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Installing Shared Interrupt Handlers

An interrupt handler to be installed with RTInstallSharedIRQHandlerEx should have the following structure:

• It should be declared as an int C/C++ function with one pointer parameter.
• The handler should determine which interrupt conditions (if any) are pending for the device and handle them all. If no interrupt conditions are active, then the interrupt was probably triggered by some other device and the handler should return 0 immediately. If one or more interrupt conditions have been handled and the interrupt is level (and not edge) triggered, a value > 0 should be returned.
• The handler can communicate with other tasks using mechanisms that cannot lead to blocking task switches.

Note that the handler will be called with interrupts enabled and that the handler should not call any interrupt controller specific functions.

Example:

int IRQ = 3; 
int IOBase = 0x2F8; 

int RTKAPI IntHandler(void * P)         // high level interrupt handler 
{ 
   int IOBase = * (int*)P;              // get the device context 
   int Count = 0; 

   while (RTIn(IOBase+IIR) & 0x0C)      // receive int? 
   { 
      char Data = RTIn(IOBase+RXB);     // get the received byte 
      RTKPutCond(Buffer, &Data);        // and insert in mailbox 
      Count = 1; 
   } 
   return Count; 
} 
... 
int main(void) 
{ 
   ... 
   RTInstallSharedIRQHandlerEx(IRQ, IntHandler, &IOBase); 
   // program device to start sending interrupts here 
   ... 
   // program device to stop sending interrupts here 
   RTRemoveSharedIRQHandlerEx(IRQ, IntHandler, &IOBase); 
   ... 
 }

Interrupt Handling

Interrupt Handler for RTKSetIRQHandler