(..Assignments (Var.))	Contents	Index	(Declaration Part..)

3. RDL - Retina Definition Language

After having a look at all the basic modules we need to create a RDL or SDL program, we will now try to understand their specific programming structures. Therefore, we certainly have to make a distinction between RDL and SDL. In this chapter we will start with RDL programs.

As already mentioned it is the aim of a RDL program to determine the retina of the CA, or in other words, to fix its spatial extension in for a certain , as well as to gain a valid initial configuration. But before doing this, it is also necessary to make some statements about the state set of the CA, in terms of SCARLET to determine the amount, the sequence and the types of the registers used.

Notice that the neighbourhood is of no importance for the retina and the initial configuration. That is the reason why it simply does not exist in RDL. So never use neighbours or components of them (registers) to form an expression in RDL, more precisely:

• CellExpression does not allow the use of NeighbourIdentifier,

• It is forbidden to take NeighbourIdentifier.IntRegIdentifier ( = IntReg) as an IntExpression as well as

• to use NeighbourIdentifier.StringRegIdentifier ( = StringReg) as a StringExpression.

From a formal point of view, a RDL program is divided up into a declaration part and a statement part:

(..Assignments (Var.))	Contents	Index	(Declaration Part..)