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This is the parser library for the PDS4 planetary data standard.
There is a newer version: 2.8.4
// Copyright 2019, California Institute of Technology ("Caltech").
// U.S. Government sponsorship acknowledged.
//
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// * Redistributions of source code must retain the above copyright notice,
// this list of conditions and the following disclaimer.
// * Redistributions must reproduce the above copyright notice, this list of
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// materials provided with the distribution.
// * Neither the name of Caltech nor its operating division, the Jet Propulsion
// Laboratory, nor the names of its contributors may be used to endorse or
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package gov.nasa.pds.objectAccess.array;

import java.nio.ByteBuffer;

/**
 * Implements a data type adapter for 4-byte integers.
 */
public class IntegerAdapter implements DataTypeAdapter {

	private static final int BYTE_MASK = 0xFF;
	private int elementSize;
	private boolean isBigEndian;
	private boolean isUnsigned;

	/**
	 * Creates a new adapter for an integer of given size.
	 *
	 * @param elementSize the number of bytes in the integer
	 * @param isBigEndian true, if the data is big-endian, false if little-endian
	 * @param isUnsigned true, if the data is unsigned, false if signed
	 */
	public IntegerAdapter(int elementSize, boolean isBigEndian, boolean isUnsigned) {
		this.elementSize = elementSize;
		this.isBigEndian = isBigEndian;
		this.isUnsigned = isUnsigned;
	}

	@Override
	public int getInt(ByteBuffer buf) {
		long value = getValue(buf);
		if (value < Integer.MIN_VALUE || value > Integer.MAX_VALUE) {
			throw new IllegalArgumentException("Value out of range for int: " + Long.toString(value));
		}

		return (int) value;
	}

	@Override
	public long getLong(ByteBuffer buf) {
		return getValue(buf);
	}

	@Override
	public double getDouble(ByteBuffer buf) {
		return getValue(buf);
	}

	private long getValue(ByteBuffer buf) {
		byte[] b = new byte[elementSize];

		long value = 0;
		if (isBigEndian) {
			value = buf.get();
			if (isUnsigned) {
				value &= BYTE_MASK;
			}
			for (int i=1; i < b.length; ++i) {
				value = (value << 8) | (buf.get() & BYTE_MASK);
			}
		} else {
			for (int i=0; i < b.length; ++i) {
				int newByte = buf.get();
				if (i < b.length-1 || isUnsigned) {
					newByte &= BYTE_MASK;
				}
				value |= (((long) newByte) << (8 * i));
			}
		}

		return value;
	}

}