max_num_extensions

[Khushi]

Hi 

I am trying to understand the max_num_extension() return value. When I create a payload object and use set_extension and then call max_num_extensions(), then  it returns 2. 

I tried to debug and noticed that even if we didn't have any module, it still gives 2. The following piece of code prints 2. why it is so ?

//#include "top.hpp"
#include "tlm.h"
#include "systemc.h"
int sc_main(int argc, char** argv){
    std::cout<<tlm::max_num_extensions()<<std::endl;
    sc_start();
	return 0;
}

LRM@496 syas "The function max_num_extensions shall return the number of extension types, that is, the size of the extension array. As a consequence, the extension types shall be numbered from 0 to max_num_extensions()-1".

Thanks

Khushi

 

[Eyck]

Each type of extension has an automatically assigned ordinal number which is available per extension as ID in the base class tlm_extension. So in your case you have 2 tlm_extensions defined somewhere.

Under the hood this ID is used as an index into the m_extension array of the tlm::generic_payload.

Best

[Philipp A Hartmann]

Hi Khushi,

just adding to Eyck's answer, the "default" extensions in SystemC 2.3.3 are the following two implementation defined classes:

• tlm::tlm_endian_context
• tlm_utils::instance_specific_extension_carrier

Greetings from Duisburg,
  Philipp