SC_METHOD and next_trigger() diagnostics

[katang 0]

I receive the message

Error: (E520) next_trigger() is only allowed in SC_METHODs:
        in SC_THREADs and SC_CTHREADs use wait() instead

when running my code (the relevant fragments are shown below). Any idea, what could be wrong? (what else is needed?)
 

SC_MODULE(scMemory) {
    sc_core::sc_in<bool> Clock;  

public:
    void WaitAccessing(void)
       {    next_trigger(memory_accessed); }
    void ReceivedClock(void);
  sc_event memory_accessed;    // memory access finished
};

SC_HAS_PROCESS(scMemory);
scMemory::scMemory(sc_core::sc_module_name nm, int Size )
: sc_core::sc_module(nm),  mClocks(0), Length(Size), my_state(STANDBY)
{
   SC_METHOD(ReceivedClock);
   sensitive << Clock.pos();
   SC_METHOD(WaitAccessing);
   sensitive << memory_accessed;
   dont_initialize();  // Do not receive clock during initialization
}

the error message changes to

 

Error: (E519) wait() is only allowed in SC_THREADs and SC_CTHREADs:

in SC_METHODs use next_trigger() instead

if I change the code to

   SC_THREAD(WaitAccessing);

    void WaitAccessing(void)
       {    wait(memory_accessed); }

I surely do something wrong, but surely the diagnostic messages are not on the top, too.

 

[Roman Popov 48]

Most likely you are calling WaitAccessing from somewhere else, not shown in your code sample.  Just set a breakpoint on error and check call stack.

Also, why do you put  SC_HAS_PROCESS to global namespace?

[katang 0]

Well, the full code of the member function calling WaitAccessing() is

    byte_t
  getByte(scCore* FromCore, SC_ADDRESS_TYPE  Address){ 
       AccessMemory(FromCore, scMemoryRead, Address, 1);  // Request a content
       WaitAccessing();
       return storage->contents[Address];
    }

Of course I set a breakpoint in the member function above (this is the only place where WaitAccessing() is called from)  and it is exactly called from this place. Concerning your namespace question:

I simple followed the example in SCFTGU, page 55

//FILE: module_name.cpp
SC_HAS_PROCESS(module_name);
module_name::module_name(
sc_module_name instname[, other_args…])
: sc_module(instname)

Is it wrong (or can be wrong)?

[Roman Popov 48]

Can you give a complete small reproducer of your problem? Otherwise I can just guess. Who calls getByte? Some sc_thread?

About SC_HAS_PROCESS - it should be fine unless you defne couple of modules in same translation unit. 

[katang 0]

OK, I will try to make an MWE. This module is part of a bigger project.

[David Black 123]

Re. SC_HAS_PROCESS

That would appear to be an error in the text. The best place to put SC_HAS_PROCESS is inside the constructor as the first line in the body of the constructor. It is syntactically legal there and the only things using it are the SC_METHOD, SC_THREAD, and SC_CTHREAD macros.

[David Black 123]

Re. the error

SC_METHOD is called repeatedly (every time an element of the static sensitivity list triggers); however, SC_METHOD processes must execute in single delta cycle (zero time). Blocking methods such as wait() is illegal there. Methods such as sc_fifo::write() call wait() and are therefore also illegal. To wait 10 ns, you can do something like this:

#include <systemc>
#include <iostream>
struct Ex1 : sc_core::sc_module
{
  Ex1( void )
  {
    SC_HAS_PROCESS(Ex1);
    SC_METHOD(Method10ns);
  }
  void Method10ns( void )
  {
    next_trigger( 10, SC_NS );
    std::cout << "Now " << sc_core::sc_time_stamp() << sdt::endl;
  }
};

SC_THREAD is called only one, and therefore normally contains an infinite loop to properly model hardware. Thus the above is coded more simply as:

#include <systemc>
#include <iostream>
struct Ex1 : sc_core::sc_module
{
  Ex1( void )
  {
    SC_HAS_PROCESS(Ex1);
    SC_THREAD(Thread10ns);
  }
  void Thread10ns( void )
  {
    for(;;) {
      std::cout << "Now " << sc_core::sc_time_stamp() << sdt::endl;
      wait( 10, SC_NS );

    }
  }
};