[avr-gcc-list] Preemptable Interrupts

[Steve Joiner]

Hi folks,

I'm hoping someone can help me with a little problem that's got me
stumped.

I'm trying to figure out how to make the SIG_UART_DATA and SIG_UART_RECV
signals preemptable.  I've got another interrupt that I want interrupt
the UART interrupts if it comes along.  I've also got other lower
priority interrupts that I don't want interrupting the UART interrupts.

I was originally trying to do something like this:

SIGNAL(SIG_UART_DATA)
{
    cbi(TIMSK, TOIE2); /* disable lower priority interrupt */
    cbi(UCSRB, RXCIE); /* disable UART transmit interrupt */
    /* don't disable higher priority interrupt */
    sei(); /* turn interrupts back on */

    /* do stuff here, (minimal amount of code, of course) */

    cli();
    sbi(UCSRB, RXCIE); 
    sbi(TIMSK, TOIE2);
}

The problem is that if a byte is received during the ISR, but RXCIE is
cleared, the interrupt is lost.  Does anyone know of a way to accomplish
what I'm trying to do here?

Thanks,
Steve Joiner