A Dictionary Encoding Method for Test Data

Abstract

The invention relates to a test data dictionary coding method which includes the following steps of: generating dictionary entries; aiming at each dictionary entry, performing reverse compatibility analysis, and determining scanning sections reverse compatible with the dictionary entries; and coding each scanning section according to a set rule. The method of generating the dictionary entries also includes the steps that: an undirected graph G is established by taking each scanning section as a vertex, if any two scanning sections are compatible, an edge is formed between the vertexes corresponding to the scanning sections; m maximum complete subgraphes are obtained through a heuristic algorithm, m being the number of default dictionary entries; and the dictionary entry corresponding to each maximum complete subgraph is generated. When the reverse compatibility analysis is performed on the dictionary entries, the heuristic algorithm is introduced. The maximum complete subgraph of the graph formed by the scanning sections reverse compatible with the dictionary entries is found, the coding rule is combined, and a compression ratio of the test data is improved.

Description

technical field [0001] The invention relates to the technical field of digital processing, in particular to a dictionary encoding method for test data. Background technique [0002] With the increase of integrated circuit design scale, the amount of test data increases exponentially, which leads to severe problems such as insufficient storage space, limited IO bandwidth and long test time for traditional external automatic test equipment (ATE). Higher and higher. One of the effective ways to solve the above problems when testing data compression, through compression can reduce data transmission time and reduce the requirements for ATE storage capacity. [0003] Test data usually contains a large number of don't care bits (X-bit), these don't care bits can be assigned as 0 or 1 arbitrarily without affecting the fault coverage. Therefore, using an appropriate encoding algorithm combined with a corresponding irrelevant bit filling strategy can achieve data compression and imp...

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Problems solved by technology

[0006] Liu Jie et al. considered that the scanned slice to be encoded is compatible with dictionary entries, reverse compatibility, shift compatibility and shift reverse compatibility, etc., but when performing reverse compatibility and shift compatibility, etc. When judging the situation, when the dictionary entry utilizes reverse compatibility (or shift compatibility) to encode multiple scan slices, how to realize the problem of encoding the most scan slices to achieve high compression ratio; and due to compatibility There are many possibilities for the existence of sex, resulting in many prefixes of the encoded codeword, which will have a certain impact on the compression rate

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