Alternative Algorithms for Bit-Parallel String Matching

Abstract

We consider bit-parallel algorithms of Boyer-Moore type for exact string matching. We introduce a two-way modification of the BNDM algorithm. If the text character aligned with the end of the pattern is a mismatch, we continue by examining text characters after the alignment. Besides this two-way variation, we present a simplified version of BNDM without prefix search and an algorithm scheme for long patterns. We also study a different bit-parallel algorithm, which keeps the history of examined characters in a bit-vector and where shifting is based on this bit-vector. We report experiments where we compared the new algorithms with existing ones. The simplified BNDM is the most promising of the new algorithms in practice.