Faster way to zero memory than with memset?

Question

I learned that memset(ptr, 0, nbytes) is really fast, but is there a faster way (at least on x86)?

I assume that memset uses mov, however w

Answer 1

memset is generally designed to be very very fast general-purpose setting/zeroing code. It handles all cases with different sizes and alignments, which affect the kinds of instructions you can use to do your work. Depending on what system you're on (and what vendor your stdlib comes from), the underlying implementation might be in assembler specific to that architecture to take advantage of whatever its native properties are. It might also have internal special cases to handle the case of zeroing (versus setting some other value).

That said, if you have very specific, very performance critical memory zeroing to do, it's certainly possible that you could beat a specific memset implementation by doing it yourself. memset and its friends in the standard library are always fun targets for one-upmanship programming. :)