Re: [oc] Top-Down Vs Bottom-Up

[Shawn Tan <shawn.tan@aeste.net>]

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Hi!!
> Hi All,
>  
> My question may seem very trivial, but it is pretty tricky in my
> opinion.  I request to be corrected where ever I go wrong.
>  
> Question is:  In Basic Digital design, how do we distinguish Top-Down
> approach and bottom-up approach?  Will there be any difference in the
> RTL source files I obtain following these apporaches?  If no, then how

I would say that in my limited experience, you'll have different RTL
files with top-down and bottom-up approach though technically they
shouldn't be.. Whether topdown or bottomup, depends greatly on what goes
on in the head of the system architect.. 

Some people find it easier to think topdown, where they get to grasp the
bigger picture and then isolate and work on the specific functional
components.. some people find it easier to work bottomup, where they put
existing pieces of working subcomponents together to form the big
thing.. but I work both ways at the same time and I believe that a vast
majority of people use both approaches at the same time, switching from
topdown to bottomup and vice-versa depending on what mode the brain is
on at the time..

> Top-Down compile would mean I would read-in the whole of my design to
> the memory, apply my optimization constraints at the top-level only
> and then compile.  In case of a re-compilation, I would still have the
> top-module as my reference and apply attributes and constraints to my
> sub-designs using hierarchical definitions. Bottom-Up compile would
> mean I would read-in one sub-module at a time, with my
> sub-design-specific constraint files, compile each of them
> independantly, finally read-in my top-module, then link and compile
> with top-level constraints.  

Yup, that's the definition of topdown and bottomup compiles..

>  
> Thanks and Regards,
> R. Ramakrishna
> 
> 
> ---------------------------------
> Do you Yahoo!?
> Yahoo! SiteBuilder - Free, easy-to-use web site design software


- -- 
with metta,
Shawn Tan.
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