#define	STSR_CSR 	(*(volatile uint32_t *)0xE000E010)
#define	STSR_RVR 	(*(volatile uint32_t *)0xE000E014)
#define	STSR_CRV 	(*(volatile uint32_t *)0xE000E018)
#define	STSR_CALIB 	(*(volatile uint32_t *)0xE000E01C)

__attribute__((optimize("O2")))
static unsigned short measureCPUfreq (void)
{
	uint16_t i;

	STSR_RVR = 0x00FFFFFF;  //reloaded value
	STSR_CRV = 0x1;  		//reset the counter
	STSR_CSR = 0x5;

	for(i=0; i<64; i++)  // 64 x 16 Mops
	{
		// Number of clock edge
		while(!(STSR_CSR&0x10000)); // 16 Mops
	}

  	return (ANSW_OK);
}