external/mpi_utils.h

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#ifndef MPI_UTILS_H
#define MPI_UTILS_H
///
/// @file mpi_utils.h
/// @brief Overloaded utility functions to convert between arbitrary C/C++ 
///        types and MPI types, custom typedefs for cstdlib types like size_t,
///        and a wrapper for MPI_Pack_Size
///

#include <iostream>
#include <cstdlib>
#include <stdint.h>
#include <mpi.h>

//
// Overloaded functions for getting corresponding MPI types for C types.
//
inline MPI_Datatype mpi_typeof(char)                       {return MPI_CHAR;}
inline MPI_Datatype mpi_typeof(signed short)               {return MPI_SHORT;}
inline MPI_Datatype mpi_typeof(signed int)                 {return MPI_INT;}
inline MPI_Datatype mpi_typeof(signed long)                {return MPI_LONG;}
inline MPI_Datatype mpi_typeof(unsigned char)              {return MPI_UNSIGNED_CHAR;}
inline MPI_Datatype mpi_typeof(unsigned short)             {return MPI_UNSIGNED_SHORT;}
inline MPI_Datatype mpi_typeof(unsigned)                   {return MPI_UNSIGNED;}
inline MPI_Datatype mpi_typeof(unsigned long)              {return MPI_UNSIGNED_LONG;}
inline MPI_Datatype mpi_typeof(signed long long)           {return MPI_LONG_LONG_INT;}
inline MPI_Datatype mpi_typeof(double)                     {return MPI_DOUBLE;}
inline MPI_Datatype mpi_typeof(long double)                {return MPI_LONG_DOUBLE;}
inline MPI_Datatype mpi_typeof(std::pair<int,int>)         {return MPI_2INT;}
inline MPI_Datatype mpi_typeof(std::pair<float,int>)       {return MPI_FLOAT_INT;}
inline MPI_Datatype mpi_typeof(std::pair<double,int>)      {return MPI_DOUBLE_INT;}
inline MPI_Datatype mpi_typeof(std::pair<long double,int>) {return MPI_LONG_DOUBLE_INT;}
inline MPI_Datatype mpi_typeof(std::pair<short,int>)       {return MPI_SHORT_INT;}

// 
// Handy datatypes for stdlib datatypes
// @todo these won't work in heterogeneous environments, as it's tied to the machine type.
// 
#define MPI_SIZE_T      (mpi_typeof(size_t()))
#define MPI_INTPTR_T    (mpi_typeof(intptr_t()))
#define MPI_UINTPTR_T   (mpi_typeof(uintptr_t()))

///
/// Expression-ifies the overly C-ish MPI_Pack_size function.  Just returns 
/// the size instead of requring a temporary.
///
inline int mpi_packed_size(int count, MPI_Datatype type, MPI_Comm comm) {
  int size;
  MPI_Pack_size(count, type, comm, &size);
  return size;
}

///
/// PMPI binding for mpi_packed_size().
///
inline int pmpi_packed_size(int count, MPI_Datatype type, MPI_Comm comm) {
  int size;
  PMPI_Pack_size(count, type, comm, &size);
  return size;
}


#endif // MPI_UTILS_H