(This question was originally posted in the Stellaris area but Dave pointed out that it really belongs here)
__ldrex and __strex intrinsics don't qualify parameter with volatile.
According to ARM, the pointer parameter should be "volatile void*".
http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0491c/CJAFAFAF.html
I have a variable which many source tasks race to change from zero to non-zero; this should use LL-SC. But only one sink task can change it when already non-zero. The sink task therefore doesn't need LL-SC, merely a volatile read and volatile write. However, the compiler won't let me mark the variable as volatile.
These intrinsics should accept a pointer to volatile, because they access the location with volatile semantics, and the volatile qualifier can be implicitly added but not removed.
volatile uint8_t active;
do {
if (__ldrexb(&active)) return;
} while (__strexb(5, &active));
Can anyone confirm that this is an error in TI's toolchain? I wanted to submit a bug report to TI, but the support form at http://www.ti.com/general/docs/contact.tsp didn't seem to have a category related to compilers.
Or is there some reason that these instructions wouldn't behave as expected with volatile variables?
