Application: gvSIG desktop

/* gvSIG. Sistema de Informaci?n Geogr?fica de la Generalitat Valenciana

 *

 * Copyright (C) 2006 Prodevelop and Generalitat Valenciana.

 *

 * This program 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 2

 * of the License, or (at your option) any later version.

 *

 * This program 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.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307,USA.

 *

 * For more information, contact:

 *

 *   Generalitat Valenciana

 *   Conselleria d'Infraestructures i Transport

 *   Av. Blasco Ib??ez, 50

 *   46010 VALENCIA

 *   SPAIN

 *

 *   +34 963862235

 *   gvsig@gva.es

 *   http://www.gvsig.gva.es

 *

 *    or

 *

 *   Prodevelop Integraci?n de Tecnolog?as SL

 *   Conde Salvatierra de ?lava , 34-10

 *   46004 Valencia

 *   Spain

 *

 *   +34 963 510 612

 *   +34 963 510 968

 *   gis@prodevelop.es

 *   http://www.prodevelop.es

 *

 *    or

 *

 *   Instituto de Rob?tica

 *   Apartado de correos 2085

 *   46071 Valencia

 *   (Spain)

 *   

 *   +34 963 543 577

 *   jjordan@robotica.uv.es

 *   http://robotica.uv.es

 *   

 */

package org.gvsig.data.datastores.vectorial.file;

import java.nio.ByteOrder;

/**

 * This class replaces the byte buffer used in J2SE to store a file in memory.

 * 

 * @see java.nio.ByteOrder

 * 

 * @author jldominguez

 *

 */

public class FalseByteBuffer {

        private byte[] bytes;

        private ByteOrder byteOrder = ByteOrder.LITTLE_ENDIAN;

        private int pos = 0;

        /**

         * Constructor

         * @param bb array of bytes to be stored

         */

        public FalseByteBuffer(byte[] bb) {

                bytes = bb;

        }

        /**

         * Moves file cursor to position p 

         * @param p the new position

         */

        public void position(int p) {

                pos = p;

        }

        /**

         * 

         * @return current cursor position

         */

        public int getPosition() {

                return pos;

        }

        /**

         * @return byte pointed by cursor then increases cursor

         */

        public byte getByte() {

                byte resp = bytes[pos];

                pos++;

                return resp;

        }

        /**

         * Gets one byte

         * @param ind index of the byte of interest 

         * @return the byte of interest

         */

        public byte getByte(int ind) {

                return bytes[ind];

        }

        /**

         * @return integer pointed by cursor then increases cursor

         */

        public int getInt() {

                int resp = getInt(bytes, pos);

                pos = pos + 4;

                return resp;

        }

        /**

         * @return short pointed by cursor then increases cursor

         */

        public short getShort() {

                short resp = getShort(bytes, pos);

                pos = pos + 2;

                return resp;

        }

        /**

         * Gets the integer at a certain position

         * @param index the index of interest

         * @return the integer at a certain position

         */

        public int getInt(int index) {

                int resp = getInt(bytes, index);

                return resp;

        }

        /**

         * Gets some bytes.

         * @param out the array of bytes to be filled

         */

        public void getBytes(byte[] out) {

                for (int i=0; i<out.length; i++) {

                        out[i] = getByte(pos + i);

                }

                pos = pos + out.length;

        }

        /**

         * @return double pointed by cursor then increases cursor

         */

        public double getDouble() {

                double resp = getDouble(bytes, pos);

                pos = pos + 8;

                return resp;

        }

        private int getInt(final byte[] data, final int offset) {

        return (int) getNumber(data, offset, 4);

    }

        private short getShort(final byte[] data, final int offset) {

        return (short) getNumber(data, offset, 2);

    }

        private long getNumber(final byte[] data, final int offset, final int size) {

        long result = 0;

        if (byteOrder == ByteOrder.LITTLE_ENDIAN) {

            for (int j = offset + size - 1; j >= offset; j--) {

                result <<= 8;

                result |= 0xff & data[j];

            }

        } else {

            for (int j = offset; j <= offset + size - 1; j++) {

                result <<= 8;

                result |= 0xff & data[j];

            }

        }

        return result;

    }

        private double getDouble(final byte[] data, final int offset) {

        return Double.longBitsToDouble(getNumber(data, offset, 8));

    }

        /**

         * Sets byte order (big endian, little endian)

         * @param o byte order (big endian, little endian)

         */

        public void setByteOrder(ByteOrder o) {

                byteOrder = o;

        }

}