added openPMD-api support for I/O

Src/Base/AMReX_PlotFileUtil.H

@@ -16,6 +16,10 @@
 #include <string>
 #include <memory>
 
+#ifdef AMREX_USE_OPENPMD_API
+#include <AMReX_PlotFileUtilOPENPMD.H>
+#endif
+
 namespace amrex
 {
     //!  return the name of the level directory,  e.g., Level_5

Src/CMakeLists.txt

@@ -200,6 +200,10 @@ if (AMReX_HDF5)
    add_subdirectory(Extern/HDF5)
 endif ()
 
+if (AMReX_OPENPMD_API)
+   add_subdirectory(Extern/openPMD-api)
+endif()
+
 #
 # Print out summary -- do it here so we already linked all
 # libs at this point

Src/Extern/openPMD-api/AMReX_ParticlesOPENPMD.H

@@ -0,0 +1,80 @@
+#ifndef AMREX_PTL_OPENPMD_API_H
+#define AMREX_PTL_OPENPMD_API_H
+
+//#include <openPMD/openpmd.hpp>
+
+
+struct AMReX_PtlCounter
+{
+  int m_MPIRank = 0;
+  int m_MPISize = 1;
+
+  unsigned long long m_Total = 0;
+
+  std::vector<unsigned long long> m_ParticleCounterByLevel;
+
+  unsigned long GetTotalNumParticles () const { return m_Total;}
+
+  std::vector<unsigned long long> m_ParticleOffsetAtRank;
+  std::vector<unsigned long long> m_ParticleSizeAtRank;
+};
+
+
+void CountParticles()
+{
+
+  m_PtlCounter.m_MPISize = amrex::ParallelDescriptor::NProcs();
+  m_PtlCounter.m_MPIRank = amrex::ParallelDescriptor::MyProc();
+
+  m_PtlCounter.m_ParticleCounterByLevel.resize(this->finestLevel()+1);
+  m_PtlCounter.m_ParticleOffsetAtRank.resize(this->finestLevel()+1);
+  m_PtlCounter.m_ParticleSizeAtRank.resize(this->finestLevel()+1);
+
+  auto lf_GetParticleOffsetOfProcessor = [&](const long& numParticles,
+                                             unsigned long long& offset,
+                                             unsigned long long& sum)  -> void
+  {
+    std::vector<long> result(m_PtlCounter.m_MPISize,  0);
+    amrex::ParallelGather::Gather (numParticles, result.data(), -1, amrex::ParallelDescriptor::Communicator());
+
+    sum = 0;
+    offset = 0;
+    for (int i=0;  i<result.size();  i++) {
+      sum +=  result[i];
+      if ( i < m_PtlCounter.m_MPIRank)
+        offset +=  result[i];
+    }
+  };
+
+  for (auto currentLevel = 0; currentLevel <= this->finestLevel(); currentLevel++)
+    {
+      long numParticles = 0; // numParticles in this processor
+
+      //for (ParIter pti(*this, currentLevel); pti.isValid(); ++pti) {
+      for (ParConstIterType pti(*this, currentLevel); pti.isValid(); ++pti) {
+        auto numParticleOnTile = pti.numParticles();
+        numParticles += numParticleOnTile;
+      }
+
+      unsigned long long offset=0; // offset of this level
+      unsigned long long sum=0; // numParticles in this level (sum from all processors)
+      lf_GetParticleOffsetOfProcessor(numParticles, offset,  sum);
+
+      m_PtlCounter.m_ParticleCounterByLevel[currentLevel] = sum;
+      m_PtlCounter.m_ParticleOffsetAtRank[currentLevel] = offset;
+      m_PtlCounter.m_ParticleSizeAtRank[currentLevel] = numParticles;
+
+      // adjust offset, it should be numbered after particles from previous levels
+      for (auto lv=0; lv<currentLevel; lv++)
+        {
+          m_PtlCounter.m_ParticleOffsetAtRank[currentLevel] += m_PtlCounter.m_ParticleCounterByLevel[lv];
+        }
+
+      m_PtlCounter.m_Total += sum;
+    }
+}
+
+AMReX_PtlCounter m_PtlCounter;
+#endif // AMREX_PTL_OPENPMD_API_H
+
+