timers.h

#ifndef TIMERS_H_
#define TIMERS_H_

#include <cinttypes>
#include <ctime>

/*
USAGE:
    TIMESTAMP_INIT
    TIMESTAMP_T t1, t2;

    GET_TIMESTAMP(t1);
    GET_TIMESTAMP(t2);
    printf("Elapsed time in nanoseconds: %lu\n", ELAPSED_NSEC(t1, t2));
*/

#define RDTSC 1
#define RDTSCP 2
#define GET_TIME_MONOTONIC 3

#define LOG_FUNCTION GET_TIME_MONOTONIC

#if LOG_FUNCTION == RDTSC
#define TIMESTAMP_INIT HRT_INIT
    #define TIMESTAMP_T HRT_TIMESTAMP_T
    #define GET_TIMESTAMP(t) HRT_GET_TIMESTAMP_UNSAFE(t)
    #define ELAPSED_NSEC(t1, t2) HRT_GET_INTERVAL_NSEC(t1, t2)
#elif LOG_FUNCTION == RDTSCP
#define TIMESTAMP_INIT HRT_INIT
    #define TIMESTAMP_T HRT_TIMESTAMP_T
    #define GET_TIMESTAMP(t) HRT_GET_TIMESTAMP_SAFE(t)
    #define ELAPSED_NSEC(t1, t2) HRT_GET_INTERVAL_NSEC(t1, t2)
#elif LOG_FUNCTION == GET_TIME_MONOTONIC
#define TIMESTAMP_INIT
#define TIMESTAMP_T struct timespec
#define GET_TIMESTAMP(t) clock_gettime(CLOCK_MONOTONIC, &t)
#define ELAPSED_NSEC(t1, t2) t2.tv_nsec-t1.tv_nsec
#endif

#define UINT32_T uint32_t
#define UINT64_T uint64_t

typedef struct {
    UINT32_T l;
    UINT32_T h;
} x86_64_timeval_t;

#define HRT_TIMESTAMP_T x86_64_timeval_t

#define HRT_GET_TIMESTAMP_UNSAFE(t1)  __asm__ __volatile__ ("rdtsc" : "=a" (t1.l), "=d" (t1.h));
#define HRT_GET_TIMESTAMP_SAFE(t1)  __asm__ __volatile__ ("rdtscp" : "=a" (t1.l), "=d" (t1.h));

#define HRT_GET_ELAPSED_TICKS(t1, t2, numptr)   *numptr = (((( UINT64_T ) t2.h) << 32) | t2.l) - \
                                                          (((( UINT64_T ) t1.h) << 32) | t1.l);

/* global timer frequency in Hz */
unsigned long long g_timerfreq;

#define HRT_CALIBRATE do {  \
  static volatile HRT_TIMESTAMP_T t1, t2; \
  static volatile UINT64_T elapsed_ticks, min = (UINT64_T)(~0x1); \
  int notsmaller=0; \
  while(notsmaller<3) { \
    printf("Calibrating\n");\
    HRT_GET_TIMESTAMP_SAFE(t1); \
    sleep(1);  \
    GET_TIMESTAMP(t2); \
    HRT_GET_ELAPSED_TICKS(t1, t2, &elapsed_ticks); \
    notsmaller++; \
    if(elapsed_ticks<min) { \
      min = elapsed_ticks; \
      notsmaller = 0; \
    } \
  } \
  g_timerfreq = min; \
  printf("freq %llu\n", g_timerfreq); \
} while(0);

#define HRT_INIT HRT_CALIBRATE

#define HRT_GET_TIME(t1, time) time = (((( UINT64_T ) t1.h) << 32) | t1.l)

#define HRT_GET_NSEC(ticks) (unsigned long) (1e9*(double)ticks/(double)g_timerfreq)

#define HRT_GET_INTERVAL_NSEC(t1, t2) \
    HRT_GET_NSEC(  (\
    (((( UINT64_T ) t2.h) << 32) | t2.l) - \
    (((( UINT64_T ) t1.h) << 32) | t1.l) \
    ))

#endif /* TIMERS_H_ */