPhotonMesonCore
                         EMPhotonEventCut.cxx
                         CutsLibrary.cxx
                         HistogramsLibrary.cxx
+                        EMBitFlags.cxx
                PUBLIC_LINK_LIBRARIES O2::Framework O2Physics::AnalysisCore O2Physics::MLCore O2Physics::PWGEMDileptonCore)
 
 o2physics_target_root_dictionary(PWGEMPhotonMesonCore
@@ -29,4 +30,5 @@ o2physics_target_root_dictionary(PWGEMPhotonMesonCore
                         EMPhotonEventCut.h
                         CutsLibrary.h
                         HistogramsLibrary.h
+                        EMBitFlags.h
               LINKDEF PWGEMPhotonMesonCoreLinkDef.h)

PWGEM/PhotonMeson/Core/EMBitFlags.cxx

@@ -0,0 +1,72 @@
+// Copyright 2019-2020 CERN and copyright holders of ALICE O2.
+// See https://alice-o2.web.cern.ch/copyright for details of the copyright holders.
+// All rights not expressly granted are reserved.
+//
+// This software is distributed under the terms of the GNU General Public
+// License v3 (GPL Version 3), copied verbatim in the file "COPYING".
+//
+// In applying this license CERN does not waive the privileges and immunities
+// granted to it by virtue of its status as an Intergovernmental Organization
+// or submit itself to any jurisdiction.
+
+/// \file EMBitFlags.cxx
+/// \brief Source of bit flag class for particle selection.
+/// \author M. Hemmer, marvin.hemmer@cern.ch
+
+#include "EMBitFlags.h"
+
+#include <algorithm> // fill
+#include <cassert>   // assert
+#include <cstddef>   // size_t
+
+EMBitFlags::EMBitFlags(std::size_t nBits)
+  : mBits((nBits + 63) / 64, ~0ULL),
+    mSize(nBits)
+{
+}
+
+std::size_t EMBitFlags::size() const
+{
+  return mSize;
+}
+
+bool EMBitFlags::test(std::size_t i) const
+{
+  assert(i < mSize);
+  return mBits[word(i)] & mask(i);
+}
+
+void EMBitFlags::set(std::size_t i)
+{
+  ensureSize(i + 1);
+  mBits[word(i)] &= ~mask(i);
+}
+
+void EMBitFlags::reset(std::size_t i)
+{
+  assert(i < mSize);
+  mBits[word(i)] |= mask(i);
+}
+
+void EMBitFlags::clear()
+{
+  std::fill(mBits.begin(), mBits.end(), ~0ULL);
+}
+
+void EMBitFlags::reserve(std::size_t nBits)
+{
+  mBits.reserve((nBits + 63) / 64);
+}
+
+void EMBitFlags::resize(std::size_t nBits)
+{
+  mBits.resize((nBits + 63) / 64, ~0ULL);
+  mSize = nBits;
+}
+
+void EMBitFlags::ensureSize(std::size_t nBits)
+{
+  if (nBits > mSize) {
+    resize(nBits);
+  }
+}

PWGEM/PhotonMeson/Core/EMBitFlags.h

@@ -0,0 +1,73 @@
+// Copyright 2019-2020 CERN and copyright holders of ALICE O2.
+// See https://alice-o2.web.cern.ch/copyright for details of the copyright holders.
+// All rights not expressly granted are reserved.
+//
+// This software is distributed under the terms of the GNU General Public
+// License v3 (GPL Version 3), copied verbatim in the file "COPYING".
+//
+// In applying this license CERN does not waive the privileges and immunities
+// granted to it by virtue of its status as an Intergovernmental Organization
+// or submit itself to any jurisdiction.
+
+/// \file EMBitFlags.h
+/// \brief Header of bit flag class for particle selection.
+/// \author M. Hemmer, marvin.hemmer@cern.ch
+
+#ifndef PWGEM_PHOTONMESON_CORE_EMBITFLAGS_H_
+#define PWGEM_PHOTONMESON_CORE_EMBITFLAGS_H_
+
+#include <cstddef> // size_t
+#include <cstdint> // uint64_t
+#include <vector>  // vector
+
+/// \class EMBitFlags
+/// \brief Dynamically-sized bit container with bit-level storage.
+///
+/// Bits can be set beyond the current size, in which case the container
+/// grows automatically. Access via test() and reset() requires the index
+/// to be within the current size. Bits are all on by default and will be
+/// switched off if particle fails a cut
+class EMBitFlags
+{
+ public:
+  explicit EMBitFlags(std::size_t nBits = 0);
+
+  /// \brief get number of stored bits
+  std::size_t size() const;
+
+  /// \brief check bit i
+  /// \param i index of bit that should be checked
+  bool test(std::size_t i) const;
+
+  /// \brief set bit i
+  /// \param i index of bit which value should be set
+  void set(std::size_t i);
+
+  /// \brief reset bit i
+  /// \param i index of bit which value should be reset
+  void reset(std::size_t i);
+
+  /// \brief resetting all flags to false
+  void clear();
+
+  /// \brief reserve space in the underlying storage for nBits bits
+  /// \param nBits number of bits to reserve capacity for
+  void reserve(std::size_t nBits);
+
+  /// \brief resize the container to hold nBits bits
+  /// \param nBits new number of bits (new bits are initialized to false)
+  void resize(std::size_t nBits);
+
+ private:
+  /// \brief ensure that the container can hold at least nBits bits
+  /// \param nBits required number of bits
+  void ensureSize(std::size_t nBits);
+
+  static constexpr std::size_t word(std::size_t i) { return i >> 6; }
+  static constexpr std::uint64_t mask(std::size_t i) { return 1ULL << (i & 63); }
+
+  std::vector<std::uint64_t> mBits;
+  std::size_t mSize = 0;
+};
+
+#endif // PWGEM_PHOTONMESON_CORE_EMBITFLAGS_H_