Working of __asm__ __volatile__ (“” : : : “memory”)

Question

What basically __asm__ __volatile__ () does and what is significance of \"memory\" for ARM architecture?

Answer 1

The meaning is explained here:

http://en.wikipedia.org/wiki/Memory_ordering

Basically it implies that the assembly code will be executed where you expect it. It tells the compiler to not reorder instructions around it. That is what is coded before this piece of code will be executed before and what is coded after will be executed after.