Mechanism for on-the-fly handling of unaligned memory accesses

For use with a data processing system, wherein an access to memory must conform with prescribed memory boundary conditions, a method of handling an exception generated as a result of encountering an instruction containing an unaligned memory access code, that does not conform with said prescribed memory boundary conditions, said method comprising the steps of:

• (a) saving contents of all processor registers in an exception stack frame;
• (b) decoding said instruction to identify which processor register is associated with said unaligned memory access code and with which data is to be interfaced;
• (c) interfacing said data with that processor register of said exception stack frame, into which contents of said processor register identified in step (b) were saved in step (a);
• (d) replacing contents of said all processor registers with contents their associated processor registers in said exception stack frame;
• and
• (e) proceeding to the next instruction following said instruction containing said unaligned memory access code.

For use with a communication control processor of a data communication system, wherein digital data transported over a communication link is stored and read out of memory, and wherein access to said memory by said communication control processor must conform with prescribed memory boundary conditions, a method of handling an unaligned address exception generated as a result of encountering an instruction containing an unaligned memory access code, that does not conform with said prescribed memory boundary conditions, said method comprising the steps of:

• (a) saving contents of all registers of said communication control processor in an exception stack frame;
• (b) decoding said instruction to identify which register is associated with said unaligned memory access code and with which digital data is to be interfaced;
• (c) interfacing said digital data with a prescribed register of said exception stack frame, said prescribed register saving contents of said processor register identified in step (b);
• (d) restoring contents of said all registers with contents their corresponding registers in said exception stack frame;
• and
• (e) incrementing a program counter by a value that points to the next instruction following said instruction containing said unaligned memory access code.