Interrupt service routine processing method for e.g. set-top box, involves starting counter while processor is operated in non-secured mode and returning processor to secured mode to pursue process execution when counter attains end value

摘要

The method involves initializing a counter (12) to a starting value, when an interrupt service routine associated to an interrupt service routine sub-program executable in a non-secured mode is sent to a processor (1) during the execution of a process by the processor in a secured mode. The counter is started while the processor is operated in the non-secured mode for executing the sub-program associated to the interrupt service routine. The processor is returned to the secured mode for pursuing the execution of the process, when the counter attains an end value. An independent claim is also included for a processor adapted to operate in one of two modes.