For the first time, after a long code reading, i finally can modify something  and see the happy result. The idea is not come up recently, using the MV to  predict search range, however, being not familiar with the JM code block my  way.  Although there are many things to do, such as how to identify min value for  search range, and how to reasonably deduce a formula, it's the first  breakthrough.  the road is still long...
Sail on this course and take it when it comes.