I have started learning ARM assembler and I would like to write some project (not so big) to get proficiency in it. My problem is I am not sure what to write. I would like the project to be practical, not only educational, so other people could use it. I've been thinking about developing really fast integer FFT for ARM, but I am not sure whether it is good idea. My doubts are:

- does something like this already exist? If it does, is it free? I emphasize that I mean about integer (fixed-arithmetic) FFT here.
- how much efficiency, if any, can I get writing it entirely in assembler? Can I be better than compiler?

If you think that FFT is not good choice, do you have some other ideas of projects that would be suitable?
Maybe you know about some projects already started where I could train my assembler programming skills participating with?

My experiences with ARM processor compilers are very good, so chances are that compiled C++ code won't be any slower than the one written in assembler.

If your objective is simply to learn assembler coding, then don't worry if your code can't keep up with a compiled version. If you want a project that is practical in nature, then focus on things that are not normally done with compiled languages, such as startup code, some bootloader code, etc. For examples of these, look in the Linux kernel sources.
You probably can be more efficient than a compiler, but your initial versions probably will not be. Compilers are pretty smart these days.
--- rod.