If I understand your question,it looks as though your code is in the count down loop and cannot be updated with a status change until the loop is complete.I also don't understand your use of call as the manual suggest usage for accessing assembly code.With the amount of time delays your code requires,I would suggest using the timer interrupt and accumulate ticks.This will let your program run faster,plus if a status change occurs your code can respond properly.There are demo's of the timer interrupt either with PBP or on Microengineerings web site.