Extended frequency-directed run-length code with improved application to system-on-a-chip test data compression

One of the major challenges in testing a system-on-a-chip (SOC) is dealing with the large test data size. To reduce the volume of test data, several test data compression techniques have been proposed. The frequency-directed run-length (FDR) code is a variable-to-variable run length code based on encoding runs of 0´s. In this work, we demonstrate that higher test data compression can be achieved based on encoding both runs of 0´s and 1´s. We propose an extension to the FDR code and demonstrate by experimental results its effectiveness in achieving higher compression ratio.