Parameterized precompiled modules

[Niiranen Miika]

Hi all!

I'm wondering whether it is possible to use parameterized precompiled
modules in VHDL. If I recall correctly, in SystemC it was possible to
compile parameterized modules "in parallel" when the possible parameters
were known in advance. Say, a customer knows that he may want to use our
new adder with bus widths of 8, 16, and 32 bits. Is it possible to
automate the process of compiling (or even synthesizing) the adder for
these parameters, i.e., separate bit widths, so that these cases would not
have to be compiled and labeled separately? Giving the source VHDLs to the
client is not an option due to IP protection reasons. I use Synopsys
Design Compiler as a synthesis tool.

Sorry for this confusing explanation...

Miika Niiranen

 

[Jim Lewis]

Miika,
With Synopsys flow, I tend to do this with a wrapper.
My original rational was so I could have unique design
names after synthesis without having to rely on the
synthesis tool to generate the names and such, however,
it seems this technique would fit well in what you are
trying to do.

First I create the generic component. Then I instantiate
the generic component in a component with the generic
values specified.

Generic entity:
entity Mux2 is
generic (width : integer ) ;
port (
Sel : in std_logic ;
A : in std_logic_vector(width-1 downto 0) ;
B : in std_logic_vector(width-1 downto 0) ;
Y : in std_logic_vector(width-1 downto 0)
) ;
end Mux2 ;

.....

Wrapper Entity:
entity Mux2x8 is
port (
Sel : in std_logic ;
A : in std_logic_vector(7 downto 0) ;
B : in std_logic_vector(7 downto 0) ;
Y : in std_logic_vector(7 downto 0)
) ;
end Mux2x8 ;
architecture WRAPPER of mux2x8 is
component Mux2 ...

begin
u_mux2 : Mux2
generic map (8)
port map( Sel, A, B, Y) :

end WRAPPER ;

After synthesizing Mux2x8, I remove the hierarchy
generated by mux2 using the ungroup command.

Kind of brute force, but seems to simplify the
synthesis flow and is really the only option for
you to presynthesize the design and deliver only
the synthesized code. If you are creating customize
sizes alot, you should be able to do this with a
script.


Cheers,
Jim
--
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Jim Lewis
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