MODULE exo4;
(* ----------------------------------------------------------------------
   exo4.pm
   D. Thiebaut
   Computes the value of a polynomial of degree 4 in a chain of PEs.
   The number of PEs is defined by N.
   The coefficients are stored in a vector array called coefs.
   The value x is given by the ID of the PE in which it resides.
   The result of the polynomial evaluation is saved in y at the end of
   the computation.
   ---------------------------------------------------------------------- *)
CONST N=8;

CONFIGURATION chain[0..N-1];
CONNECTION
    (* no connection needed *);

VAR
    coefs   : chain OF ARRAY[0..4] OF INTEGER;
    x, y    : chain OF INTEGER;

BEGIN
    (*--- initialization ---*)
    x := ID( chain );
    WriteString( "    x = " );
    WriteInt( x, 2 );

    (*--- coefficients ---*)
    coefs[0] := 1;
    coefs[1] := 1;
    coefs[2] := 1;
    coefs[3] := 1;
    coefs[4] := 1;

    (*--- parallel computation of the polynomials            ---*)
    (*--- (can be made more efficient using horner's method) ---*)
    y := ( x**4 ) * coefs[4] + ( x**3 ) * coefs[3] + ( x**2 ) * coefs[2]
        + x * coefs[1] + coefs[0];


    (*--- output ---*)
    WriteString( "    y = " );
    WriteInt( y, 2 );


END exo4.