A decompression core for powerPC

  • Authors:
  • T. M. Kemp;R. K. Montoye;J. D. Harper;J. D. Palmer;D. J. Auerbach

  • Affiliations:
  • IBM Microelectronics Division, Almaden Research Center, 650 Harry Road, San Jose, California;IBM Research Divsion, Thomas J. Watson Research Center, P. O. Box 218, Yorktown Heights, New York;IBM Microelectronics Division, 11400 Burnet Road, Austin, Texas;IBM Research Divsion, Almaden Research Center, 650 Harry Road, San Jose, California;IBM Research Divsion, Almaden Research Center, 650 Harry Road, San Jose, California

  • Venue:
  • IBM Journal of Research and Development
  • Year:
  • 1998

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Abstract

Code size efficiency is a critical parameter in the design of computer systems for embedded applications. This paper describes a method for improving code size efficiency involving the use of compression techniques to reduce the size of the stored code, and on-the-fly hardware decompression at full processor speed for execution. A simple frequency-based encoding scheme for PowerPC® code achieves a typical code size reduction to 60% of the original size. A corresponding decompression core has been implemented for an embedded microprocessor, such as the PowerPC 401TM. The compression/decompression scheme operates in a manner transparent to the processor and requires no changes to such tools as compilers, linkers, and loaders.