On Friday 04 February 2005 14:40, Timothy Miller wrote:
> On Fri, 4 Feb 2005 14:22:56 -0500, Daniel Phillips 
<[EMAIL PROTECTED]> wrote:
> > On Friday 04 February 2005 12:01, Daniel Phillips wrote:
> > > It appears that it's impossible to do 16-bit integer adds or
> > > subtracts in 5ns on a Spartan 3.  Usually, when you are just
> > > pipelining everything, that's no big deal.  Just split the math
> > > into 8-bit stages.  (I've done it plenty of times.) 
> > > Unfortunately, there are two parts of the design, the vertical
> > > and horizontal rasterizers, that make it a bit challenging in
> > > that regard.
> >
> > Hi Timothy,
> >
> > I'm trying to understand what you mean by this.  I imagined that it
> > doesn't matter how many stages it takes to step to the next
> > horizontal pixel pair, because you're only concerned about
> > throughput, not latency.  I must have missed something.
>
> You have a single chunk of logic that must iterate over pixel pairs.
> In order for it to know what to compute for one cycle, it must know
> the result of the previous cycle.  If the computation takes more than
> one cycle, then it cannot iterate once per cycle. Latency becomes
> throughput.

But why can't we solve this with an intermediate queue that holds the 
same number of entries as stages in the iteration?

Regards,

Daniel
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