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In the context of software evolution, many activities are involved and are very useful, like being able to evaluate the design quality of an evolving system, both to locate the parts that need particular refactoring or reengineering efforts, and to evaluate parts that are well designed. This paper aims to give support hints for the evaluation of the code and design quality of a system and in particular we suggest to use metrics computation and antipatterns detection together. We propose metrics computation based on particular kinds of micro-structures and the detection of structural and object-oriented antipatterns with the aim of identifying areas of design improvements. We can evaluate the quality of a system according to different issues, for example by understanding its global complexity, analyzing the cohesion and coupling of system modules and locating the most critical and complex components that need particular refactoring or maintenance.

We present a methodology for on-chip characterization of the pin-to-pin propagation delay of single standard cells. A periodic waveform is provided to an input pin of the standard cell under characterization, while keeping all other inputs at non-controlling logic values. Simultaneous random sampling is then applied to input and output periodic waveforms, and propagation delay measures are obtained from the joint signal probabilities of the samples. The proposed technique is suitable for on-chip implementation because it is simple and it doesn't require timing-accurate control signals. On the other hand, on-chip measurements can be applied to a large number of cells working in different operating conditions, providing valuable information for characterizing and validating timing models. A test chip has been realized in a 0.18 /spl mu/m embedded NVM CMOS technology, and used to monitor the sub-nanosecond timing behavior of a standard cell library during process development.