Miscellaneous instructions ========================== * nop() ``pass`` no operation. * wfi() Suspend execution in a low power state until an interrupt occurs. * cpsid(flags) set the Priority Mask Register - disable interrupts. * cpsie(flags) clear the Priority Mask Register - enable interrupts. Currently the ``cpsie()`` and ``cpsid()`` functions are partially implemented. They require but ignore the flags argument and serve as a means of enabling and disabling interrupts.