MISRA C Enforcement in the Safer C Toolset

The Safer C toolset goes to considerable effort to enforce the well-known MISRA C standard. The MISRA C standard was developed by a consortium of car manufacturers with the intention of introducing the notion of safer language subsets for programmable control systems in the auto industry.

It has been very successful and is now used in other industries also in which safety plays a part.

Several things must be born in mind when considering standards conformance:

• Very few standards can be fully enforced automatically. There is nearly always an element of subjectivity in even the best of standards. In some standards, it is far more than element with the average automatic enforceability being only around 30-40%, (Hatton (1995)). Such standards are characterised by somewhat vague rules such as "comments shall be meaningful". The MISRA C standard enjoys much higher levels of enforceability because the rules are based on safer subsets and are in the majority clearly written. The diagram below shows the theoretical enforceability of the MISRA C standard.

• The second thing to consider is how well particular tools enforce that part of the standard which is enforceable. The following diagram illustrates the degree to which the Safer C toolset can enforce the MISRA C standard. As can be seen, the required rules which can be enforced are almost 100% enforced.

For more about MISRA, visit http://www.misra.org.uk/