Dynamic address mapping for conflict-free vector access

摘要

Conflict-free vector access of any constant stride is made by preselecting a storage scheme for each vector based on the accessing patterns to be used with that vector. A respective storage scheme for each vector, for example, is selected to provide conflict-free access for a predetermined stride S. The respective storage scheme involves a rotation or permutation of an addressed row of corresponding memory locations in N parallel modules in main memory. The amount of rotation or permutation is a predetermined function of the predetermined stride S and the row address. The rotation is performed by modulo-N addition, or the permutation is performed by a set of exclusive-OR gates. For a system in which N is a power of 2 such that n=log.sub.2 N, the predetermined stride S is factored into an odd component and an even component that is a power of 2. The factorization is easily performed by a shift and count procedure, a shifter and counter, or a priority encoder. The amount of rotation or permutation is a predetermined function of the even component and the row address, and is preferably obtained by selecting a field of the row address in accordance with the maximum of s and n, and masking the selected field with a mask generated from the minimum of s and n.