#ifndef GRID_PERFCOUNT_H
#define GRID_PERFCOUNT_H

#include <sys/time.h>
#include <ctime>
#include <chrono>
#include <string.h>
#include <sys/ioctl.h>
#include <syscall.h>
#include <linux/perf_event.h>

namespace Grid {


static long perf_event_open(struct perf_event_attr *hw_event, pid_t pid,
			    int cpu, int group_fd, unsigned long flags)
{
  int ret;

  ret = syscall(__NR_perf_event_open, hw_event, pid, cpu,
		group_fd, flags);
  return ret;
}


class PerformanceCounter {
private:
  typedef struct { 
  public:
    uint32_t type;
    uint64_t config;
    const char *name;
  } PerformanceCounterConfig; 
  
  static const PerformanceCounterConfig PerformanceCounterConfigs [];

public:

  enum PerformanceCounterType {
    CPUCYCLES=0,
    INSTRUCTIONS,
    //    STALL_CYCLES,
    CACHE_REFERENCES,
    CACHE_MISSES,
    L1D_READ_MISS,
    L1D_READ_ACCESS,
    L1D_WRITE_MISS,
    L1D_WRITE_ACCESS,
    L1D_PREFETCH_MISS,
    L1D_PREFETCH_ACCESS,
    LL_READ_MISS,
    //    LL_READ_ACCESS,
    LL_WRITE_MISS,
    LL_WRITE_ACCESS,
    LL_PREFETCH_MISS,
    LL_PREFETCH_ACCESS,
    L1I_READ_MISS,
    L1I_READ_ACCESS,
    PERFORMANCE_COUNTER_NUM_TYPES
  };

public:
    
  int PCT;

  struct perf_event_attr pe;
  long long count;
  int fd;
  uint64_t elapsed;
  uint64_t begin;

  static int NumTypes(void){ 
    return PERFORMANCE_COUNTER_NUM_TYPES;
  }

  PerformanceCounter(int _pct) {
    assert(_pct>=0);
    assert(_pct<PERFORMANCE_COUNTER_NUM_TYPES);
    fd=-1;
    count=0;
    PCT =_pct;
    Open();
  }
  void Open(void) 
  {
    memset(&pe, 0, sizeof(struct perf_event_attr));
    pe.size = sizeof(struct perf_event_attr);

    pe.disabled = 1;
    pe.exclude_kernel = 1;
    pe.exclude_hv = 1;
    pe.inherit    = 1;

    pe.type  = PerformanceCounterConfigs[PCT].type;
    pe.config= PerformanceCounterConfigs[PCT].config;
    const char * name = PerformanceCounterConfigs[PCT].name;
    fd = perf_event_open(&pe, 0, -1, -1, 0); // pid 0, cpu -1 current process any cpu. group -1
    if (fd == -1) {
      fprintf(stderr, "Error opening leader %llx for event %s\n", pe.config,name);
      perror("Error is");
    }
  }

  void Start(void)
  {
    if ( fd!= -1) {
      ioctl(fd, PERF_EVENT_IOC_RESET, 0);
      ioctl(fd, PERF_EVENT_IOC_ENABLE, 0);
    }
    begin  =__rdtsc();
  }

  void Stop(void) {
    count=0;
    if ( fd!= -1) {
      ioctl(fd, PERF_EVENT_IOC_DISABLE, 0);
      ::read(fd, &count, sizeof(long long));
    }
    elapsed = __rdtsc() - begin;
  }
  void Report(void) {
    printf("%llu cycles %s = %20llu\n", elapsed , PerformanceCounterConfigs[PCT].name, count);
  }

  ~PerformanceCounter()
  {
    close(fd);
  }

};

}
#endif