features.md

@lctrl decorator

Declare a function to be called when a custom LCTRL n register is read:

@lctrl(500) Handler(pri, alt)
{
	return 42;
}

The decorator parameter must be a bare number. The function name doesn't matter. The values of pri and alt are the values of those registers when LCTRL is invoked. This function must return a value, which is set to pri.

@sctrl decorator

Declare a function to be called when a custom SCTRL n register is read:

@sctrl(500) Handler(pri, alt)
{
	printf("sctrl 500 called");
}

The decorator parameter must be a bare number. The function name doesn't matter. The values of pri and alt are the values of those registers when SCTRL is invoked.

Call Handlers

Calling the handlers is done via LCTRL and SCTRL in assembly:

#emit SCTRL            500
#emit LCTRL            500