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Dynamic Memory Allocation in Embedded Apps?
shootTheMessenger asks: "My company is porting our C++ Windows app to C in an embedded device and the question of whether to use dynamic memory allocation continues to come up. So far I have resisted malloc/free use but it gets tedious having the same argument with the next set of managers to take an interest in the project. Is there a definitive answer on the subject, especially one to counter the 'we have plenty of RAM - 16MB - so why not use dynamic allocation' argument? A quick google search finds that some sites frown on allocations within embedded applications, while others say it is OK in some contexts and yet others hack around it with pseudo-static allocations. How do you feel about this particular subject?"
Memory fragmentation is murder on embedded devices. Do your best to avoid dynamic allocation unless static pools results in huge memory waste because your app is highly modal. Where dynamic allocation is a must, set up multiple heaps and find points where you can add code to free everything on that heap when switching modes to guarantee a fresh slate. If you have tons of small allocations, also consider setting up special heaps that handle fixed-size allocations. Having these parcelled off into their own area can go a long way toward fragmenting the space where the bigger allocations reside and you might find it's easier to find points where you can wipe heaps without the small allocations in the way.