MODULE count;
(*---------------------------------------------------------
File name: count.pm
Author: AG, MM
Date: 5/18/05 

Problem: This program counts the number of 0's on a line.
In this example, the line starts filled with random numbers.

Example of Execution:
	Line is:   4  5  5  7  2  4  2  1  4  5  0  9  3  5
	Number of 0:  1

Cycles:
1 assignment + 1 REDUCE
*)
(*----------------------------------------------------------
		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 
		L: chain OF INTEGER;  	(* Line always "L# *)	
		RightLimit, MaxVal, Count, Item: INTEGER;
(*----------------------------------------------------------
		MAIN
----------------------------------------------------------*)
BEGIN
	(* initializing data*)
	L := ID( chain );
	RightLimit := 15;
	MaxVal := 10;		(* Maximum value for random *)
	Item:=0; 			(* Item to count is 0 *)
	
	IF L < RightLimit THEN		(* work only in selected first 15 cells *)
		L := RandomInt(chain ) MOD MaxVal;  	(* Put random numbers in L *)
		
		(*printing*)
		WriteString( "Line is:  ");WriteInt( L  ,  2);WriteLn;
		
		IF L = Item THEN
			L:= 1;
			Count:= REDUCE.SUM( L );
		END; (* IF *)
		
		(*printing*)
		WriteString( "Number of 0: "); WriteInt(Count, 2);  

	END;  (* IF *)

END count.