OMP.h

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// # Copyright (C) 1993,1994,1995,1996,2000,2003
// # Associated Universities, Inc. Washington DC, USA.
// #
// # This library is free software; you can redistribute it and/or modify it
// # under the terms of the GNU Library General Public License as published by
// # the Free Software Foundation; either version 2 of the License, or (at your
// # option) any later version.
// #
// # This library is distributed in the hope that it will be useful, but WITHOUT
// # ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
// # FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Library General Public
// # License for more details.
// #
// # You should have received a copy of the GNU Library General Public License
// # along with this library; if not, write to the Free Software Foundation,
// # Inc., 675 Massachusetts Ave, Cambridge, MA 02139, USA.
// #
// # Correspondence concerning AIPS++ should be addressed as follows:
// #        Internet email: casa-feedback@nrao.edu.
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#ifndef CASA_OS_OMP_H
#define CASA_OS_OMP_H
 
#include <casacore/casa/aips.h>
#ifdef _OPENMP
#include <omp.h>
#endif
 
namespace casacore {
namespace OMP {
 
// Get the maximum number of threads.
// OpenMP sets it to the env.var. OMP_NUM_THREADS. If undefined, it is
// the number of cores.
// If OpenMP is not used, 1 is returned.
inline uInt maxThreads() {
#ifdef _OPENMP
  return omp_get_max_threads();
#else
  return 1;
#endif
}
// Backward
uInt nMaxThreads();
 
// Set the number of threads to use. Note it can be overridden
// for a parallel section by 'omp parallel num_threads(n)'.
// Nothing is done if OpenMP is not used.
#ifdef _OPENMP
inline void setNumThreads(uInt n) { omp_set_num_threads(n); }
#else
inline void setNumThreads(uInt) {}
#endif
 
// Get the number of threads used in a parallel piece of code.
// If OpenMP is not used, 1 is returned.
inline uInt numThreads() {
#ifdef _OPENMP
  return omp_get_num_threads();
#else
  return 1;
#endif
}
 
// Get the thread number (0 till numThreads).
// If OpenMP is not used, 0 is returned.
inline uInt threadNum() {
#ifdef _OPENMP
  return omp_get_thread_num();
#else
  return 0;
#endif
}
 
// Set if nested parallel sections are possible or not.
// Nothing is done if OpenMP is not used.
#ifdef _OPENMP
inline void setNested(Bool nest) { omp_set_nested(nest); }
#else
inline void setNested(Bool) {}
#endif
 
// Test if nested parallel sections are possible.
// If OpenMP is not used, false is returned.
inline bool nested() {
#ifdef _OPENMP
  return omp_get_nested();
#else
  return false;
#endif
}
 
}  // namespace OMP
}  // namespace casacore
 
#endif