count 64 bits at a time instead of 8 (#12159)
count 64 bits at a time instead of 8 (#12159)

* count 64 bits at a time

* spacing

* only do 64bts on x86

* add amd64

* use while

dom96/Nim,dom96/Nim,dom96/Nim,dom96/Nim,dom96/Nim,dom96/Nim,dom96/Nim