Unrolling loops with indeterminate loop counts in system level pipelines

Abstract

This paper describes the unrolling of loops with indeterminate loop counts in system level pipelines. Two methods are discussed in this paper. The first method is the varied latency method, where the input is blocked until the pipeline is clear. This variation in the input arrival time gives rise to the name. In this method the output will be in the same order as the input. The second method, called the fixed latency method, allows for the input arrival time to remain unchanged. The loops with loop count in excess of the number of unrolled loops will have to be stored, until a suitable gap in the system becomes available. Analysis of the both methods is given, which shows that the fixed latency method is significantly faster but needs reordering of tasks and memory to store tasks.