hash_functions.cu

#include <cuhash/hash_table.h>
#include <cuhash/debugging.h>
#include <cassert>
#include <random>

namespace cuhash {
  
std::random_device random_dev;

std::mt19937 random_engine(random_dev());
std::uniform_int_distribution<unsigned> uint_distribution;

unsigned generate_random_uint32(){
  return uint_distribution(random_engine);
}

void GenerateFunctions(const unsigned  N,
                       const unsigned  num_keys,
                       const unsigned *d_keys,
                       const unsigned  table_size,
                             uint2    *constants) {
  bool regenerate = true;

  while (regenerate) {
    regenerate = false;

    // Generate a set of hash function constants for this build attempt.
    for (unsigned i = 0 ; i < N; ++i) {
      // uint_distribution(random_engine) % kPrimeDivisor;
      // genrand_int32() % kPrimeDivisor;
      unsigned new_a = generate_random_uint32() % kPrimeDivisor;
      constants[i].x = (1 > new_a ? 1 : new_a);
      constants[i].y = generate_random_uint32() % kPrimeDivisor;
    }

#ifdef FORCEFULLY_GENERATE_NO_CYCLES
    // Ensure that every key gets N different slots.
    regenerate = CheckAssignedSameSlot(N, num_keys, d_keys, table_size, constants);
#endif
  }


#ifdef TAKE_HASH_FUNCTION_STATISTICS
  // Examine how well distributed the items are.
  TakeHashFunctionStatistics(num_keys, d_keys, table_size, constants, N);
#endif
}

}; // namespace CuckooHashing