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LDREX, STREX does not work as I expected in M4/M4F

Andy nguyen

Hi,

As I expect:

LDREX will Lock the address of VarTest. If I change vale of VarTest, STREX will return 1.

But in my test (Picture below). after all, VarTest4 = 0 although I modify VarTest before STREX. As I expected VasTest4 have to is 1.

Thanks and best regards!

I 

  • +1

    The example code, if your intent is to try the LDREX/STREX instructions, should probably be changed to declare the variables as volatile.

    Otherwise it is likely that the compiler makes optimizations that invalidate your test.