Multitasking microcontroller for controlling the physical layer of a network interface card and method of operation

A processing system comprising:

• a data processor;
• and
• a network interface card for coupling said processing system to a data network, said network interface card comprising an apparatus for controlling a physical layer interface of said network interface card in real time, said apparatus comprising:
• a first memory capable of storing a multitasking control program, said multitasking control program comprising a main routine and a plurality of subroutines sequentially callable by said main routine;
• a second memory capable of storing a plurality of multitasking vectors associated with said multitasking control program;
• and
• a microcontroller capable of executing said multitasking control program;
• wherein program execution control is transferred from said main routine to a first one of said plurality of subroutines when said first subroutine is called by said main routine;
• wherein said first subroutine, upon encountering a decision point in said first subroutine that is not yet capable of being decided, updates a first one of said plurality of multitasking vectors associated with said first subroutine with an address of said decision point and transfers program execution control back to said main routine;
• and
• wherein the main routine, after sequentially transferring program execution control to each remaining subroutine in the plurality of subroutines, again transfers program execution control from the main routine to the first subroutine at the address of the decision point contained in the first multitasking vector.

For use in a network interface card having a physical layer interface controllable by a microcontroller embedded therein, a method of operating the microcontroller comprising the steps of:

• storing a multitasking control program, the multitasking control program comprising a main routine and a plurality of subroutines sequentially callable by the main routine;
• storing a plurality of multitasking vectors associated with the multitasking control program;
• and
• executing the multitasking control program in a microcontroller;
• transferring program execution control from the main routine to a first one of the plurality of subroutines when the first subroutine is called by the main routine;
• when the first subroutine encounters a decision point in the first subroutine that is not yet capable of being decided, updating a first one of the plurality of multitasking vectors associated with the first subroutine with an address of the decision point;
• transferring program execution control back to the main routine;
• and
• after sequentially transferring program execution control from the main routine to each remaining subroutine in the plurality of subroutines, again transferring program execution control from the main routine to the first subroutine at the address of the decision point contained in the first multitasking vector.