//******************************************************************************
//
// File:    MSHistogramSmp2.java
// Package: edu.rit.smp.fractal
// Unit:    Class edu.rit.smp.fractal.MSHistogramSmp2
//
// This Java source file is copyright (C) 2008 by Alan Kaminsky. All rights
// reserved. For further information, contact the author, Alan Kaminsky, at
// ark@cs.rit.edu.
//
// This Java source file is part of the Parallel Java Library ("PJ"). PJ is free
// software; you can redistribute it and/or modify it under the terms of the GNU
// General Public License as published by the Free Software Foundation; either
// version 3 of the License, or (at your option) any later version.
//
// PJ is distributed in the hope that it will be useful, but WITHOUT ANY
// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
// A PARTICULAR PURPOSE. See the GNU General Public License for more details.
//
// Linking this library statically or dynamically with other modules is making a
// combined work based on this library. Thus, the terms and conditions of the
// GNU General Public License cover the whole combination.
//
// As a special exception, the copyright holders of this library give you
// permission to link this library with independent modules to produce an
// executable, regardless of the license terms of these independent modules, and
// to copy and distribute the resulting executable under terms of your choice,
// provided that you also meet, for each linked independent module, the terms
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// module which is not derived from or based on this library. If you modify this
// library, you may extend this exception to your version of the library, but
// you are not obligated to do so. If you do not wish to do so, delete this
// exception statement from your version.
//
// A copy of the GNU General Public License is provided in the file gpl.txt. You
// may also obtain a copy of the GNU General Public License on the World Wide
// Web at http://www.gnu.org/licenses/gpl.html.
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//******************************************************************************

package edu.rit.smp.fractal;

//import edu.rit.pj.Comm;
import edu.rit.pj.IntegerForLoop;
import edu.rit.pj.ParallelRegion;
import edu.rit.pj.ParallelTeam;

import edu.rit.pj.reduction.IntegerOp;
import edu.rit.pj.reduction.SharedIntegerArray;

import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.io.PrintWriter;

/**
 * Class MSHistogramSmp2 is an SMP parallel program that calculates a histogram
 * of the Mandelbrot Set.
 * <P>
 * Usage: java -Dpj.nt=<I>K</I> edu.rit.smp.fractal.MSHistogramSmp2 <I>width</I>
 * <I>height</I> <I>xcenter</I> <I>ycenter</I> <I>resolution</I> <I>maxiter</I>
 * <I>outfile</I>
 * <BR><I>K</I> = Number of parallel threads
 * <BR><I>width</I> = Image width (pixels)
 * <BR><I>height</I> = Image height (pixels)
 * <BR><I>xcenter</I> = X coordinate of center point
 * <BR><I>ycenter</I> = Y coordinate of center point
 * <BR><I>resolution</I> = Pixels per unit
 * <BR><I>maxiter</I> = Maximum number of iterations
 * <BR><I>outfile</I> = Output file name
 * <P>
 * The program calculates an iteration count <I>i</I> for each pixel in the same
 * way as the {@linkplain MandelbrotSetSeq} program, with 0 &lt;= <I>i</I> &lt;=
 * <I>maxiter</I>. The program prints into the output file a histogram of the
 * <I>i</I> values; that is, for each value of <I>i</I>, how many times that
 * value occurred in the image.
 * <P>
 * The computation is performed in parallel in multiple threads. The program
 * uses the reduction pattern with a shared reduction variable to accumulate the
 * histogram. The program measures the computation's running time, including the
 * time to print the output.
 *
 * @author  Alan Kaminsky
 * @version 02-Feb-2008
 */
public class MSHistogramSmp2
	{

// Prevent construction.

	private MSHistogramSmp2()
		{
		}

// Program shared variables.

	// Command line arguments.
	static int width;
	static int height;
	static double xcenter;
	static double ycenter;
	static double resolution;
	static int maxiter;
	static File outfile;

	// Initial pixel offsets from center.
	static int xoffset;
	static int yoffset;

	// Histogram (array of counters indexed by pixel value).
	static SharedIntegerArray histogram;

// Main program.

	/**
	 * Mandelbrot Set main program.
	 */
	public static void main
		(String[] args)
		throws Exception
		{
		//Comm.init (args);

		// Start timing.
		long t1 = System.currentTimeMillis();

		// Validate command line arguments.
		if (args.length != 7) usage();
		width = Integer.parseInt (args[0]);
		height = Integer.parseInt (args[1]);
		xcenter = Double.parseDouble (args[2]);
		ycenter = Double.parseDouble (args[3]);
		resolution = Double.parseDouble (args[4]);
		maxiter = Integer.parseInt (args[5]);
		outfile = new File (args[6]);

		// Initial pixel offsets from center.
		xoffset = -(width - 1) / 2;
		yoffset = (height - 1) / 2;

		// Create histogram.
		histogram = new SharedIntegerArray (maxiter + 1);

		long t2 = System.currentTimeMillis();

		// Parallel computation region.
		new ParallelTeam().execute (new ParallelRegion()
			{
			public void run() throws Exception
				{
				execute (0, height-1, new IntegerForLoop()
					{
					// Per-thread histogram, plus extra padding.
					int[] thr_histogram = new int [maxiter + 1 + 32];
					long p0, p1, p2, p3, p4, p5, p6, p7;
					long p8, p9, pa, pb, pc, pd, pe, pf;

					public void run (int first, int last)
						{
						// Compute all rows and columns.
						for (int r = first; r <= last; ++ r)
							{
							double y = ycenter + (yoffset - r) / resolution;

							for (int c = 0; c < width; ++ c)
								{
								double x = xcenter + (xoffset + c) / resolution;

								// Iterate until convergence.
								int i = 0;
								double aold = 0.0;
								double bold = 0.0;
								double a = 0.0;
								double b = 0.0;
								double zmagsqr = 0.0;
								while (i < maxiter && zmagsqr <= 4.0)
									{
									++ i;
									a = aold*aold - bold*bold + x;
									b = 2.0*aold*bold + y;
									zmagsqr = a*a + b*b;
									aold = a;
									bold = b;
									}

								// Increment histogram counter for pixel value.
								++ thr_histogram[i];
								}
							}
						}

					// Reduce per-thread histogram into global histogram.
					public void finish()
						{
						histogram.reduce (thr_histogram, IntegerOp.SUM);
						}
					});
				}
			});

		long t3 = System.currentTimeMillis();

		// Print histogram.
		PrintWriter out =
			new PrintWriter
				(new BufferedWriter
					(new FileWriter (outfile)));
		for (int i = 0; i <= maxiter; ++ i)
			{
			out.print (i);
			out.print ('\t');
			out.print (histogram.get(i));
			out.println();
			}
		out.close();

		// Stop timing.
		long t4 = System.currentTimeMillis();
		System.out.println ((t2-t1) + " msec pre");
		System.out.println ((t3-t2) + " msec calc");
		System.out.println ((t4-t3) + " msec post");
		System.out.println ((t4-t1) + " msec total");
		}

// Hidden operations.

	/**
	 * Print a usage message and exit.
	 */
	private static void usage()
		{
		System.err.println ("Usage: java -Dpj.nt=<K> edu.rit.smp.fractal.MSHistogramSmp2 <width> <height> <xcenter> <ycenter> <resolution> <maxiter> <outfile>");
		System.err.println ("<K> = Number of parallel threads");
		System.err.println ("<width> = Image width (pixels)");
		System.err.println ("<height> = Image height (pixels)");
		System.err.println ("<xcenter> = X coordinate of center point");
		System.err.println ("<ycenter> = Y coordinate of center point");
		System.err.println ("<resolution> = Pixels per unit");
		System.err.println ("<maxiter> = Maximum number of iterations");
		System.err.println ("<outfile> = Output file name");
		System.exit (1);
		}

	}
