CONVERTING CODE FROM THE TMS320C5X DSP TO THE TMS320C2XX DSP

With the introduction of the TMS320C2xx (C2xx) family of low-cost digital signal processors (DSPs), many customers are discovering that they can utilize this DSP family for designs that previously required the processing power of a TMS320C5x (C5x) DSP. Although some code has been written for the C2xx, reuse of the large repository of C5x application code can dramatically speed up designs using the C2xx. Since the architecture and instruction set of the C2xx is similar to the C5x, porting of code from the C5x to the C2xx is fairly straightforward.

The C2xx instruction set is fully capable of implementing the functionality of the omitted and changed C5x instructions, although usually at the cost of a minor increase in program memory and cycle counts. Since most code replacement involves the use of alternate resources, efficient porting of C5x code requires careful review of the surrounding code to prevent unneeded context save and restore. Sometimes restructuring the code is the only way to prevent large inefficiencies. For these reasons, no automatic conversion utilities exist.

This paper describes the architectural differences in the C5x and C2xx CPU cores and provides example replacement code for all omitted and changed C5x instructions. The implications of each replacement are also described, including the cost in cycles and memory usage. Because of the need for system-level consideration, differences in internal memory and peripherals and their configuration are not covered.

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