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/// @file G4MPIrandomSeedGenerator.cc
/// @brief An implementation of random number seed distribution

#include "mpi.h"
#include "Randomize.hh"
#include "G4MPImanager.hh"
#include "G4MPIrandomSeedGenerator.hh"

// --------------------------------------------------------------------------
G4MPIrandomSeedGenerator::G4MPIrandomSeedGenerator()
  : G4VMPIseedGenerator()
{
  GenerateSeeds();
}

// --------------------------------------------------------------------------
G4MPIrandomSeedGenerator::~G4MPIrandomSeedGenerator()
{
}

// --------------------------------------------------------------------------
G4bool G4MPIrandomSeedGenerator::CheckDoubleCount()
{
  G4MPImanager* g4mpi = G4MPImanager::GetManager();

  G4int nsize = g4mpi-> GetSize();

  for ( G4int i = 0; i < nsize; i++ ) {
    for ( G4int j = 0; j < nsize; j++ ) {
      if( (i != j) && (seed_list_[i] == seed_list_[j]) ) {
        G4double x = G4UniformRand();
        seed_list_[j] = G4long(x*LONG_MAX);
        return false;
      }
    }
  }

  return true;
}

// --------------------------------------------------------------------------
void G4MPIrandomSeedGenerator::GenerateSeeds()
{
  G4MPImanager* g4mpi = G4MPImanager::GetManager();

  G4int nsize = g4mpi-> GetSize();

  seed_list_.clear();

  for ( G4int i = 0; i < nsize; i++ ) {
    G4double x = G4UniformRand();
    G4int seed = G4long(x*LONG_MAX);
    seed_list_.push_back(seed);
  }

  while(! CheckDoubleCount()) {
    continue;
  }
}
