VHDL design optimization for two-dimensional filters
Nelson Luiz Passos, Jian Song, Robert P. Light, Ranette Halverson, Richard P. Simpson · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1999
Multi-dimensional applications, such as image processing and seismic analysis, usually require the high computer performance obtained from the implementation of Application Specific Integrated Circuits (ASICs). The critical sections of such applications consist of nested loops with the possibility of embedded conditional branch instructions. Current commercial systems use branch predication techniques, which can also be applied in the design of ASIC systems. Those techniques utilize predicate registers to control the validity of computed results. The optimized design and allocation of such registers becomes then a significant factor in the performance of the system. By using branch prediction to transform control dependencies in data dependencies, the application of a multi-dimensional retiming to an MDFG permit the iterations of the original loop body to be naturally overlapped, making the existent parallelism explicit. Based on the retiming information, predicate registers are designed as shift registers that allow the correct execution of the filter function.