Nirenjan’s Space

WARNING: This is a technical post…

I don’t know how many of you would have heard of the (in?)famous QAC software program that analyzes your C code for quality. I had the privilege of running it a couple of days ago on a few of the driver modules and among the errors thrown up were a few gems.

1. C++ Style comments not allowed: OK, I’ll accept that. Some people say that it is preferable to use the standard block comments (/* … */) instead of the single line comments (// …) and I’m not about to counter that.
2. Conversion between a pointer and integer is implementation defined: This particular error came up more than a few hundred times. The hardware I use contains configuration registers that are memory mapped and so I have to use a pointer to address them. QAC starts complaining…
3. Conditions to be made explicit: In C (or C++), any expression evaluating to a non-zero quantity is treated as true in a condition. Similiarly, a zero value is treated as false. We had made use of this feature more than once, and once again, QAC began to complain…
4. Every condition should have a block: (OK, this was not the actual text.) What this actually meant was that if I had a single statement to be executed if a particular condition was valid, I still had to enclose it with the curly braces. I’m actually for this kind of coding practice as it helps to trap quite a number of bugs. Where this really threw rocks at me was on a line like this: while (<condition>);. We had a few lines where the software waits for a particular condition to happen (like a register bit getting set or reset). What QAC expected was more of the following:
   
while (<condition>)
{
    ;
}

This actually sounds crazy to me. I believe that there is no point in putting a null statement within curly braces while waiting. I also think that this kind of a statement would actually hinder the readability.

Now don’t get me wrong. I think QAC is a great tool for quality checks, but then again, some of those warnings can just be ignored…

This entry was posted on Saturday, June 4th, 2005 at 11:58 pm and is filed under Programming. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.