Handling interrupts in data processing of data in which only a portion of a function has been processed

A method of processing data comprising: processing a function using a processor operable to perform a plurality of functions, the processor having interrupts enabled; receiving an interrupt at the processor; suspending processing of the function; accessing at least one control parameter, the at least one control parameter indicating whether processing of the function should be resumed from the point where it was interrupted or whether the function should be repeated following the interrupt; following completion of the interrupt continuing processing of the function either at a start of the function or at a point at which it was interrupted dependent upon the control parameter. A function being an application, a thread, a system software routine, or multiple processing steps defined by software.