- C and the Processor Instructions :

Let us now turns to the specification of the processor instructions we want to use. We use here a minimal set of instructions, of three kinds:

• The operators to access an array element or the component of a struct or an union :
  Syntax :

  

• The Arithmetic and Logic Operators :
  • Affectation Operator : =
    Syntax :

    

  • Arithmetic Operators :

    

  • Logical Operators : they return either 1 when true or 0 when false.

    

  Syntax :

  

  Comparing to the standard C-language several aspects have been restrained here:

  • No implicit cast is allowed, since -in practice- this sometimes depends on the compiler implementation, although or should not.
  • When an undefined evaluation occurs, overflow, division by zero, cast to undefined value, etc.. an exception or signal will be issued, because undefined values are not acceptable here.
  • Arithmetic and comparison operators apply on int and float operands, but logic operators apply on int operands only. Implicit casts, defined in standard-C, allows such extensions.
• The conditional, switch and particular loop instruction :\ Here we consider the following operators :
  • conditional operator :
    if(expr){ ... } else { ... }
  • switch operator :
    switch name { case val1 : ; default: }
  • particular form of the loop operator :
    for(int i = a; i b; i = i c).
  Syntax :

  

  The main feature here is that we allow either conditional statements though the if and switch constructs, or a very particular kind of loop for which we can verify if it finishes and how many iterations will be performed.