//------------------------------------------------------------------------------------------------------------------------------
// Samuel Williams
// SWWilliams@lbl.gov
// Lawrence Berkeley National Lab
//------------------------------------------------------------------------------------------------------------------------------
#include <stdint.h>
uint64_t CycleTime(){
  #ifndef __has_builtin
  #define __has_builtin(x) 0
  #endif 

  #if !defined(USE_CYCLE_COUNTER)
    return 0;
  #elif __has_builtin(__builtin_readcyclecounter)
    return __builtin_readcyclecounter();
  #else
    uint64_t lo, hi;
    __asm__ __volatile__ ("rdtsc" : "=a" (lo), "=d" (hi));
    return( (((uint64_t)hi) << 32) | ((uint64_t)lo) );
  #endif
}