LZW-Based Code Compression for VLIW Embedded Systems

  • Authors:
  • Chang Hong Lin;Yuan Xie;Wayne Wolf

  • Affiliations:
  • -;-;-

  • Venue:
  • Proceedings of the conference on Design, automation and test in Europe - Volume 3
  • Year:
  • 2004

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Abstract

We propose a new variable-sized-block method for VLIW code compression. Code compression traditionally works on fixed-sized blocks and its ef.ciency is limited by the smallblock size. Branch blocks -- instructions between two consecutive possible branch targets -- provide larger blocks for code compression. We propose LZW-based algorithms to compress branch blocks. Our approach is fully adaptive and generates coding table on-the-fly during compression and decompression. When encountering a branch target,the coding table is cleared to ensure correctness. Decompression requires only a simple lookup and update when necessary. Our method provides 8 bytes peak decompression bandwidth and 1.82 bytes in average. Compared to Huffman's 1 byte and V2F's 13-bit peak performance, our methods have higher decoding bandwidth and comparable compression ratio. Parallel decompression could also be applied to our methods, which is more suitable for VLIW architecture.