"xrl p1,#0fh ;intenstion is clear lines(p1.0,1.1& 1.2)"
Baad, should be anl p1,#0f0h. The xor will compound the problem if something is wrong.

This, - your code or changed as above - will probably cause a problem when you use memory above 64k combined with I/O

I think you have a problem with an interrupt sometimes coming in somewhere in your device access sequence, that will definitely screw your code up.

Maybe you need to disable interrupts before I/O access and reenable them afterward.

Stuff like this always require EXTREME care in interrupt handling, one idea would be to shadow p1 and save and restore at all interrupts.

Erik