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PostGIS adds support for geographic objects to the PostgreSQL object-relational database.
There is a newer version: 2023.1.0
/*
 * ValueGetter.java
 * 
 * PostGIS extension for PostgreSQL JDBC driver - Binary Parser
 * 
 * (C) 2005 Markus Schaber, [email protected]
 *
 * (C) 2015 Phillip Ross, [email protected]
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 * 
 */

package org.postgis.binary;

public abstract class ValueGetter {
    ByteGetter data;
    int position;
    public final byte endian;

    public ValueGetter(ByteGetter data, byte endian) {
        this.data = data;
        this.endian = endian;
    }

    /**
     * Get a byte, should be equal for all endians
     *
     * @return the byte value
     */
    public byte getByte() {
        return (byte) data.get(position++);
    }

    public int getInt() {
        int res = getInt(position);
        position += 4;
        return res;
    }

    public long getLong() {
        long res = getLong(position);
        position += 8;
        return res;
    }

    /**
     * Get a 32-Bit integer
     *
     * @param index the index to get the value from
     * @return the int value
     */
    protected abstract int getInt(int index);

    /**
     * Get a long value. This is not needed directly, but as a nice side-effect
     * from GetDouble.
     *
     * @param index the index to get the value from
     * @return the long value
     */
    protected abstract long getLong(int index);

    /**
     * Get a double.
     *
     * @return the double value
     */
    public double getDouble() {
        long bitrep = getLong();
        return Double.longBitsToDouble(bitrep);
    }

    public static class XDR extends ValueGetter {
        public static final byte NUMBER = 0;

        public XDR(ByteGetter data) {
            super(data, NUMBER);
        }

        protected int getInt(int index) {
            return (data.get(index) << 24) + (data.get(index + 1) << 16)
                    + (data.get(index + 2) << 8) + data.get(index + 3);
        }

        protected long getLong(int index) {
            return ((long) data.get(index) << 56) + ((long) data.get(index + 1) << 48)
                    + ((long) data.get(index + 2) << 40) + ((long) data.get(index + 3) << 32)
                    + ((long) data.get(index + 4) << 24) + ((long) data.get(index + 5) << 16)
                    + ((long) data.get(index + 6) << 8) + ((long) data.get(index + 7) << 0);
        }
    }

    public static class NDR extends ValueGetter {
        public static final byte NUMBER = 1;

        public NDR(ByteGetter data) {
            super(data, NUMBER);
        }

        protected int getInt(int index) {
            return (data.get(index + 3) << 24) + (data.get(index + 2) << 16)
                    + (data.get(index + 1) << 8) + data.get(index);
        }

        protected long getLong(int index) {
            return ((long) data.get(index + 7) << 56) + ((long) data.get(index + 6) << 48)
                    + ((long) data.get(index + 5) << 40) + ((long) data.get(index + 4) << 32)
                    + ((long) data.get(index + 3) << 24) + ((long) data.get(index + 2) << 16)
                    + ((long) data.get(index + 1) << 8) + ((long) data.get(index) << 0);
        }
    }
}