RE: [sv-bc] parameterized structures

OK, now define $typename and static casting for parameterized types.

 

Shalom

 

________________________________

From: Feldman, Yulik 
Sent: Thursday, June 15, 2006 1:34 PM
To: Bresticker, Shalom; 'sv-bc@server.verilog.org'
Subject: RE: [sv-bc] parameterized structures

 

Yes, but I don't see a problem with that. It is similar to how instances
of modules/classes/interfaces are determined. During the elaboration,
the compiler evaluates the parameter values and determines what
parameterization of the instantiated entity is used in each instance. In
the same way it can determine what parameterization of the
"instantiated" type is used in declaration of a variable. Technically,
maintaining/handling a list of used instantiated types in the design
should be no more complex than maintaining/handling a list of used
module/class/interface parameterizations. Abstractly speaking, all those
can be considered "types" of design objects; it just happened that
"types" of variables are called "data types", while types of module
instances, for example, are called "modules".

 

--Yulik.

 

________________________________

From: Bresticker, Shalom 
Sent: Thursday, June 15, 2006 1:19 PM
To: Feldman, Yulik; 'sv-bc@server.verilog.org'
Subject: RE: [sv-bc] parameterized structures

 

I did not mean parameterization at run-time. I mean that you use the
same type name, 'parameterized_struct', for two different types
simultaneously. You have not just instantiated the variable, you have
also instantiated the type as well.

 

Shalom

 

________________________________

From: Feldman, Yulik 
Sent: Thursday, June 15, 2006 1:13 PM
To: Bresticker, Shalom; 'sv-bc@server.verilog.org'
Subject: RE: [sv-bc] parameterized structures

 

No, I didn't mean that parameterization of structures should be done at
run-time. It should continue to happen at elaboration time, using
constant expressions. Once I declared variables with different
parameterization, like in the example below, I can easily use them all
at the same place. For example, I can write "ps1.m2 = ps2.m2". If the
parameterization is not local, writing a conceptually similar assignment
becomes much harder and less readable.

 

________________________________

From: Bresticker, Shalom 
Sent: Thursday, June 15, 2006 1:00 PM
To: Feldman, Yulik; 'sv-bc@server.verilog.org'
Subject: RE: [sv-bc] parameterized structures

 

So that is a change from now. Currently a given type may be
parameterized, but those parameters have a single value fixed at
elaboration time, so the type is unambiguously defined.

 

Shalom

 

________________________________

From: Feldman, Yulik 
Sent: Thursday, June 15, 2006 12:56 PM
To: Bresticker, Shalom; 'sv-bc@server.verilog.org'
Subject: RE: [sv-bc] parameterized structures

 

Yes. The locality has many advantages. For example, if my design needs
several parameterized structures, the ability to specify the parameters
locally to each structure makes the code more modular and readable,
avoiding the need to specify the conceptually unrelated parameters in
the parent construct or on the compilation unit level. Maybe even more
important, the ability to override the parameters locally makes it much
easier to use several parameterizations of the same structure
simultaneously.

 

--Yulik.

 

________________________________

From: Bresticker, Shalom 
Sent: Thursday, June 15, 2006 12:37 PM
To: Feldman, Yulik; sv-bc@server.verilog.org
Subject: RE: [sv-bc] parameterized structures

 

Even today, a structure can be parameterized (though I still think the
correct word would be 'parametric', but 'parameterized' sounds more
high-techy). Your idea just makes the parameter declaration local to the
structure declaration, no?

 

Shalom

 

________________________________

From: owner-sv-bc@server.eda-stds.org
[mailto:owner-sv-bc@server.eda-stds.org] On Behalf Of Feldman, Yulik
Sent: Thursday, June 15, 2006 12:23 PM
To: sv-bc@server.verilog.org
Subject: [sv-bc] parameterized structures

 

Hi,

 

I would like to get a general opinion of forum's experts on the idea to
introduce parameterized structures to SystemVerilog. Parameterized
structures are similar to regular structures, but allow
parameterization, like modules, classes and interfaces. The syntax
currently doesn't matter, but just to give a visual example:

 

typedef struct #(SIZE = 32, TYPE = integer) {

            bit [SIZE-1:0] m1;

            TYPE m2;

} parameterized_struct;

 

parameterized_struct ps1; // Default parameterization

parameterized_struct #(.SIZE(64), .TYPE(int)) ps2; // Overridden
parameterization

 

The ability to parameterize structures may be quite useful to raise the
abstraction level of the design. It is quite similar to how template
classes/structs in C++ help to raise the abstraction level of C++
programs. Parameterized structures, unlike parameterized modules and
interfaces, will be data types, which will allow their usage in wide
spectrum of coding scenarios (for example as operands of expressions).
Unlike parameterized classes, parameterized structures could be easily
used in design itself (vs. testbench code), without fear to open a can
of worms of object life time and scheduling semantics issues. And, on
top of that, there seems to be no problem to synthesize and/or formally
analyze the parameterized structures. 

 

So, please, let me know what you think about it.

 

Thanks,

            Yulik.