erik;
in read modify write the destination is always the port SFR.so i can not get its value.if i use mov a,p2 etc. i get port pin.i can only modify port latch not read it.as you wrote by maintaining a shadow that tracks every change in p2 it is possible.but i wanted that job to be done by a supervisory program.in case of shadow one is assuming that running code is not preempted by other code which also uses p2.i tried preemption successfully for acc,psw,b etc.since one can not read P2 directly it still IS a problem.i dont think its possible.
regards
pranav
p.s.sorry for incoherent writing