Re: [oc] FIFO or shared memory

[Steve Wilson <stevew@intrinsix.com>]

Jamil,

This is my two-cents worth on how I would architect such an interface...
and maybe part of my problem with what your describing below is a mix-up
in my terminology versus yours.  I think of a FIFO as fundamentally
being a dual-port structure. 

So let me first introduce what I think a dual-port structure for such an
application would look like.  

I'd assume it would look like a pure register file that allows reading
and writting simultaneously. Around this pure register file you would
put a write pointer, read pointer, byte(or word) counter, control and
synchronizing logic to create a uni-directional FIFO. 

I then would place two of these uni-directional FIFO structures, one for
read data, and one for write data, onto the data path.  I'd imagine that
depth would have to be at least two frames deep. You might even add a
Flag bit within the memory saying Frame boundary or some such.

Does this give you any ideas, or is it covering what you described
below?	

Steve Wilson


Jamil Khatib wrote:
> 
> Hi,
> For the HDLC controller core and all other
> communication controllers, what would be the best
> external memory buffering FIFO or shared memory?
> 
> Currently I have FIFO interface which is simpler but
> have limitation on the control of the Frame
> (datafragment) On shared dual port memory the
> interface will be harder but the Fragments will be
> organized in better way and it is easier to fetch them
> 
> What do you suggest? should I made the interface for
> teh controller generic and leave this option to the
> system intgreator to build the suitable interface ?
> 
> Regards
> Jamil Khatib
> 
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