Complexity metrics for avionics software

Describes extensions to the Halstead Software Science measures for avionics software written in Ada. The Halstead measures are based only on the syntax of the program text (operators and operands) without considering the semantics of the applications. Multitasking real-time software, widely used in avionics control, is generally more difficult to design, implement, test, and comprehend due to the interaction of concurrent processes and real-time constraints. Because Ada was designed to support the development of real-time embedded systems, it has introduced concepts such as tasking, exception handling, and intertask communication. The metrics extensions make use of these new Ada language constructs to capture the characteristics of avionics software and measure its complexity. A metrics study conducted on production-grade real-time software indicated that the extended Halstead metric has a stronger correlation to bug reports found during testing