These values are processed using four sub stages in {TAIL ~ the MD5 stage} using {HEAD ~ a number} of adders along with fixed nonlinear function processing units and fixed 32 bit shift units 
These values are processed using four sub stages in { TAIL ~ the MD5 stage } using { HEAD ~ a number } of adders along with fixed nonlinear function processing units and fixed 32 bit shift units
OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH