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(W170) Object cannot be traced Warning


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Hi everyone,

I am new to SystemC and I am trying to use the tracing functionality but I get the mentioned error, can anyone give some hints?

Thankx

Here is the message:

Info: (I703) tracing timescale unit set: 1 ns (my_trace.vcd)

Warning: (W710) object cannot not be traced: Fifo_data
In file: tracing/sc_trace.cpp:145


 

Here is the code:

#include <systemc.h>
#include <string>
using namespace std;
#define LENGTH 10
 
// Declaration de l'objet de tracage
sc_trace_file *trace_file;
 
struct write_if : virtual sc_interface
{
virtual void write(string) = 0;
virtual void reset() = 0;
};
 
struct read_if : virtual sc_interface
{
virtual void read(string &) = 0;
virtual int num_available() = 0;
};
 
struct fifo : sc_channel, write_if, read_if
{
fifo(sc_module_name name) : sc_channel(name), num_elements(0), first(0)
{
sc_trace(trace_file, data, "Fifo_data");
sc_trace(trace_file, num_elements, "Num_elements");
sc_trace(trace_file, first, "First");
}
 
void write(string s)
{
if (num_elements == max)
wait(read_event);
 
data[(first + num_elements) % max] = s;
++num_elements;
write_event.notify();
}
 
void read(string &s)
{
if (num_elements == 0)
wait(write_event);
 
s = data[first];
--num_elements;
first = (first + 1) % max;
read_event.notify();
}
 
void reset() { num_elements = first = 0; }
 
int num_available() { return num_elements; }
 
void end_of_simulation() {
cout << "fifo::end_of_simulation()" << endl;
sc_close_vcd_trace_file(trace_file);
}
 
protected:
enum e
{
max = 10
};
string data[max];
int num_elements, first;
sc_event write_event, read_event;
};
 
struct producer : sc_module
{
sc_port<write_if> out;
 
SC_HAS_PROCESS(producer);
 
producer(sc_module_name name) : sc_module(name)
{
SC_THREAD(main);
}
 
void main()
{
while (i < LENGTH)
out->write(words[i++]);
 
}
 
void end_of_simulation() {
cout << "producer::end_of_simulation()" << endl;
sc_close_vcd_trace_file(trace_file);
}
 
private:
int i = 0;
const string words[LENGTH] = {
"Visit", "www.accellera.org", "and", "see", "what",
"SystemC", "can", "do", "for you", "today!\n"
};
 
};
 
struct consumer : sc_module
{
sc_port<read_if> in;
 
SC_HAS_PROCESS(consumer);
 
consumer(sc_module_name name) : sc_module(name)
{
SC_THREAD(main);
}
 
void main()
{
string s;
cout << endl
<< endl;
 
while (true)
{
in->read(s);
cout << s << flush;
 
if (in->num_available() == 1)
cout << "<1>" << flush;
if (in->num_available() == 9)
cout << "<9>" << flush;
}
}
 
void end_of_simulation() {
cout << "consumer::end_of_simulation()" << endl;
sc_close_vcd_trace_file(trace_file);
}
 
};
 
struct top : sc_module
{
fifo *fifo_inst;
producer *prod_inst;
consumer *cons_inst;
 
top(sc_module_name name) : sc_module(name)
{
fifo_inst = new fifo("Fifo1");
 
prod_inst = new producer("Producer1");
prod_inst->out(*fifo_inst);
 
cons_inst = new consumer("Consumer1");
cons_inst->in(*fifo_inst);
}
 
void end_of_simulation() {
cout << "top::end_of_simulation()" << endl;
sc_close_vcd_trace_file(trace_file);
}
 
};
 
int sc_main(int, char *[])
{
trace_file = sc_create_vcd_trace_file("my_trace");
trace_file->set_time_unit(1, SC_NS);
 
top top1("Top1");
sc_start(SC_ZERO_TIME);
 
return 0;
}

 

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  • skander turki changed the title to (W170) Object cannot be traced Warning

The simple answer is that SystemC does not know how to trace std::string, and much less and array of std::string.

First, std::string is a dynamically variable array of characters, which will perplex waveform viewing because you need a fixed number of signals to display.

Changing to a fixed std::array<char,10> would help. You would still need to write an overload something like:

template<int depth>
void sc_trace( sc_trace_file* tf, const std::array<char,depth>& A, const std::string& name )
{
  // Code to trace individual char's
  for(int i=0; i<depth; ++i) {
    string elt_name = name + "["s + to_string(i) + "]s"; //< using modern C++14
    sc_trace( tf, A[i], elt_name );
  }
}

Even a simple array of int would need an overload.

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