I’d like to copy a lot of data from volatile memory.

memcpy() can read several times, different data sizes and all, which doesn’t matter in my case since the memory is safe once I call memcpy().

The only problem could be memcpy() doesn’t copy the n bytes I instructed it to copy due to optimization.

Is it possible, or does memcpy() (gcc) guarantee n bytes are copied (again, no matter how many reads and their sizes)?

I’d like to avoid writing this myself since memcpy()‘s gcc implementation must be faster (n being a constant), and src and dst are both RAM, not IO.