INT

INT (Interrupt) is one of the Special opcodes in the DCPU-16 specification. It triggers an interrupt from the software.

Usage

 INT arg1

If the IA register has been set to a non-zero value, INT will trigger an interrupt from software. First, interrupt queueing will be turned on. Then, first the PC and then the A registers are pushed to the stack. Finally, the PC is set to IA, and A is set to arg1.

If the IA register is zero, the interrupt will be ignored, although the instruction still takes four clock cycles.

Returning from an interrupt

The RFI instruction should be used to return from an interrupt.

Example

SET ia, myISR   ; interrupts will be handled by myISR (Interrupt Service Routine), below
SET a, 1
INT a
ADD a, 2
:end
SET pc, end
 
:myISR
SET b, 1
ADD b, a
RFI a   ; continues execution at ADD a, 2

Processing

In binary machine code, this Special opcode's five-bit representation is: 0b0 1000 (0x08)

The instruction has a takes four cycles to execute, plus any additional cycles necessary to evaluate the argument.

References

• DCPU-16 specification v1.7 (Copyright 2012 Mojang)