Re: [oc] Verilog coding style for Open Cores-RTL - Case in point SHA1

[Tom Hawkins <tom1@launchbird.com>]

On Thursday 29 May 2003 10:51 am, Shehryar Shaheen wrote:
> To say SystemC is not a Concurent but a Sequential
>  language is a misleading statement and is perhaps bad
>  understanding of SystemC.
>
> Most simulators are single kernel simulators but in SystemC the
>  kernel is built into the executable binary which gives the
>  concurency similar to the verilog 'always' or the VHDL 'process'
> block.
>
> A  sample verilog module with two always block like.....
>
> module xyz(din1,din2, clock, dout1,dout2);
> input din1;
> input din2;
> input clock;
> output dout1;
> output dout2;
>
> reg dout1;
> reg dout2;
>
> always @(posedge clock)
> dout1 <= din1;
> always @(posedge clock)
> dout2 <= din2;
>
> endmodule
>
> ......... would look like the following in SystemC
>
> SC_MODULE(xyz)
> {
> sc_in<bool> din1;
> sc_in<bool> din2;
> sc_in<bool> clock;
> sc_out<bool> dout1;
> sc_out<bool> dout2;
> void func1()
> {
> dout1 = din2;
> };
> void func2()
> {
> dout2 = din2;
> };
>
> SC_CTOR(xyz)
> {
> SC_METHOD(func1);    <-----+
> sensitive_pos << clock;              |---- Both these functions
> will now execute concurently when this module is instantiated
> SC_METHOD(func2);    <-----+
> sensitive_pos << clock;
> }
> };
>
> This is just an example with no useful logic implemented in the
> modules but its just to show that functions registed as
>  SC_METHOD in the constructor (SC_CTOR) are equivalent to the
> Verilog always or VHDL process blocks

I don't know SystemC, but it appears parallelism is only explicit, 
i.e., you have go through an API to declare concurrent processes.  Is 
this true?  Is there any quickly way to code a netlist given a 
handful of components without having to worry about execution order?  
This is probably the main reason RTL designers prefer their HDL.

Line counts for xyz:
  SystemC = 23 lines
  Verilog = 13 lines
  Confluence = 5 lines:

Xyz <-
  comp +Din1 +Din2 -Dout1 -Dout2
    {Reg, 1 Din, Dout}
    {Reg, 1 Din, Dout}
  end

 

-- 
Tom Hawkins
Launchbird Design Systems, Inc.
952-200-3790
tom1@launchbird.com
http://www.launchbird.com/


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