Standardized Functional Verification- P17:Every manager who brings a design to tape-out or who purchases IP must eventually face these questions. The ability to answer these questions based on quantitative analysis is both vital and yet elusive. In spite of the enormous technical advances made in IC development and verification software, the answers to these questions are still based largely on guesswork and hand waving. | Standard Measures of Function Space Coverage 145 VTG coverage arc VTG coverage point composite state machine arc transversability composite state machine state reachability code coverage path toggle trigger code coverage condition code coverage branch code coverage line Fig. . Relative strength of measures of coverage coverage fall between these two extremes as shown in Fig. . The relative positions of the various measures along the vertical axis of increasing strength are only approximate but serve to indicate how strongly each should be considered when assessing risk at tape-out the topic of the next chapter. Standard Measures of Function Space Coverage In our discussion on standard measures and later on standard views it s necessary to keep in mind that the measures described in this section are only the beginning of the evolution of widely-adopted standards with regard to measuring functional coverage for an IC or other digital system. The measures described in the remainder of this section might better be regarded as candidates for inclusion in a standard. 146 Chapter 6 - Analyzing Results Useful and productive candidates will be embraced by the verification community and eventually by standards-making bodies. Those that are either not useful or not productive will fall by the wayside. Accumulation of empirical data within the industry will lead to the discovery of other more useful and productive measures that will add to the standard or replace some existing measures. Regression results are retained for the purpose of generating standard measures by way of data-mining. Ideally complete execution histories of all tests would be saved for later analysis. However this is not always practical due to the considerable disk space consumed by the simulation results. But considering the economics of cheap disk storage vs. expensive mask sets this storage can be a very worthwhile investment. The standard measures are the basic measures for how .
