On Monday, 27 June 2016 at 16:22:56 UTC, Jay Norwood wrote:
This strlen2 doesn't require special alignment or casting of
char pointer types to some larger type. That keeps the strlen2
implementation fairly simple.
Yes, and the idea of speeding up strings by padding out with
zeros is not new. ;-) I recall suggesting it back in 1999 when
discussing the benefits of having a big endian cpu when sorting
strings. If it is big endian you can compare ascii as 32/64 bit
integers, so if you align the string and pad out with zeros then
you can speed up strcmp() by a significant factor. Oh, here it is:
http://disinterest.org/resource/MUD-Dev/1999q1/009759.html
Of course, this is all moot now, little endian + simd has made
such tricks redundant. Simd probably makes your strlen2 redundant
too. The bottle neck tends to be memory access/prefetching for
simple algorithms.
