From 071cbecfc456f48eae76a9e5d0ace2708b31b33c Mon Sep 17 00:00:00 2001
From: Thomas Purcell <purcell@fhi-berlin.mpg.de>
Date: Sat, 9 May 2020 11:00:28 +0200
Subject: [PATCH] Add MPI intraface class
Start parallelzationo
---
src/mpi_interface/MPI_Interface.cpp | 14 ++++++++++
src/mpi_interface/MPI_Interface.hpp | 41 +++++++++++++++++++++++++++++
2 files changed, 55 insertions(+)
create mode 100644 src/mpi_interface/MPI_Interface.cpp
create mode 100644 src/mpi_interface/MPI_Interface.hpp
diff --git a/src/mpi_interface/MPI_Interface.cpp b/src/mpi_interface/MPI_Interface.cpp
new file mode 100644
index 00000000..d8741ab1
--- /dev/null
+++ b/src/mpi_interface/MPI_Interface.cpp
@@ -0,0 +1,14 @@
+MPI_Interface::MPI_Interface() : boost::mpi::communicator()
+{}
+
+std::array<int, 2> MPI_Interface::get_start_end_from_list(int size, int start)
+{
+ int els_per_rank = size / size();
+ int remaineder = size % size();
+
+ std::array<int, 2> start_end;
+ start_end[0] = start + els_per_rank * rank() + std::min(rank(), remaineder);
+ start_end[1] = start + els_per_rank * (rank() + 1) + std::min(rank() + 1, remaineder);
+
+ return start_end;
+}
diff --git a/src/mpi_interface/MPI_Interface.hpp b/src/mpi_interface/MPI_Interface.hpp
new file mode 100644
index 00000000..7654105f
--- /dev/null
+++ b/src/mpi_interface/MPI_Interface.hpp
@@ -0,0 +1,41 @@
+#ifndef SISSO_MPI_INTERFACE
+#define SISSO_MPI_INTERFACE
+
+#include <boost/mpi.hpp>
+#include <array>
+
+extern boost::mpi::environment env;
+namespace mpi = boost::mpi;
+
+// Augment the boost mpi communicator class with some other useful data
+/**
+ * @brief Augment the boost MPI communicator class with some other useful data
+ * @details MPI communicator used to transfer data throughout the cell.
+ *
+ */
+class MPI_Interface : public boost::mpi::communicator
+{
+public:
+ /**
+ * @brief Constructor for the MPI_Interface
+ */
+ MPI_Interface();
+
+ std::array<int, 2> get_start_end_from_list(int size, int start);
+
+ /**
+ * @brief Unique int tag generator
+ *
+ * @param[in] procSend sending process
+ * @param[in] procRecv receiving process
+ * @param[in] maxOffest number of different communication processes possible between two processes within the same operation
+ * @param[in] offest the assigned offset corresponding to a single communication within the same operation
+ *
+ * @return A unique tag to send information between two processes
+ */
+ int cantorTagGen(unsigned int procSend, unsigned int procRecv, unsigned int maxOffest, unsigned int offest) { return (int((procSend + procRecv) * (procSend + procSend +1) / 2) + procRecv) * maxOffest + offest; }
+
+
+};
+
+#endif
\ No newline at end of file
--
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