On Tue, Feb 9, 2021 at 4:22 PM Heikki Linnakangas <hlinn...@iki.fi> wrote: > > On 09/02/2021 22:08, John Naylor wrote: > > Maybe there's a smarter way to check for zeros in C. Or maybe be more > > careful about cache -- running memchr() on the whole input first might > > not be the best thing to do. > > The usual trick is the haszero() macro here: > https://graphics.stanford.edu/~seander/bithacks.html#ZeroInWord. That's > how memchr() is typically implemented, too.
Thanks for that. Checking with that macro each loop iteration gives a small boost: v1, but using memcpy() mixed | ascii -------+------- 601 | 129 with haszero() mixed | ascii -------+------- 583 | 105 remove zero-byte check: mixed | ascii -------+------- 588 | 93 -- John Naylor EDB: http://www.enterprisedb.com
