Use ReverseBytes32 and ReverseBytes64 to speed up these functions.
The byte reversal functions are intrinsics on most platforms and
generally compile to a single instruction.
name old time/op new time/op delta
Reverse32 2.41ns ± 1% 1.94ns ± 3% -19.60% (p=0.000 n=20+19)
Reverse64 3.85ns ± 1% 2.56ns ± 1% -33.32% (p=0.000 n=17+19)
Change-Id: I160bf59a0c7bd5db94114803ec5a59fae448f096
Reviewed-on: https://go-review.googlesource.com/c/159358
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Robert Griesemer <gri@golang.org>