/*****************************************************************************

 * PAPI_perror converts PAPI error codes to strings,it fills the string      *

 * destination with the error message corresponding to the error code.       *

 * The function copies length worth of the error description string          *

 * corresponding to code into destination. The resulting string is always    *

 * null terminated. If length is 0, then the string is printed on stderr.    *

 * PAPI_strerror does similar but it just returns the corresponding          *

 * error string from the code.                                               *

 *****************************************************************************/

#include <stdio.h>

#include <stdlib.h>

#include "papi.h" /* This needs to be included every time you use PAPI */

int main()

{

   int retval;

   int EventSet = PAPI_NULL;

   char error_str[PAPI_MAX_STR_LEN];

   /****************************************************************************

   *  This part initializes the library and compares the version number of the *

   * header file, to the version of the library, if these don't match then it  *

   * is likely that PAPI won't work correctly.If there is an error, retval     *

   * keeps track of the version number.                                        *

   ****************************************************************************/

   if((retval = PAPI_library_init(PAPI_VER_CURRENT)) != PAPI_VER_CURRENT )

   {

      exit(1);

   }

   if ((retval = PAPI_create_eventset(&EventSet)) != PAPI_OK)

   {

      fprintf(stderr, "PAPI error %d: %s\n",retval,PAPI_strerror(retval));

      exit(1);

   }     

   /* Add Total Instructions Executed to our EventSet */

   if ((retval = PAPI_add_event(EventSet, PAPI_TOT_INS)) != PAPI_OK)

   {

      PAPI_perror( "PAPI_add_event" );

      exit(1);

   }

   /* Start counting */

   if ((retval = PAPI_start(EventSet)) != PAPI_OK)

   {

      PAPI_perror( "PAPI_start" );

      exit(1);

   }

  /* We are trying to start the  counter which has already been started, 

     and this will give an error which will be passed to PAPI_perror via 

     retval and the function will then display the error string on the 

     screen.

   */ 

   if ((retval = PAPI_start(EventSet)) != PAPI_OK)

   {

      PAPI_perror( "PAPI_start" );

   }

   /* The function PAPI_strerror returns the corresponding error string 

      from the error code */ 

   if ((retval = PAPI_start(EventSet)) != PAPI_OK)

   {

      printf("%s\n",PAPI_strerror(retval));

   }

   /* finish using PAPI and free all related resources 

     (this is optional, you don't have to use it 

   */

   PAPI_shutdown (); 

   exit(0);

}