Speed enhancement of digital signal processing software via microprogramming a general purpose minicomputer

Execution time of digital signal processing (DSP) software can be substantially reduced using automatically generated code which incorporates precomputed, data-independent control and data access parameters. In this paper, further speed enhancement of such software via microprogramming of computation kernels is discussed and demonstrated. It is shown that, in addition to elimination or reduction of instruction fetch and decode overhead, and reduction of data access time via use of high-speed scratchpad registers, microprogramming may permit fundamental operations to be recoded to yield substantially reduced execution times. An example is given whereby Booth's multiplication algorithm is implemented in microcode to yield a fixed-point multiply/add time several times faster than an implementation using the machine-level multiply/add instructions. Moreover, the systematic nature of the computational microcode allows it to be generated by programs using the technique described previously. Finally, program execution times approaching an order of magnitude less than that of conventional assembler language implementations are shown to be feasible by incorporation of all techniques discussed.