ldr \irqnr, [\base, #(AT91_AIC_IVR - AT91_AIC)] @ read IRQ vector register: de-asserts nIRQ to processor (and clears interrupt)
ldr \irqstat, [\base, #(AT91_AIC_ISR - AT91_AIC)] @ read interrupt source number
teq \irqstat, #0 @ ISR is 0 when no current interrupt, or spurious interrupt
ldr \irqnr, [\base, #(AT91_AIC_IVR - AT91_AIC)] @ read IRQ vector register: de-asserts nIRQ to processor (and clears interrupt)
ldr \irqstat, [\base, #(AT91_AIC_ISR - AT91_AIC)] @ read interrupt source number
teq \irqstat, #0 @ ISR is 0 when no current interrupt, or spurious interrupt