MODULE selectadd;
(*---------------------------------------------------------
File name: selectadd.pm
Author: MM,AG
Date: 5/23/05 

Problem: This program adds all of the selected elements from 
L1 and L2 into L3. It uses MOD for the selection of the elements.
	(L1 + L2)<<MOD N>> = L3
	
Example of Execution:
	L1:  1  3  5  7  9 11 13 15 17 19 21 23 25 27 29 31
	L2:  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1
	L3:  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0
	N=2    || position MOD N
	L3:  0  4  0  8  0 12  0 16  0 20  0 24  0 28  0 32

Cycles:
1 addition.
*)
(*----------------------------------------------------------
		CONFIGURATION
----------------------------------------------------------*)
CONST  MAXCELLS=1024; (* MAXCELLS cells in one line *)

CONFIGURATION chain[0..(MAXCELLS - 1)];
CONNECTION
		left: chain [i] -> chain[(i-1) MOD MAXCELLS];
		right: chain[i] -> chain[(i+1) MOD MAXCELLS];
(*----------------------------------------------------------
		VARIABLES
----------------------------------------------------------*)
VAR 
		L0, L1, L2, L3: chain OF INTEGER;
		N, RightLimit: INTEGER;
(*----------------------------------------------------------
		MAIN
----------------------------------------------------------*)
BEGIN
	(*Initialize data *)
	RightLimit:= 16;
	N:= 2;
	L1:= ID(chain)* 2 - 1;	(* L1 = 1 3 5 7 9 11.. *)
	L2:= 1;     		(* L2 = 1 1 1 1 1 1.. *)
	L3:= 0;		(* L3 = 0 0 0 0 0 0.. *)
	
	(*Prepare selection *)
	L0:= ID(chain);	(* L0 = 1 2 3 4 5 6.. *)
	
	IF L0 <= RightLimit THEN  
		(*printing *)
		WriteString("L1: "); WriteInt(L1, 2);WriteLn;
		WriteString("L2: "); WriteInt(L2, 2);WriteLn;
		WriteString("L3: "); WriteInt(L3, 2);WriteLn;
		
		IF L0 MOD N = 0 THEN  	(* select even positions *)
			L3 := L1 + L2;		(* add selected positions *)
		END; (*IF *)
		
		(*printing *)
		WriteString("N=2    || position MOD N"); 
		WriteLn; WriteLn;
		WriteString("L3: ");WriteInt(L3, 2);WriteLn;
	END; (*IF *)
END selectadd.