Bitmask-Based Code Compression for Embedded Systems

Abstract

Embedded systems are constrained by the available memory. Code-compression techniques address this issue by reducing the code size of application programs. It is a major challenge to develop an efficient code-compression technique that can generate substantial reduction in code size without affecting the overall system performance. We present a novel code-compression technique using bitmasks, which significantly improves the compression efficiency without introducing any decompression penalty. This paper makes three important contributions. 1) It develops an efficient bitmask-selection technique that can create a large set of matching patterns. 2) It develops an efficient dictionary-selection technique based on bitmasks. 3) It proposes a dictionary-based code-compression algorithm using the bitmask- and dictionary-selection techniques that can significantly reduce the memory requirement. To demonstrate the usefulness of our approach, we have performed code compression using applications from various domains and compiled for a wide variety of architectures. Our approach outperforms the existing dictionary-based techniques by an average of 20%, giving a compression ratio of 55%-65%.