Port binding for array of ports

[Gurmeet Singh Taank]

Hi Experts, 

How to achieve the port binding for array of vectors in system-C constructors?

I want to remove verilog modules and plug-in system-c modules into a big SV test-bench(basically to check the logic equivalence of SC model with RTL using RTL verification testcases). I cannot change the hierarchy of ports here(otherwise lots of RTL verification test cases may fail on the TB). I have already done this work for some modules and its working fine with Cadence Xcelium simulator. However some modules are using the array of bit vectors as their ports which I am not sure how to bind using the verilog shell around them while the port hierarchy is still maintained.

Here is a simple dummy example to ease the discussion on this topic:

SYSTEM-C MODEL

#include <systemc.h>

SC_MODULE(adder) {

sc_in<sc_uint<4> > a[3];
sc_in<sc_uint<4> > b[3];
sc_out<sc_uint<5> > c[3];

void m_add() {
    uint8_t i; 
    for(i=0;i<3;i++) {
        c.write(a.read() + b.read()); 
    }
}

SC_CTOR(adder):a("a"),
b("b"),
c("c"){

SC_METHOD(m_add); 
int i =0; 
for(i=0;i<=2;i++) {
sensitive << a << b;
}
}

~adder() { } 

};
XMSC_MODULE_EXPORT(adder);

VERILOG SHELL AROUND SYSTEM-C MODEL

module adder(input [2:0][3:0] a,
             input [2:0][3:0] b,
             output [2:0][4:0] c)

(* integer foreign      = "SystemC"; *);

/*
genvar i;
generate 
for(i=0;i<=2;i++) begin
    assign c = a + b; 
end
endgenerate
*/

endmodule

VERILOG TESTBENCH

module adder_tb(); 

reg [2:0][3:0] a; //Array of vectors
reg [2:0][3:0] b;//Array of vectors
wire [2:0][3:0] c; //Array of vectors

adder adder0(
.a(a[2:0]),
.b(b[2:0]),
.c(c[2:0])
);

initial begin 
    a = #1 2; 
    b = #1 3; 
    a = #10 2; 
    b = #10 3; 
    a = #15 15; 
    b = #15 15; 
    a = #20 9; 
    b = #21 15; 
end

endmodule

[Eyck]

First: you forgot the indicees into the arrays in your constructor and method.

Second: the constructor of adder will not work.  'a' as well as the other ports are plain arrays of e.g. sc_in<sc_uint<4> > which does not have any constructor (and does not call any constructor of the elements). You may use as std::vector but this does not really solve the issue as std::vector just calls the default constructor of the element. You should use sc_core::sc_vector which allows named initialization as well as hierarchical binding:

SC_MODULE(adder) {

 sc_core::sc_vectory<sc_in<sc_uint<4> > > a;
 sc_core::sc_vectory<sc_in<sc_uint<4> > > b;
 sc_core::sc_vectory<sc_out<sc_uint<5> > > c;


  void m_add() {
    for(size_t i=0;i<3;i++) {
        c[i].write(a[i].read() + b[i].read()); 
    }
  }

  SC_CTOR(adder):a("a", 3), b("b", 3), c("c", 3){

    SC_METHOD(m_add); 
    for(size_t i=0;i<3;i++) {
      sensitive << a[i] << b[i];
    }
  }

  ~adder() { } 

};

I don't know if Xcelium supports sc_vectors but I guess it does.

HTH

[Gurmeet Singh Taank]

Thanks Eyck, With the use of vectors, adder.v and adder.cpp are compiling successfully. However if I instantiate the adder.v into my TB its still throwing elaboration error. Please have a look at the attachments.

 

[Eyck]

As I wrote, I do not know Xcelium. But I would check the error in bpad_10634.err...

[Gurmeet Singh Taank]

Eyck, Earlier bpad_10634.err error was due to the mismatching port widths, I corrected that issue.

As per a document, Xcelium implements the IEEE1666-2011 standard for System-C which includes the sc_vector as well. I might be doing something wrong here on specific version usage or improper use of macros/command line options. I have raised a support ticket with Cadence on the sc_vector support in Xcelium.

1.       Independently module is compiling with xrun –sysc –sv adder.cpp adder.v (please find the “module_standalone” file attached)

xrun -sysc -sv -clean -disable_sem2009 adder.cpp adder.v >> module_standalone

2.       When instantiating in the top level adder_tb module elab step is failing (please find the “with_verilog_tb” file attached)

xrun -sysc -sv -clean -disable_sem2009 adder.cpp adder.v adder_tb.v >> with_verilog_tb

adder.cpp adder.v adder_tb.v module_standalone with_verilog_tb

[Gurmeet Singh Taank]

Hi Eyck, 

I will be using this workaround(at the cost of one extra hierarchy).

Regards,

Gurmeet