A method and apparatus within a processing system is provided for
associating shadow register sets with interrupt routines. The invention
includes a vector generator that receives interrupts, and generates
exception vectors to call interrupt routines that correspond to the
interrupts. The exception vector considers the type of interrupt and the
priority level of the interrupt when selecting the exception vector.
Shadow set mapping logic is coupled to the vector generator. The mapping
logic contains a number of fields that correspond to the different
exception vectors that may be generated. The fields are programmable by
kernel mode instructions, and contain data mapping each field to one of a
number of shadow register sets. When an interrupt occurs, the vector
generator generates a corresponding exception vector. In addition, the
shadow set mapping logic looks at the field corresponding to the
exception vector, and retrieves the data stored therein. The data is used
to switch to one of the shadow register sets for use by an interrupt
routine. Upon return from the interrupt routine, the previously used
register set is selected.