Process sensitivity with sc_vector

[ElliottCB]

Greetings everyone,

I have a process that is sensitive to an sc_vector (specifically a vector of input ports) and was curious about how to handle the fact that values are maintained on each port in that vector on subsequent iterations of the process. This makes it very difficult to determine which values are actually new when the process is executed. I was hoping there would be a way to clear the value on a port once it had been read, but I could not find anything like this. The closest thing to a solution is to "latch" the value each time the process gets triggered and then compare the latch value with the port value to determine if anything new has arrived.

Is there a better way to do this? Thanks a bunch in advance.

[apfitch]

What kind of port are you using?

Alan

[Philipp A Hartmann]

Assuming you're using plain signal ports, you can use the event member function to check, whether a specific port has been triggered in the current delta cycle:

sc_vector< sc_in< int> > in_vec;
// ...
SC_METHOD(proc);
 for( unsigned i= 0; i<in_vec.size(); ++i )
sensitive << in_vec[i];
// ...
void proc() {
 for( unsigned i= 0; i<in_vec.size(); ++i )
if( in_vec[i]->event() )
  std::cout << "in_vec[" << i << "] triggered." << std::endl;
}

Greetings from Oldenburg,

Philipp

[ElliottCB]

Philipp,

This is 100% perfect. Thank you so much.

Elliott

[apfitch]

Hi Elliott,

one other thing - it's not clear from your original post what you mean by a new value - if you mean a change in value, then the event() method will tell you a value has changed *assuming* the ports are connected to sc_signal. If you want to detect an event even if the value hasn't changed (for instance if the same value is assigned twice) you can use the sc_buffer channel instead,

regards

Alan

[pablomtz]

Dear Philipp,

 

If I am using a sc_vector for clock inputs. How can I get the difference between pos and neg?

 

Suppose I have the following code:

 

 

 

sc_vector<sc_in_clk > port_vec;   //ports

....

SC_METHOD(do_sth);
for( unsigned i= 0; i<port_vec.size(); ++i ) sensitive << port_vec[i];    // Id like to do sth like this: sensitive << port_vec[i].pos();

...




void Producer::do_sth(void) {


for( unsigned clk_id= 0; clk_id<port_vec.size(); ++clk_id )
   if(port_vec[clk_id]->event())   //or like this: port_vec[clk_id]->pos()
      std::cout << "in_vec[" << clk_id << "] triggered." << std::endl;


}
 

 

 

Regards

Pablo

[Philipp A Hartmann]

Pablo,
 

SC_METHOD(do_sth);
for( unsigned i= 0; i<port_vec.size(); ++i ) sensitive << port_vec[i];    // Id like to do sth like this: sensitive << port_vec[i].pos();

 
This should just work as is.

 

if(port_vec[clk_id]->event())   //or like this: port_vec[clk_id]->pos()

 

Here you should use the posedge/negedge functions:

if(port_vec[clk_id]->posedge())   //or like this: port_vec[clk_id]->pos()

This is equivalent to:

if( port_vec[clk_id]->event() && port_vec[clk_id]->read() )

 
Greetings from Oldenburg,
  Philipp

[pablomtz]

Thank you Philipp! Its woking now!

 

Pablo

[DS1701]

Thanks @Philipp A Hartmann

How to use sc_vector with pointer?

sc_vector< sc_in< int> > *in_vec;

 

[Philipp A Hartmann]

 

3 hours ago, TRANG said:

How to use sc_vector with pointer?

sc_vector< sc_in< int> > *in_vec;

Why do you want to do this?

[DS1701]

2 minutes ago, Philipp A Hartmann said:

 

Why do you want to do this?

I think if use pointer, my code faster and save memory .

my project:

///APM.h
class APM: public sc_module
{

public:
    sc_in<bool>     clkAPM;
    sc_in<bool>              *IFA[4];
...

///APM.cpp
APM::APM(sc_module_name name)
        :sc_module(name)
	    // Initializing
        ,clkAPM("clkAPM")
{//{{{ 
    /// Initializing
    std::ostringstream port_name;
    for (unsigned int index = 0; index < 4; index++) {
        port_name.str("");
        port_name << "IFA" << index;
        IFA[index] = new sc_in<bool>(port_name.str().c_str());
        sc_assert(IFA[index] != NULL);
    }
    SC_METHOD(AMethod);
    dont_initialize();
    sensitive << (*IFA)[0];
...

I know this it old style code. So, I want to use sc_vector.

Thanks.