How to use a signal as function parameter in CAPL

I am trying to write a function in CAPL that takes a signal and calculates the physical value with the signal value, the signal factor and the signal offset.

This is how a simple gateway normally works:

message CAN1.myMessage1 myMessage1 = {DIR = RX};//message from the database
message CAN2.myMessage2 myMessage2 = {DIR = TX};//another message from the database

on message CAN1.*
{
   if(this.id == myMessage1.id)
   {
      myMessage1 = this;
      myMessage2.mySignalB = myMessage1.mySignalA * myMessage1.mySignalA.factor + myMessage1.mySignalA.offset;
   }
}

And this is what I am trying to do:

...
on message CAN1.*
{
   if(this.id ==myMessage1.id)
   {
      myMessage1 = this;
      myMessage2.mySignalB = PhysicalValue(myMessage1.mySignalA);
   }
}

double PhysicalValue(signal * s)
{
  return s*s.factor+s.offset;
}

There are two problems with this code:
Firstly when I pass the signal as the parameter the compiler says that the types don't match. The second problem is that inside the function the attributes (factor and offset) are no longer recognized. These problems might have something to do with the weird object-oriented-but-not-really nature of CAPL. The value of the signals can be accessed directly but it also has attributes?

int rawValue = myMessage1.mySignalA;

If you are familiar with C you might say that the problem is that I am specifying a pointer in the function but that I am not passing a pointer into it. But in CAPL there are no pointers and the * simply means anything. Without the * I would have needed to use a specific signal which would have defeated the purpose of the function.

EDIT:
I have found the attribute .phys by now which does exactly what my demo function would have done.

double physValue = myMessage1.mySignalA.phys;

This has already made my code much shorter but there are other operations that I need to perform for multiple signals so being able to use signals as a function parameter would still be useful.

Solution

What you can do is this:

double PhysicalValue(signal * s)
{
  // access signal by prepending a $
  return $s.phys;
}

Call like this

on message CAN1.*
{
   if(this.id ==myMessage1.id)
   {
      myMessage1 = this;
      myMessage2.mySignalB = PhysicalValue(CAN1::myMessage1::mySignalA);
   }
}

I.e. when you call your function, you have to provide the qualified name of the signal (with colons rather than dots). To my knowledge it is not possible to use myMessage1.mySignalA, since signals itself are not a CAPL datatype.

Apart from this, you might re-think whether you really should be using on message, but rather switch to on signal. Handling the signal values no matter with which message they are sent is done by CANoe's signal server.