/*
 * timing.c
 *
 *  Created on: 07.12.2009
 *      Author: adamczew
 *
 */



#include "timing.h"
#include "errno.h"

/*#define _TIMING_DEBUG_ 1*/

static cycles_t StartTime=0;

static cycles_t DeltaTime=0;

static double CyclesToSeconds=0;

static struct timespec ClockStart, ClockStop, ClockDiff;


void MbsPextest_TimerInit()
{
	double mhz=MbsPextest_Linux_get_cpu_mhz();
	if(mhz)
	{
		CyclesToSeconds=1.0e-6 / mhz;
		printf("MbsPextest_TimerInit finds  %lf Mhz CPU => %e s/cycle \n", mhz, CyclesToSeconds);
	}
	else
	{
		printf("MbsPextest_TimerInit could not evaluate CPU frequency!!\n");
		CyclesToSeconds=0;
	}
	StartTime=0;
	DeltaTime=0;
}

void MbsPextest_TimerStart()
{
	StartTime=MbsPextest_GetCycles();
}

double MbsPextest_TimerDelta()
{
	DeltaTime=MbsPextest_GetCycles()-StartTime;
	return DeltaTime*CyclesToSeconds;
}


#if defined (__x86_64__) || defined(__i386__)
/* Note: only x86 CPUs which have rdtsc instruction are supported. */
   inline cycles_t MbsPextest_GetCycles()
   {
      unsigned low, high;
      unsigned long long val;
      asm volatile ("rdtsc" : "=a" (low), "=d" (high));
      val = high;
      val = (val << 32) | low;
      return val;
   }
#elif defined(__PPC__) || defined(__PPC64__)
/* Note: only PPC CPUs which have mftb instruction are supported. */
/* PPC64 has mftb */
   inline cycles_t MbsPextest_GetCycles()
   {
      cycles_t ret;

      asm volatile ("mftb %0" : "=r" (ret) : );
      return ret;
   }
#elif defined(__ia64__)
/* Itanium2 and up has ar.itc (Itanium1 has errata) */
   inline cycles_t MbsPextest_GetCycles()
   {
      cycles_t ret;
      asm volatile ("mov %0=ar.itc" : "=r" (ret));
      return ret;
   }

#else

#endif



double MbsPextest_Linux_get_cpu_mhz()
{
   FILE* f;
   char buf[256];
   double mhz = 0.0;

   f = fopen("/proc/cpuinfo","r");
   if (!f)
      return 0.0;
   while(fgets(buf, sizeof(buf), f)) {
      double m;
      int rc;
      rc = sscanf(buf, "cpu MHz : %lf", &m);
      if (rc != 1) {   // PPC has a different format
         rc = sscanf(buf, "clock : %lf", &m);
         if (rc != 1)
            continue;
      }
      if (mhz == 0.0) {
         mhz = m;
         continue;
      }
      if (mhz != m) {
          printf("Conflicting CPU frequency values detected: %lf != %lf\n", mhz, m);
          return 1000.0;
      }
   }
   fclose(f);
   return mhz;
}


/* resets start time value of system realtime clock*/
void MbsPextest_ClockStart()
{
  int lerr;
	if(clock_gettime(CLOCK_REALTIME, &ClockStart))
	  {
	    lerr=errno;
	    printf("clock_gettime error %d (%s)in MbsPextest_ClockStart", lerr, strerror(lerr));
	  }
#ifdef	_TIMING_DEBUG_
	printf("ClockStart got time %d seconds, %ul ns\n",ClockStart.tv_sec, ClockStart.tv_nsec);
#endif

}

/* return value is seconds since ClockStart*/
double MbsPextest_ClockDelta()
{
    int lerr;
    double rev=0;
	if(clock_gettime(CLOCK_REALTIME, &ClockStop))
	      {
	        lerr=errno;
	        printf("clock_gettime error %d  (%s) in MbsPextest_ClockDelta", lerr, strerror(lerr));
	      }

	MbsPextest_tsDiff(&ClockDiff,&ClockStart,&ClockStop);
	rev=MbsPextest_tsAsSeconds(&ClockDiff);
#ifdef  _TIMING_DEBUG_
    printf("ClockDelta got time %d seconds, %ul ns\n",ClockStop.tv_sec, ClockStop.tv_nsec);
    printf("ClockDelta got delta time %d seconds, %ul ns -> as seconds=%e\n",ClockDiff.tv_sec, ClockDiff.tv_nsec, rev);
#endif
	return rev;
}




/* these little helpers stolen from mprace lib:*/
void MbsPextest_tsDiff(struct timespec *diff, struct timespec* begin, struct timespec* end) {
	if (end->tv_nsec < begin->tv_nsec) {
		diff->tv_nsec = (end->tv_nsec + 1000000000L) - begin->tv_nsec;
		diff->tv_sec = end->tv_sec - begin->tv_sec - 1;
	}
	else {
		diff->tv_nsec = end->tv_nsec - begin->tv_nsec;
		diff->tv_sec = end->tv_sec - begin->tv_sec;
	}

	if (diff->tv_nsec > 1000000000L) {
		diff->tv_sec++;
		diff->tv_nsec -= 1000000000L;
	}

	return;
}

double MbsPextest_tsAsSeconds(struct timespec* ts) {
	double f;
	f = (double)( ts->tv_sec );
	f += (double)(ts->tv_nsec) * 1E-9;
	return f;
}


void MbsPextest_ShowRate(const char* description, double mem, double timeseconds)
{
	double rate=0;
	if(timeseconds)
		rate=mem/timeseconds;
	printf("Show Rate: %s - time:%e s for %e bytes, speed is %e bytes/s\n", description, timeseconds, mem,rate);

}