binding issue

[meera]

hi,

 iam new to systemc, i tried programming AND but was felt with port binding issue. could anyone pls tell me where i have gone wrong...

 

 and.h

#include "systemc.h"

 

SC_MODULE(and)

{

sc_in< sc_uint<1> > a, b;

 

sc_out< sc_uint<1> > s;

void my_and()

{

s.write(a.read() & b.read());

cout<<s<<endl;

 }

 

SC_CTOR(and){

SC_METHOD(my_and);

sensitive << a << b;

}

};

 

 

 

and.cpp

 

 

#include "and.h"

 

int sc_main(int argc, char* argv[])

 

{

sc_signal<sc_uint<1> > a,b;

     sc_signal<sc_uint<1> >   s;

and d1("and");

 

d1.a(a);

d1.b(;

d1.s(s);

 

sc_start();

return 0;

}

 

[apfitch]

Could you post the error message please?

Alan

[dakupoto]

 

hi,

 iam new to systemc, i tried programming AND but was felt with port binding issue. could anyone pls tell me where i have gone wrong...

 

 and.h

#include "systemc.h"

 

SC_MODULE(and)

{

sc_in< sc_uint<1> > a, b;

 

sc_out< sc_uint<1> > s;

void my_and()

{

s.write(a.read() & b.read());

cout<<s<<endl;

 }

 

SC_CTOR(and){

SC_METHOD(my_and);

sensitive << a << b;

}

};

 

 

 

and.cpp

 

 

#include "and.h"

 

int sc_main(int argc, char* argv[])

 

{

sc_signal<sc_uint<1> > a,b;

     sc_signal<sc_uint<1> >   s;

and d1("and");

 

d1.a(a);

d1.b(;

d1.s(s);

 

sc_start();

return 0;

}

Hello,

Please provide the error message.

 

In your SC_MOULE declaration/definition for the 'and' gate,

have you tried:

 

sc_in< sc_uint<1> > a;

sc_in< sc_uint<1> > b;

 

Instead of(as you have rioght now):

sc_in< sc_uint<1> > a, b;

 

 

In your "int sc_main" I am afraid you do not 

insert any values into your signal lines for

the 'and' module to operate on.

 

Finally, please check out some new book on

SystemC -- unfortunately the material available

on some Web sites is hopelessly outdated, with

the authors being too lazy to update them.

 

Hope this helps.

[meera]

hi,

 thanks for replying . well iam now not getting any error messages (for the program)but as you said i havent inserted values in sc_main, can you pls elaborate on that point as to how to do that , is it not possible to assign values in cmd.exe window? iam using visual studio 2012. as one of the member has pointed out i tried separating the lines, but it didnt help.

[meera]

d1.a(a);

d1.b(;

d1.s(s);

a=1;

b=1;

sc_start(20,SC_NS);

return 0;

}

 

is it like this? becoz iam not getting output

[apfitch]

Hi Meera,

   you need to apply some stimulus, preferably with time delays between each stimulus change. I recommend writing a stimuls module. Have a look at http://www.doulos.com/knowhow/systemc/tutorial/modules_and_processes/especially the part about "testbench",

 

regards

Alan

[meera]

hi,

thanks alan. Could you tell me how to provide values to the variable in sc_main , upon using read() in your .cpp file

[apfitch]

Hi Meera,

  sorry I don't understand your question. But you can assign values to variables in sc_main like you did earlier, i.e.

d1.a(a);
d1.b(;
d1.s(s);
a=1;
b=1;
sc_start(20,SC_NS);
return 0;
}

But if you don't want to write a separate stimulus module, then you probably want to assign more values, i.e.

  a=1;
  b=1;
  sc_start(20,SC_NS);
  a = 0;
  sc_start(20,SC_NS);
  b = 0;
  sc_start(20, SC_NS);
  a = 1;
  sc_start(20, SC_NS);
  return 0;
}

regards

Alan

[meera]

hi Alan,

    i got your point, and have added to my program the lines you have suggested but still am not able get the output. I think iam missing something in my program that should call the operation "s" to perform. Could pls go through the program ? and suggest as to what can be done.

 

#include "systemc.h"

 

SC_MODULE(and) {

 

 

  sc_in<sc_uint <1> >a;

  sc_in<sc_uint <1> >b;

  sc_out<sc_uint <2> >s;

 

void my_and() {

 

 

s.write( a.read() | b.read());

cout<<a<<endl;

cout<<b<<endl;

cout<<s<<endl;

             }

SC_CTOR(and){

SC_THREAD(my_and);

 

sensitive << a <<b;

 

        }

 

};

 

 

#include "systemc.h"

#include "and.h"

 

int sc_main(int argc, char* argv[])

 

{

 

sc_signal<sc_uint <1> > a ;

sc_signal<sc_uint <1> > b ;

    sc_signal<sc_uint <2> > s ;

 

 

and d1("And");

d1.a(a);

d1.b(;

d1.s(s);

a=1;

b=1;

sc_start(20,SC_NS);

  a = 0;

  sc_start(20,SC_NS);

  b = 0;

  sc_start(20, SC_NS);

  a = 1;

  sc_start(20, SC_NS);

  return 0;

}

 

 

  

thank you

[apfitch]

OK, you've changed your original my_and to an SC_THREAD. I would change it back to an SC_METHOD,

 

regards

Alan

[meera]

hi Alan,
 
I changed it to SC_METHOD. But for any combination of input ie a&b iam getting "s" =0.

[dakupoto]

hi Alan,

 

I changed it to SC_METHOD. But for any combination of input ie a&b iam getting "s" =0.

 

Hello,

Please change the template to "bool" from "sc_uint".  Compile and try. Will work.

[apfitch]

Hi Meera,

 it works for me...

#include "systemc.h"

SC_MODULE(And) {


    sc_in<sc_uint <1> >a;
    sc_in<sc_uint <1> >b;
    sc_out<sc_uint <2> >s;

    void my_and() {
        s.write( a.read() | b.read());
        cout<<a<<endl;
        cout<<b<<endl;
        cout<<s<<endl;
    }

    SC_CTOR(And){
    SC_METHOD(my_and);

    sensitive << a <<b;

    }

};


#include "systemc.h"

int sc_main(int argc, char* argv[])
{

    sc_signal<sc_uint <1> > a ;
    sc_signal<sc_uint <1> > b ;
    sc_signal<sc_uint <2> > s ;


    And d1("And");
    d1.a(a);
    d1.b(;
    d1.s(s);
    a=1;
    b=1;
    sc_start(20,SC_NS);
    a = 0;
    sc_start(20,SC_NS);
    b = 0;
    sc_start(20, SC_NS);
    a = 1;
    sc_start(20, SC_NS);
    return 0;
}

Result

1
1
0
0
1
1
0
0
1
1
0
0

Of course it does an | as you'd changed it from an &

[meera]

hi Alan,

 iam getting the same output , but dont you think of the first set when a=1b=1 you are getting s=0 ? what i feel is that for current combination of a,b the result for s is seen in next step. Pls correct me if iam wrong.

 

thanks

[meera]

Hello,

Please change the template to "bool" from "sc_uint".  Compile and try. Will work.

 Hi,

i did try doing that , but as i pointed out i feel result of "s" is seen only in the next cycle...what should i do for that?

[dakupoto]

 Hi,

i did try doing that , but as i pointed out i feel result of "s" is seen only in the next cycle...what should i do for that?

 

Hello,

I am not sure at all what exactly you mean by "cycle". Please note that the AND operation is a 

pure combinational logic operation, and has nothing to do with any clock. That is why, when

combinational logic circuits are simulated, some values are added to the signal lines, and the

simulation is run for fixed time period, independent of the combinational logic circuit -- no clock

synchronization is required. Please be very clear about what you are doing or trying to achieve.

[meera]

hi,

if u execute is u will get to know what iam trying to say as .cpp 

#include "systemc.h"

#include "and.h"

 

int sc_main(int argc, char* argv[])

{

 

    sc_signal<sc_uint <3> > a ;

    sc_signal<sc_uint <3> > b ;

    sc_signal<sc_uint <3> > s ;

 

 

    and d1("And");

    d1.a(a);

    d1.b( ;

    d1.s(s);

    a=3;

b=4;

    sc_start(20,SC_NS);

    a = 1;

b = 2;

    sc_start(20,SC_NS);

a = 3;

    b = 4;

sc_start(20, SC_NS);

    a = 4;

b = 2;

    sc_start(20, SC_NS);

a = 1;

b = 1;

sc_start(20, SC_NS);

    return 0;

}

[meera]

Hello,

I am not sure at all what exactly you mean by "cycle". Please note that the AND operation is a 

pure combinational logic operation, and has nothing to do with any clock. That is why, when

combinational logic circuits are simulated, some values are added to the signal lines, and the

simulation is run for fixed time period, independent of the combinational logic circuit -- no clock

synchronization is required. Please be very clear about what you are doing or trying to achieve.

sorry yes u r correct. but if you could execute the lines in my recent post probably you might understand what iam trying to say.

[apfitch]

Hi Meera,

   signals update on the following delta, so when you print the value you print the current value, not the value that will be assigned when the process suspends.

 

The simplest way to make your code print out the final values of the signals would be to put the $display in a separate SC_METHOD, sensitive to s,

 

regards

Alan

 

Edit: oops too much SystemVerilog - I meant cout of course :-)

[meera]

Hi Meera,

   signals update on the following delta, so when you print the value you print the current value, not the value that will be assigned when the process suspends.

 

The simplest way to make your code print out the final values of the signals would be to put the $display in a separate SC_METHOD, sensitive to s,

 

regards

Alan

Hi Alan,

   Now iam able to see the correct output. Thanks for  helping me out with the issues.

 

thank you

Meera