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    <blockquote> <p>The cortex M3 processor startup file allows you to specify the amount of RAM dedicated to the stack and the heap.</p> </blockquote> <p>That is not a feature of the Cortex-M3, but rather the start-up code provided by your development toolchain. It is the way the Keil ARM-MDK default start-up files for M3 work. It is slightly unusual; more commonly you would specify a stack size, and any remaining memory after stack and static memory allocation by the linker becomes the heap; this is arguably better since you do not end up with a pool of unusable memory. You could modify that and use an alternative scheme, but you'd need to know what you are doing.</p> <p>If you <em>are</em> using Keil ARM-MDK, the linker options --info=stack and --callgraph add information to the map file that aids stack requirement analysis. These and other techniques are described <a href="http://www.keil.com/support/man/docs/armlink/armlink_pge1362075422709.htm" rel="nofollow noreferrer">here</a>. </p> <p>If you are using an RTOS or multi-tasking kernel, each task will have its own stack. The OS may provide stack analysis tools, Keil's RTX kernel viewer shows current stack usage but not peak stack usage (so is mostly useless, and it only works correctly for tasks with default stack lengths).</p> <p>If you have to implement stack checking tools yourself, the normal method is to fill the stack with a known value, and starting from the high address, inspect the value until you find the first value that is not the fill byte, this will give the likley high tide mark of the stack. You can implement code to do this, or you can manually fill the memory from the debugger, and then monitor stack usage in a debugger memory window.</p> <p>Heap requirement will depend on the run-time behaviour of your code; you'll have to analyse that yourself however in ARM/Keil Realview, the MemManage Exception handler will be called when C++'s <code>new</code> throws an exception; I am not sure if <code>malloc()</code> does that or simply returns NULL. You can place a breakpoint in the exception handler or modify the handler to emit an error message to detect heap exhaustion during testing. There is also a a <a href="http://www.keil.com/support/man/docs/armlib/armlib_chr1359122851244.htm" rel="nofollow noreferrer">__heapstats()</a> function that can be used to output heap information. It has a somewhat cumbersome interface, I wrapped it thus:</p> <pre><code>void heapinfo() { typedef int (*__heapprt)(void *, char const *, ...); __heapstats( (__heapprt)std::fprintf, stdout ) ; } </code></pre>
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