MODULE genidn;
(*---------------------------------------------------------
File name: genidn.pm
Author: AG
Date: 5/31/05 

Problem: This program generates the identity matrix NxN
on an ARRAY of N lines. This program works if N is a power of
2.

Example of Execution:
	ArrLine[1]: 1  0  0  0  1  0  0  0  1  0  0  0  1  0  0
	ArrLine[2]: 0  1  0  0  0  1  0  0  0  1  0  0  0  1  0
	ArrLine[3]: 0  0  1  0  0  0  1  0  0  0  1  0  0  0  1
	ArrLine[4]: 0  0  0  1  0  0  0  1  0  0  0  1  0  0  0

Cycles:
1 ID + 1 MOD +2 assignments + (N - 1) shifts.
*)
(*----------------------------------------------------------
		CONFIGURATION
----------------------------------------------------------*)
CONST  MAXCELLS=1024; (* MAXCELLS cells in one line *)
CONST N=4;

CONFIGURATION chain[0..(MAXCELLS - 1)];
CONNECTION
		left: chain [i] -> chain[(i-1) MOD MAXCELLS];
		right: chain[i] -> chain[(i+1) MOD MAXCELLS];
(*----------------------------------------------------------
		VARIABLES
----------------------------------------------------------*)
VAR 
		L1: chain OF INTEGER;
		i: INTEGER; 
		ArrLine: ARRAY[1..N] OF chain OF INTEGER;
(*----------------------------------------------------------
		MAIN
----------------------------------------------------------*)
BEGIN
	(*Initialize data *)
	L1:= 0;
	
	(*generate master line *)
	IF ID(chain) MOD N = 1 THEN
		L1:= 1;			(* Put a 1 every N element *)
	END; (* IF *)
	ArrLine[1]:= L1;	(*copy master line into first line *)
	
	(*generate other lines *)
	FOR i:= 2 TO N DO 
		ArrLine[i] := RECEIVE.right(ArrLine[i-1]); (* shift by one on every following array *)
	END; (*FOR*)
	
	(* Printing *)
	IF ID(chain) < 16 THEN
		FOR i:= 1 TO N DO
			WriteString("ArrLine["); WriteInt(i, 0); WriteString("]:"); 
			WriteInt(ArrLine[i], 2); WriteLn;
		END; (*FOR*)
	END; (* display *)
END genidn.