:
s/=\(9\)\{5\}\?\(9*\)|/|\1=\2\2/
t
s/=/=012345678/g
s/=\(\w\)*\w\{8\}/\1/g
/644/d
s/|\+0*//p
g
s/^$/|||||||||||||||9/
s/\(\(|9*\)\{7\}.*\)|\(9*\)/\2\3\1/
s/99//
h
s/^/=====/
b
Note that non-ascii characters in the above source code will be escaped (such as \x9f).