Mine

// gen1.cpp code
// This file implements functionality for the generator module

#include <omnetpp.h>

class Generator: public cSimpleModule
{
    // This is a macro; it expands to constructor definition.
    Module_Class_Members(Generator, cSimpleModule, 8192);
                                 // 8192 - estimated stack size needs

    // The following redefined virtual function implements the
    // module functionality.
    virtual void activity();
};
// The module class needs to be registered with OMNeT++

Define_Module(Generator);

void Generator::activity()
{ 
 while(1)
  {
  cMessage *msg = receive();
  double temp; 
  int num_pkts = par("number_rand");
  double p1 = par("prob");
  for (int i=0; i<num_pkts; i++)
     {
       // create message
        cMessage *msg = new cMessage("packet");

      temp = (double)rand()/RAND_MAX;
      if (temp < p1)
        {
          ev << "Generate data packet\n"; 
          msg -> setKind(1);
        }
      else
	{
           ev << "Generate voice packet\n";
           msg -> setKind(0);
	}
      send(msg, "out");
      wait((double)ia_time);
    }
  }
}