hello:
    I am trying to make the NIC  dm9000 work on my board AT91sam9263.The interrupt signal of dm9000 is connected to the 
PD4,and I have to write a callout for the  gpio.
   I am not very sure the following issues,can anyone give me some help?
      1   where could I put the callout_*.S?/ startup/boards/at91sam9263     or /startup/lib?just put in it ty
       2   how the callout code worked?can you tell me more details about the callout,and callout_interrupt ? I had read
 the help doc in the IDE,but it seems to be unclear.
       3   how to write a cascade interrupt callout and how to and it into the startup code?