Fast Bit Compression and Expansion with Parallel Extract and Parallel Deposit Instructions

Current microprocessor instruction set architectures are word oriented, with some subword support. Many important applications, however, can realize substantial performance benefits from bitoriented instructions. We propose the parallel extract (pex) and parallel deposit (pdep) instructions to accelerate compressing and expanding selections of bits. We show that these instructions can be implemented by the fast inverse butterfly and butterfly network circuits. We evaluate latency and area costs of alternative functional units for implementing subsets of advanced bit manipulation instructions. We show applications exhibiting significant speedup, 3.41¿ on average over a basic RISC architecture, and 2.48¿ on average over an instruction set architecture (ISA) that supports extract and deposit instructions.