[Qemu-devel] Re: [PATCH 2/2] virtio-console: Add interface for generic guest-host communication

[Amit Shah]

On (Thu) Sep 03 2009 [17:20:44], Juan Quintela wrote:
> Amit Shah <address@hidden> wrote:
> 
> Hi
> 
> >> > > +static void virtio_console_set_port_active(uint32_t idx)
> >> > > +{
> >> > > +    int i = 0;
> >> > > +
> >> > > +    while (idx / 32) {
> >> > > +        i++;
> >> > > +        idx -= 32;
> >> > > +    }
> >> > 
> >> > It is just me, or you are doing a division + modulus in a very strange 
> >> > way?
> >> > 
> >> >    i = idx / 32;
> >> >    idx = idx % 32;
> >> > 
> >> > ???
> >
> > Er, sorry I left this out.
> >
> > That won't work for MAX_PORTS > 32.
> 
> Why not?

After a good night's sleep, I see that I was wrong :-)

You're right and I don't remember why I did it this way instead of just
using % from the start. Maybe I had a different way of storing it back
then; it's been a long time.

I also saw that I was wrong about the casts:

> > > +/* Readiness of the guest to accept data on a port */
> > > +static int vcon_can_read(void *opaque)
> > > +{
> > > +    VirtIOConsolePort *port = (VirtIOConsolePort *) opaque;
> > 
> > Cast is not needed here.

> This is original code that I've not modified (just moved around).

> But you're right; I could do that in this patch itself.

These were indeed introduced by me (and are now corrected).

Thanks!

                Amit