qdp_dispatch.h

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#ifndef QDP_DISPATCH_H
#define QDP_DISPATCH_H
 
#include "qdp_diagnostics.h"
 
#include "qdp_config.h"
 
#if defined(QDP_USE_OMP_THREADS)
QDPXX_MESSAGE("QDP using OpenMP threading")
#include <omp.h>
namespace QDP {    
/* OpenMP threading version of the dispatch.*/
 
  
  inline
    int qdpNumThreads()
  {
    return omp_get_max_threads();
  }
 
 
  inline
    int qdpThreadNum()
  {
    return omp_get_thread_num();
  }
 
 
template<class Arg>
void dispatch_to_threads(int numSiteTable, Arg a, void (*func)(int,int,int, Arg*)){
   
 
#pragma omp parallel shared(numSiteTable, a)
    {
     
      int threads_num = omp_get_num_threads();
      int myId = omp_get_thread_num();
 
      int active_threads_num = threads_num > numSiteTable ? numSiteTable : threads_num;
 
      if( myId < numSiteTable ) {
          int low = (numSiteTable*myId)/active_threads_num;
 
          // NB: high can never be too high since for the last thread
          // myId + 1 = (threads_num - 1) + 1 = threads_num.
          // So numSiteTable*(myId+1) will always be a strict multiple of threads_num
          // and so truncation issues will not bite.
          // I am addig in the parentheses tho to force the precedence
          int high =(numSiteTable*(myId+1))/active_threads_num;
 
          func(low, high, myId, &a);
      }
    }
}
}
 
#else 
 
#if defined(QDP_USE_QMT_THREADS)
QDPXX_MESSAGE("QDP using QMT threading")
 
 /* QMT threading version of the dispatch. Call the qmt_call routine
     with userfunc, numSiteTable, and argument */
 
#include <qmt.h>
 
namespace QDP { 
 
 inline
   int qdpNumThreads()
 {
   return qmt_num_threads();
 }
 
 inline
   int qdpThreadNum()
 {
   return qmt_thread_num();
 }
 
 
template<class Arg>
void dispatch_to_threads(int numSiteTable, Arg a, void (*func)(int,int,int,Arg*)){
 
   qmt_call((qmt_userfunc_t)func, numSiteTable, &a);
 
}
}
#else
namespace QDP {
 
 inline
 int qdpNumThreads()
 {
   return 1;
 }
 
 inline
 int qdpThreadNum()
 {
   return 0;
 }
 
template<class Arg>
void dispatch_to_threads(int numSiteTable, Arg a, void (*func)(int,int,int,Arg*)){
   
  int low = 0;
  int high = numSiteTable;
   
  func(low, high, 0, &a);
    
 }
 
} 
#endif
#endif
 
#endif