Setting the vector length in SystemC with a received parameter - systemc

Question

Im making a xor gate in SystemC, from the binding of four NAND gates. I want the module to receive a vector of N bits, where N is passed as parameter. I should be able to perform & and not bitwise operations (for the NAND gate).
The best solution may be using sc_bv_base type, but I don't know how to initialize it in the constructor.
How can I create a bit vector using a custom length?

Answer 1

A way to parameterise the module is to create a new C++ template for the module.
In this example, the width of the input vector can be set at the level of the instantiation of this module
#ifndef MY_XOR_H_
#define MY_XOR_H_
#include <systemc.h>
template<int depth>
struct my_xor: sc_module {
sc_in<bool > clk;
sc_in<sc_uint<depth> > din;
sc_out<bool > dout;
void p1() {
dout.write(xor_reduce(din.read()));
}
SC_CTOR(my_xor) {
SC_METHOD(p1);
sensitive << clk.pos();
}
};
#endif /* MY_XOR_H_ */
Note that the struct my_xor: sc_module is used i.s.o. the SC_MODULE macro. (See page 40 , 5.2.5 SC_MODULE of the IEEE Std 1666-2011).
You can test this with the following testbench:
//------------------------------------------------------------------
// Simple Testbench for xor file
//------------------------------------------------------------------
#include <systemc.h>
#include "my_xor.h"
int sc_main(int argc, char* argv[]) {
const int WIDTH = 8;
sc_signal<sc_uint<WIDTH> > din;
sc_signal<bool> dout;
sc_clock clk("clk", 10, SC_NS, 0.5); // Create a clock signal
my_xor<WIDTH> DUT("my_xor"); // Instantiate Device Under Test
DUT.din(din); // Connect ports
DUT.dout(dout);
DUT.clk(clk);
sc_trace_file *fp; // Create VCD file
fp = sc_create_vcd_trace_file("wave"); // open(fp), create wave.vcd file
fp->set_time_unit(100, SC_PS); // set tracing resolution to ns
sc_trace(fp, clk, "clk"); // Add signals to trace file
sc_trace(fp, din, "din");
sc_trace(fp, dout, "dout");
sc_start(31, SC_NS); // Run simulation
din = 0x00;
sc_start(31, SC_NS); // Run simulation
din = 0x01;
sc_start(31, SC_NS); // Run simulation
din = 0xFF;
sc_start(31, SC_NS); // Run simulation
sc_close_vcd_trace_file(fp); // close(fp)
return 0;
}
Note that I'm using a struct and not a class. A class is also possible.
class my_xor: public sc_module{
public:
The XOR in this code is just the xor_reduce. You can find more about in the IEEE Std 1666-2011 at page 197 (7.2.8 Reduction operators). But I assume this is not the solution you wanted to have.