Run time Data and Code memory size estimate

Question

I am working on a project, C programing language, to develop an application, that can be ported on to a number of different microcontroller platforms, such as ARM\Freescale\PIC microcontroller. I am developing this application on Linux now and then I will have to port it to the above said platforms.

I would like to know, are there any tools (open source preferably), using which I can determine the "code" and the data memory footprint\size, before porting it to the new platform.

I have been searching on "Google" for it and have not found anything so far, not even for Linux as well.

any help from you will greatly help me.

-Vikas

Answer 1

Nothing can tell you how much memory your application will need. You'll have to make some assumptions about how it will be used and try your application under different scenarios.

As you're testing, you can monitor the memory usage stats in the /proc file system or use the ps command to do the same.

Answer 2

Your compiler can/will generate a map file. The map file will, generally speaking, have code and data size (or location ranges). There may be differences between different compilers for the different targets. And as pointed out in other posts here, your dependencies on supplied libraries will also impact overall memory usage.

Answer 3

For a small program, much of the size is determined by the libraries/DLL your program depends on. Since you refer to ARM/Freescale/Pic I assume you're dealing with compact, embedded applications where data size is measured in bytes rather than MBytes.

For your own code, size differences will determined by:

• word size (i.e. 32bit programs tend to be a bit larger /more data than 8 bit)
• architecture (i.e. Intel code versus ARM, freescale, PIC)

In your case, I expect that PIC is the most critical part (for RAM/ROM constraints). So propably monitoring the PIC compile size during PC development is sufficient. The linker output will contain info on TEXT/DATA/BSS size, which you can monitor.

I generally work on embedded systems. In my work much of the data size is known at design time (i.e. number of buffers * buffer size). For code size, I have rules of thumb on different architectures which help me to do a sanity check at design time. For instance, I define a suite of some exising-code libraries, for which I know performance and size numbers for each architecture. This way I know what kind of ratio I can expect at design time. If the PC program has 1 MBytes of data, it won't fit in an 8-bit PIC.....

Answer 4

The size of your text/code segment will depend on optimization level and back-end. GCC can be configured to generate that information for you.

Run-time is a little more difficult as Jeremy said. Besides his suggestion, you also might want to try gcov and/or gprof in order to analyse your program in the context of your most common use scenarios. This kind of instrumentation is focussed on complexity rather than size but at least you'll know better where to focus your memory analysis.