int irq_free(int irq);
Releases a hardware interrupt that was previously intercepted with irq_request, once again allowing the normal DOS handler to service the interrupt. If the interrupt was disabled before irq_request was called, then irq_free will cause it to be disabled again.
- The hardware IRQ number to release, 0-15.
Returns 0 if successful, or -1 on error, in which case errno indicates the error.