It searches are different for the <=88 case and the >88 case.
So if one person calls at 88, he wins.
If more than one calls at 88 then it searches up. If 0 calls at 88 then it searches down.
Here's how the down-search works: It simply looks for the highest unique call between 1 and 87
Here's how the up-search works: It goes one at a time up starting at 89 to see if there's a value with 0 or 1 calls. If it finds one with 0 calls then it deadlocks and the pot rolls over. If it finds one with 1 then that person wins.