10.2.1. Adding Interrupt Generation Functions to the Or1ksim Library

The additional function allows the external SystemC model to call into the Or1ksim ISS to request an interrupt. The ISS requires that interrupts are not taken mid-instruction (for example while a peripheral memory access upcall is in progress), so a flag is set internally, allowing the ISS to trigger the interrupt at the start of the next instruction.

The standard version of Or1ksim uses edge triggered interrupts, and they are used in this example. However Or1ksim can support level triggered interrupts. For this additional interface functions are provided, although they are not used in this example.

```
void or1ksim_interrupt( int  i );
		
```
or1ksim_interrupt requests the the interrupt given by its argument be taken at the start of the next instruction cycle. This is edge-triggered interrupt functionality, and there is no need to clear the interrupt.
```
void or1ksim_interrupt_set( int  i );
		
```
or1ksim_interrupt_set asserts the interrupt given by its argument for consideration by Or1ksim at the start of the next instruction cycle. This is for level triggered interrupt handling, and must be explicitly cleared when the interrupt handling is complete.
```
void or1ksim_interrupt_clear( int  i );
		
```
or1ksim_interrupt_clear deasserts the interrupt given by its argument for consideration by Or1ksim at the start of the next instruction cycle. This is to clear an interrupt previously asserted with void or1ksim_interrupt_set when using level triggered interrupt handling. or1ksim_interrupt requests the interrupt given by its argument be taken at the start of the next instruction cycle.

These functions are a standard part of the Or1ksim 0.3.0 and Or1ksim 0.4.0 libraries.