SPI slave ISR not raised

[aznoohwee]

I found that IRQ is not raised when simulating firmware operating as a SPI slave.

PR is WIP to see if there is anything else that needs to be done but here is a quick fix.

static avr_cycle_count_t avr_spi_raise(struct avr_t * avr, avr_cycle_count_t when, void * param)
{
avr_spi_t * p = (avr_spi_t *)param;

if (avr_regbit_get(avr, p->spe)) {
	// in master mode, any byte is sent as it comes..
	if (avr_regbit_get(avr, p->mstr)) {
		avr_raise_interrupt(avr, &p->spi);
		avr_raise_irq(p->io.irq + SPI_IRQ_OUTPUT, avr->data[p->r_spdr]);
	}
    // in slave mode, bytes are sent but no interrupt is raised
    // TODO check for state of SS line??
    else {
		avr_raise_irq(p->io.irq + SPI_IRQ_OUTPUT, avr->data[p->r_spdr]);
    }
}
return 0;

}

[aznoohwee]

Related to #222

[buserror]

Good catch -- to be fair I've haven't had to use spi slave in a long time, so that probably had been left as 'an exercise to the reader' ;-)
Please PR, even if it's not all polished, as long as you are happy it works...

[aznoohwee]

Closing this issue in favor of #300