C++ usage in embedded systems

Question

What features of C++ should be avoided in embedded systems?

Please classify the answer by reason such as:

• memory usage
• code size
• speed<

Answer 1

Having used both the GCC ARM compiler and the ARM's own SDT I'd have the following comments:

• The ARM SDT produces tighter, faster code but is very expensive (>Eur5k per seat!). At my previous job we used this compiler and it was ok.

• The GCC ARM tools works very well though and it's what I use on my own projects (GBA/DS).

• Use 'thumb' mode as this reduces code size significantly. On 16 bit bus variants of the ARM (such as the GBA) there is also a speed advantage.

• 64k is seriously small for C++ development. I'd use C & Assembler in that environment.

On such a small platform you'll have to be careful of stack usage. Avoid recursion, large automatic (local) data structures etc. Heap usage will also be an issue (new, malloc etc). C will give you more control of these issues.