Software verification techniques such as pattern-based static code analysis, runtime memory monitoring, unit testing, and flow analysis are all valuable techniques for finding bugs in embedded C software. On its own, each technique can help you find specific types of errors. However, if you restrict yourself to applying just one or some of these techniques in isolation, you risk having bugs that slip through the cracks.
A safer, more effective strategy is to use all of these complementary techniques in concert. This establishes a bulletproof framework that helps you find bugs which are likely to evade specific techniques. It also creates an environment that helps you find functional problems, which can be the most critical and difficult to detect.
This paper will explain how automated techniques such as pattern-based static code analysis, runtime memory monitoring, unit testing, and flow analysis can be used together to find bugs in an embedded C application. These techniques will be demonstrated using Parasoft C++test, an integrated solution for automating a broad range of best practices proven to improve software development team productivity and software quality.
As you read this paper — and whenever you think about finding bugs — it's important to keep sight of the big picture. Automatically detecting bugs such as memory corruption and deadlocks is undoubtedly a vital activity for any development team. However, the most deadly bugs are functional errors, which often cannot be found automatically. We'll briefly discuss techniques for finding these bugs at the conclusion of this paper.
Introducing the scenario
To provide a concrete example, we will introduce and demonstrate the recommended bug-finding strategies in the context of a scenario that we recently encountered: a simple sensor application that runs on an ARM board.
Assume that so far, we have created an application, however, when we uploaded it to the board and tried to run it, we did not see an expected output on the LCD screen.
It's not working, but we're not sure why. We can try to debug it, but debugging on the target board is time-consuming and tedious. We would need to manually analyze the debugger results and try to determine the real problems on our own. Or, we might apply certain tools or techniques proven to pinpoint errors automatically.
At this point, we can start count on good luck as we try to debug the application with the debugger. Or, we can try to apply an automated testing strategy in order to peel errors out of the code. If it's still not working after we try the automated techniques, we can then go to the debugger as a last resort.