Signed8BitIntegerMatrixBuf

//******************************************************************************
//
// File:    Signed8BitIntegerMatrixBuf.java
// Package: edu.rit.mp.buf
// Unit:    Class edu.rit.mp.buf.Signed8BitIntegerMatrixBuf
//
// This Java source file is copyright (C) 2009 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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// 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.mp.buf;

import java.nio.ByteBuffer;

import edu.rit.mp.Buf;
import edu.rit.mp.Signed8BitIntegerBuf;
import edu.rit.pj.reduction.IntegerOp;
import edu.rit.pj.reduction.Op;
import edu.rit.util.Arrays;
import edu.rit.util.Range;

/**
 * Class Signed8BitIntegerMatrixBuf provides a buffer for a matrix of signed
 * 8-bit integer items sent or received using the Message Protocol (MP). The
 * matrix row and column strides may be 1 or greater than 1. While an instance
 * of class Signed8BitIntegerMatrixBuf may be constructed directly, normally you
 * will use a factory method in class {@linkplain
 * edu.rit.mp.Signed8BitIntegerBuf Signed8BitIntegerBuf}. See that class for
 * further information.
 *
 * @author Alan Kaminsky
 * @version 05-Apr-2009
 */
public class Signed8BitIntegerMatrixBuf
        extends Signed8BitIntegerBuf {

// Hidden data members.
    int[][] myMatrix;
    Range myRowRange;
    Range myColRange;
    int myLowerRow;
    int myRowCount;
    int myRowStride;
    int myLowerCol;
    int myColCount;
    int myColStride;

// Exported constructors.
    /**
     * Construct a new signed 8-bit integer matrix buffer. It is assumed that
     * the rows and columns of <code>theMatrix</code> are allocated and that each
     * row of <code>theMatrix</code> has the same number of columns.
     *
     * @param theMatrix Matrix.
     * @param theRowRange Range of rows to include.
     * @param theColRange Range of columns to include.
     */
    public Signed8BitIntegerMatrixBuf(int[][] theMatrix,
            Range theRowRange,
            Range theColRange) {
        super(theRowRange.length() * theColRange.length());
        myMatrix = theMatrix;
        myRowRange = theRowRange;
        myColRange = theColRange;
        myLowerRow = theRowRange.lb();
        myRowCount = theRowRange.length();
        myRowStride = theRowRange.stride();
        myLowerCol = theColRange.lb();
        myColCount = theColRange.length();
        myColStride = theColRange.stride();
    }

// Exported operations.
    /**
     * {@inheritDoc}
     *
     * Obtain the given item from this buffer.
     * <P>
     * The <code>get()</code> method must not block the calling thread; if it does,
     * all message I/O in MP will be blocked.
     */
    public int get(int i) {
        return myMatrix[i2r(i) * myRowStride + myLowerRow][i2c(i) * myColStride + myLowerCol];
    }

    /**
     * {@inheritDoc}
     *
     * Store the given item in this buffer.
     * <P>
     * The <code>put()</code> method must not block the calling thread; if it does,
     * all message I/O in MP will be blocked.
     */
    public void put(int i,
            int item) {
        myMatrix[i2r(i) * myRowStride + myLowerRow][i2c(i) * myColStride + myLowerCol] = item;
    }

    /**
     * {@inheritDoc}
     *
     * Copy items from the given buffer to this buffer. The number of items
     * copied is this buffer's length or <code>theSrc</code>'s length, whichever is
     * smaller. If <code>theSrc</code> is this buffer, the <code>copy()</code> method
     * does nothing.
     * @exception ClassCastException (unchecked exception) Thrown if
     * <code>theSrc</code>'s item data type is not the same as this buffer's item
     * data type.
     */
    public void copy(Buf theSrc) {
        if (theSrc == this) {
        } else if (theSrc instanceof Signed8BitIntegerMatrixBuf) {
            Signed8BitIntegerMatrixBuf src
                    = (Signed8BitIntegerMatrixBuf) theSrc;
            Arrays.copy(src.myMatrix, src.myRowRange, src.myColRange,
                    this.myMatrix, this.myRowRange, this.myColRange);
        } else {
            Signed8BitIntegerBuf.defaultCopy((Signed8BitIntegerBuf) theSrc, this);
        }
    }

    /**
     * {@inheritDoc}
     *
     * Create a buffer for performing parallel reduction using the given binary
     * operation. The results of the reduction are placed into this buffer.
     * @exception ClassCastException (unchecked exception) Thrown if this
     * buffer's element data type and the given binary operation's argument data
     * type are not the same.
     */
    public Buf getReductionBuf(Op op) {
        return new Signed8BitIntegerMatrixReductionBuf(myMatrix, myRowRange, myColRange, (IntegerOp) op);
    }

// Hidden operations.
    /**
     * {@inheritDoc}
     *
     * Send as many items as possible from this buffer to the given byte buffer.
     * <P>
     * The <code>sendItems()</code> method must not block the calling thread; if it
     * does, all message I/O in MP will be blocked.
     */
    protected int sendItems(int i,
            ByteBuffer buffer) {
        int n = 0;
        int r = i2r(i);
        int row = r * myRowStride + myLowerRow;
        int c = i2c(i);
        int col = c * myColStride + myLowerCol;
        int ncols = Math.min(myColCount - c, buffer.remaining());
        while (r < myRowCount && ncols > 0) {
            int[] myMatrix_row = myMatrix[row];
            while (c < ncols) {
                buffer.put((byte) myMatrix_row[col]);
                ++c;
                col += myColStride;
            }
            n += ncols;
            ++r;
            row += myRowStride;
            c = 0;
            col = myLowerCol;
            ncols = Math.min(myColCount, buffer.remaining());
        }
        return n;
    }

    /**
     * {@inheritDoc}
     *
     * Receive as many items as possible from the given byte buffer to this
     * buffer.
     * <P>
     * The <code>receiveItems()</code> method must not block the calling thread; if
     * it does, all message I/O in MP will be blocked.
     */
    protected int receiveItems(int i,
            int num,
            ByteBuffer buffer) {
        num = Math.min(num, buffer.remaining());
        int n = 0;
        int r = i2r(i);
        int row = r * myRowStride + myLowerRow;
        int c = i2c(i);
        int col = c * myColStride + myLowerCol;
        int ncols = Math.min(myColCount - c, num);
        while (r < myRowCount && ncols > 0) {
            int[] myMatrix_row = myMatrix[row];
            for (c = 0; c < ncols; ++c) {
                myMatrix_row[col] = buffer.get();
                col += myColStride;
            }
            num -= ncols;
            n += ncols;
            ++r;
            row += myRowStride;
            col = myLowerCol;
            ncols = Math.min(myColCount, num);
        }
        return n;
    }

    /**
     * Convert the given buffer index to a row index.
     */
    int i2r(int i) {
        return myColCount == 0 ? i : i / myColCount;
    }

    /**
     * Convert the given buffer index to a column index.
     */
    int i2c(int i) {
        return myColCount == 0 ? 0 : i % myColCount;
    }

}