Nonlinear Compression Block Codes Search Strategy

This paper deals with extending linear compression codes by nonlinear check bits that improve the usability of decompressed patterns for testing circuits with more inputs. The earlier works used a purely random or partially random search of the nonlinear check-bits truth tables to construct the first nonlinear structures. Here, we derive deterministic rules that characterize the relationship among the nonlinear code check bits. The efficiency of the rules is demonstrated on different codes with the number of specified bits equal to three. The code parameters obtained after applying the rules overperform the parameters of the linear codes. Keeping the restrictions makes the search for the check bit truth tables faster and more efficient than can be got by a simple random search. The reached nonlinear block code (136,5,3) is the most efficient code among other loose compression codes.