systimer_irq_handler.c

#define IOREG(X)  (*(volatile uint32_t *) (X))

#define IRQ_PEND1         IOREG(0x2000B204)

#define SYST_CS  IOREG(0x20003000)
#define SYST_C0  IOREG(0x2000300C)
#define SYST_C1  IOREG(0x20003010)
#define SYST_C2  IOREG(0x20003014)
#define SYST_C3  IOREG(0x20003018)

#define IRQ_TIMER_C1  (1 << 1)
#define IRQ_TIMER_C3  (1 << 3)

static volatile int counter1;
static volatile int counter3;
static volatile int changed1;
static volatile int changed3;

static void __attribute__((interrupt("IRQ"))) irq_handler(void) {
    if (IRQ_PEND1 & IRQ_TIMER_C1) {
        counter1++;
        changed1 = 1;
        SYST_C1 = SYST_C1 + 960000;
        SYST_CS |= (1 << 1);
    }
    if (IRQ_PEND1 & IRQ_TIMER_C3) {
        counter3++;
        changed3 = 1;
        SYST_C3 = SYST_C3 + 720000;
        SYST_CS |= (1 << 3);
    }
}