How to read pin value On LPC2468 ?
Read datasheet.
it is typically done via the IO Port Data register. and can bed one with the Pin register as well.
or you can define a structure with bit variables to the same address as your Port register.
that's assuming that you are reading digital input.
reading analog input is a different story.
What is the IO Port Data Register?
To my knowledge, the LPC2468 only have a pin register - either called IOxPIN or FIOxPIN with the IOxPIN alternative only being available for P0 and P1.