gistfile1.c

// main.c +13
// define memory location of NVIC
#define NVIC_INTERRUPTx_PRIORITY ( ( volatile unsigned char *) 0xE000E400 )

// +317
int get_interrupt_priority(int interrupt)
{
    if (interrupt < 240)    // ARM 有 240 種 external interrupt(0~239) 和16種inernal interrupt

        /* 根據 interrupt 設定 priority，這個常數宣告為 char*，故等同 array */
        return NVIC_INTERRUPTx_PRIORITY[interrupt]; 
    return -1;
}

// +296
unsigned int get_reload()
{
    return *(uint32_t *) 0xE000E014;    // access SysTick Register of Reload Value 
}

// +301
unsigned int get_current()
{
    return *(uint32_t *) 0xE000E018;    // access SysTick Register of Current Value 
}

// +306
unsigned int get_time()
{
    static unsigned int const *reload = (void *) 0xE000E014;
    static unsigned int const *current = (void *) 0xE000E018;
    static const unsigned int scale = 1000000 / configTICK_RATE_HZ;
    /* microsecond */

    return xTaskGetTickCount() * scale + (*reload - *current) / (*reload / scale);
}