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Re: [ns] Creating new variable in c++ & accessing via TCL??

Hello!


What you've forgotten is to bind the variable in mac-802_11.cc :

bind("collision_count_", &collision_count);

There are also some other function available to bind variables suitable for bandwidth etc. Check the manual section 3.4.2.

/Håkan

Susan Tsao wrote:

Hello,

I created a new variable in mac-802_11.*  file, which I like to access
via
my TCL script. However, it doesn't work. Can someone please tell me
what I did wrong?
------------------------------------------------------------------------
---------------------------------

I created a variable called 'collision_count' which counts the number of

mac-802_11 collisions.  And I like to access this value at the end of my
simulation.

3 steps:

1) Added following line to mac-802_11.h:

        class Mac802_11 : public Mac {
                private:
                        int  collision_count;           // added a
private data memeber
        };

2) Changes to mac-802_11.cc:
        a) Initialize collison_count =0 in the constructor
Mac802_11::Mac802_11( )
        b) Increment "collision_count"  as follows

        Mac802_11::collision(Packet *p)  {

           if(TX_Time(p) > mhRecv_.expire()) {
                        mhRecv_.stop();
                        discard(pktRx_, DROP_MAC_COLLISION);
                collision_count+=1;                     // **** i  added
this line
                        pktRx_ = p;
                        mhRecv_.start(TX_Time(pktRx_));
                }
                else {
                        discard(p, DROP_MAC_COLLISION);
                collision_count +=1;                    // **** i added
this line
                }

3) My simulations consists of several wireless node sending packets to a
base station.
    And I want to access "colllision_count" at the end of my
simulations, so I have following
    in my TCL script.

set macobject [new Mac/802_11]
$ns_ at $simulation_endtime "count"

proc count {} {
        global macobject
        set colcount [$macobject set collision_count]
        puts "$count"
}

4) run my scripts, but it outputs errors:

ns: count: can't read "collision_count": no such variable
    while executing
"subst $[subst $var]"
    (procedure "_o156" line 5)
    (SplitObject set line 5)
    invoked from within
"$macobject set collision_count"
    (procedure "count" line 3)
    invoked from within
"count"

Has anyone done something similar to other classes?
Any help is appreciated!

Thanks.

susan

-- 
Håkan Byström, Operax
+46 920 755 07, office
+46 70 374 03 24, cellular