/* clock.c
 * Support file for nvptx in newlib.
 */
#include <time.h>

/* PTX's clock64 is a cycle count, whose frequency varies with the GPU's
   operating frequency, which may be boosted or thermally throttled at
   run-time.  The value provided is suitable for relative timings, but
   must be corrected [by the host] for accurate elapsed/wall clock times.  */
/* NVidia RTX-2080 Super	1650-1815 MHz.  */
/* NVidia GTX-1070		1506-1683 MHz.  */
/* NVidia RTX-2070		1410 MHz.  */
/* NVidia GTX-1050 Ti		1290-1392 MHz.  */
/* NVidia Quadro P400		1228-1252 MHz.  */
/* NVidia GTX 660		823 MHz.   */

#define NVPTX_MHZ 1250

clock_t
clock ()
{
  unsigned long long now;
  asm volatile("mov.u64 %0, %%clock64;" : "=r"(now));
  return now/((NVPTX_MHZ*1000000)/CLOCKS_PER_SEC);
}