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/* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.apache.commons.io; import java.io.EOFException; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; /** * Utility code for dealing with different endian systems. * <p> * Different computer architectures adopt different conventions for * byte ordering. In so-called "Little Endian" architectures (eg Intel), * the low-order byte is stored in memory at the lowest address, and * subsequent bytes at higher addresses. For "Big Endian" architectures * (eg Motorola), the situation is reversed. * This class helps you solve this incompatability. * <p> * Origin of code: Excalibur * * @author <a href="mailto:peter@apache.org">Peter Donald</a> * @version $Id: EndianUtils.java 539632 2007-05-18 23:37:59Z bayard $ * @see org.apache.commons.io.input.SwappedDataInputStream */ public class EndianUtils { /** * Instances should NOT be constructed in standard programming. */ public EndianUtils() { super(); } // ========================================== Swapping routines /** * Converts a "short" value between endian systems. * @param value value to convert * @return the converted value */ public static short swapShort(short value) { return (short) ((((value >> 0) & 0xff) << 8) + (((value >> 8) & 0xff) << 0)); } /** * Converts a "int" value between endian systems. * @param value value to convert * @return the converted value */ public static int swapInteger(int value) { return (((value >> 0) & 0xff) << 24) + (((value >> 8) & 0xff) << 16) + (((value >> 16) & 0xff) << 8) + (((value >> 24) & 0xff) << 0); } /** * Converts a "long" value between endian systems. * @param value value to convert * @return the converted value */ public static long swapLong(long value) { return (((value >> 0) & 0xff) << 56) + (((value >> 8) & 0xff) << 48) + (((value >> 16) & 0xff) << 40) + (((value >> 24) & 0xff) << 32) + (((value >> 32) & 0xff) << 24) + (((value >> 40) & 0xff) << 16) + (((value >> 48) & 0xff) << 8) + (((value >> 56) & 0xff) << 0); } /** * Converts a "float" value between endian systems. * @param value value to convert * @return the converted value */ public static float swapFloat(float value) { return Float.intBitsToFloat(swapInteger(Float.floatToIntBits(value))); } /** * Converts a "double" value between endian systems. * @param value value to convert * @return the converted value */ public static double swapDouble(double value) { return Double.longBitsToDouble(swapLong(Double.doubleToLongBits(value))); } // ========================================== Swapping read/write routines /** * Writes a "short" value to a byte array at a given offset. The value is * converted to the opposed endian system while writing. * @param data target byte array * @param offset starting offset in the byte array * @param value value to write */ public static void writeSwappedShort(byte[] data, int offset, short value) { data[offset + 0] = (byte) ((value >> 0) & 0xff); data[offset + 1] = (byte) ((value >> 8) & 0xff); } /** * Reads a "short" value from a byte array at a given offset. The value is * converted to the opposed endian system while reading. * @param data source byte array * @param offset starting offset in the byte array * @return the value read */ public static short readSwappedShort(byte[] data, int offset) { return (short) (((data[offset + 0] & 0xff) << 0) + ((data[offset + 1] & 0xff) << 8)); } /** * Reads an unsigned short (16-bit) value from a byte array at a given * offset. The value is converted to the opposed endian system while * reading. * @param data source byte array * @param offset starting offset in the byte array * @return the value read */ public static int readSwappedUnsignedShort(byte[] data, int offset) { return (((data[offset + 0] & 0xff) << 0) + ((data[offset + 1] & 0xff) << 8)); } /** * Writes a "int" value to a byte array at a given offset. The value is * converted to the opposed endian system while writing. * @param data target byte array * @param offset starting offset in the byte array * @param value value to write */ public static void writeSwappedInteger(byte[] data, int offset, int value) { data[offset + 0] = (byte) ((value >> 0) & 0xff); data[offset + 1] = (byte) ((value >> 8) & 0xff); data[offset + 2] = (byte) ((value >> 16) & 0xff); data[offset + 3] = (byte) ((value >> 24) & 0xff); } /** * Reads a "int" value from a byte array at a given offset. The value is * converted to the opposed endian system while reading. * @param data source byte array * @param offset starting offset in the byte array * @return the value read */ public static int readSwappedInteger(byte[] data, int offset) { return (((data[offset + 0] & 0xff) << 0) + ((data[offset + 1] & 0xff) << 8) + ((data[offset + 2] & 0xff) << 16) + ((data[offset + 3] & 0xff) << 24)); } /** * Reads an unsigned integer (32-bit) value from a byte array at a given * offset. The value is converted to the opposed endian system while * reading. * @param data source byte array * @param offset starting offset in the byte array * @return the value read */ public static long readSwappedUnsignedInteger(byte[] data, int offset) { long low = (((data[offset + 0] & 0xff) << 0) + ((data[offset + 1] & 0xff) << 8) + ((data[offset + 2] & 0xff) << 16)); long high = data[offset + 3] & 0xff; return (high << 24) + (0xffffffffL & low); } /** * Writes a "long" value to a byte array at a given offset. The value is * converted to the opposed endian system while writing. * @param data target byte array * @param offset starting offset in the byte array * @param value value to write */ public static void writeSwappedLong(byte[] data, int offset, long value) { data[offset + 0] = (byte) ((value >> 0) & 0xff); data[offset + 1] = (byte) ((value >> 8) & 0xff); data[offset + 2] = (byte) ((value >> 16) & 0xff); data[offset + 3] = (byte) ((value >> 24) & 0xff); data[offset + 4] = (byte) ((value >> 32) & 0xff); data[offset + 5] = (byte) ((value >> 40) & 0xff); data[offset + 6] = (byte) ((value >> 48) & 0xff); data[offset + 7] = (byte) ((value >> 56) & 0xff); } /** * Reads a "long" value from a byte array at a given offset. The value is * converted to the opposed endian system while reading. * @param data source byte array * @param offset starting offset in the byte array * @return the value read */ public static long readSwappedLong(byte[] data, int offset) { long low = ((data[offset + 0] & 0xff) << 0) + ((data[offset + 1] & 0xff) << 8) + ((data[offset + 2] & 0xff) << 16) + ((data[offset + 3] & 0xff) << 24); long high = ((data[offset + 4] & 0xff) << 0) + ((data[offset + 5] & 0xff) << 8) + ((data[offset + 6] & 0xff) << 16) + ((data[offset + 7] & 0xff) << 24); return (high << 32) + (0xffffffffL & low); } /** * Writes a "float" value to a byte array at a given offset. The value is * converted to the opposed endian system while writing. * @param data target byte array * @param offset starting offset in the byte array * @param value value to write */ public static void writeSwappedFloat(byte[] data, int offset, float value) { writeSwappedInteger(data, offset, Float.floatToIntBits(value)); } /** * Reads a "float" value from a byte array at a given offset. The value is * converted to the opposed endian system while reading. * @param data source byte array * @param offset starting offset in the byte array * @return the value read */ public static float readSwappedFloat(byte[] data, int offset) { return Float.intBitsToFloat(readSwappedInteger(data, offset)); } /** * Writes a "double" value to a byte array at a given offset. The value is * converted to the opposed endian system while writing. * @param data target byte array * @param offset starting offset in the byte array * @param value value to write */ public static void writeSwappedDouble(byte[] data, int offset, double value) { writeSwappedLong(data, offset, Double.doubleToLongBits(value)); } /** * Reads a "double" value from a byte array at a given offset. The value is * converted to the opposed endian system while reading. * @param data source byte array * @param offset starting offset in the byte array * @return the value read */ public static double readSwappedDouble(byte[] data, int offset) { return Double.longBitsToDouble(readSwappedLong(data, offset)); } /** * Writes a "short" value to an OutputStream. The value is * converted to the opposed endian system while writing. * @param output target OutputStream * @param value value to write * @throws IOException in case of an I/O problem */ public static void writeSwappedShort(OutputStream output, short value) throws IOException { output.write((byte) ((value >> 0) & 0xff)); output.write((byte) ((value >> 8) & 0xff)); } /** * Reads a "short" value from an InputStream. The value is * converted to the opposed endian system while reading. * @param input source InputStream * @return the value just read * @throws IOException in case of an I/O problem */ public static short readSwappedShort(InputStream input) throws IOException { return (short) (((read(input) & 0xff) << 0) + ((read(input) & 0xff) << 8)); } /** * Reads a unsigned short (16-bit) from an InputStream. The value is * converted to the opposed endian system while reading. * @param input source InputStream * @return the value just read * @throws IOException in case of an I/O problem */ public static int readSwappedUnsignedShort(InputStream input) throws IOException { int value1 = read(input); int value2 = read(input); return (((value1 & 0xff) << 0) + ((value2 & 0xff) << 8)); } /** * Writes a "int" value to an OutputStream. The value is * converted to the opposed endian system while writing. * @param output target OutputStream * @param value value to write * @throws IOException in case of an I/O problem */ public static void writeSwappedInteger(OutputStream output, int value) throws IOException { output.write((byte) ((value >> 0) & 0xff)); output.write((byte) ((value >> 8) & 0xff)); output.write((byte) ((value >> 16) & 0xff)); output.write((byte) ((value >> 24) & 0xff)); } /** * Reads a "int" value from an InputStream. The value is * converted to the opposed endian system while reading. * @param input source InputStream * @return the value just read * @throws IOException in case of an I/O problem */ public static int readSwappedInteger(InputStream input) throws IOException { int value1 = read(input); int value2 = read(input); int value3 = read(input); int value4 = read(input); return ((value1 & 0xff) << 0) + ((value2 & 0xff) << 8) + ((value3 & 0xff) << 16) + ((value4 & 0xff) << 24); } /** * Reads a unsigned integer (32-bit) from an InputStream. The value is * converted to the opposed endian system while reading. * @param input source InputStream * @return the value just read * @throws IOException in case of an I/O problem */ public static long readSwappedUnsignedInteger(InputStream input) throws IOException { int value1 = read(input); int value2 = read(input); int value3 = read(input); int value4 = read(input); long low = (((value1 & 0xff) << 0) + ((value2 & 0xff) << 8) + ((value3 & 0xff) << 16)); long high = value4 & 0xff; return (high << 24) + (0xffffffffL & low); } /** * Writes a "long" value to an OutputStream. The value is * converted to the opposed endian system while writing. * @param output target OutputStream * @param value value to write * @throws IOException in case of an I/O problem */ public static void writeSwappedLong(OutputStream output, long value) throws IOException { output.write((byte) ((value >> 0) & 0xff)); output.write((byte) ((value >> 8) & 0xff)); output.write((byte) ((value >> 16) & 0xff)); output.write((byte) ((value >> 24) & 0xff)); output.write((byte) ((value >> 32) & 0xff)); output.write((byte) ((value >> 40) & 0xff)); output.write((byte) ((value >> 48) & 0xff)); output.write((byte) ((value >> 56) & 0xff)); } /** * Reads a "long" value from an InputStream. The value is * converted to the opposed endian system while reading. * @param input source InputStream * @return the value just read * @throws IOException in case of an I/O problem */ public static long readSwappedLong(InputStream input) throws IOException { byte[] bytes = new byte[8]; for (int i = 0; i < 8; i++) { bytes[i] = (byte) read(input); } return readSwappedLong(bytes, 0); } /** * Writes a "float" value to an OutputStream. The value is * converted to the opposed endian system while writing. * @param output target OutputStream * @param value value to write * @throws IOException in case of an I/O problem */ public static void writeSwappedFloat(OutputStream output, float value) throws IOException { writeSwappedInteger(output, Float.floatToIntBits(value)); } /** * Reads a "float" value from an InputStream. The value is * converted to the opposed endian system while reading. * @param input source InputStream * @return the value just read * @throws IOException in case of an I/O problem */ public static float readSwappedFloat(InputStream input) throws IOException { return Float.intBitsToFloat(readSwappedInteger(input)); } /** * Writes a "double" value to an OutputStream. The value is * converted to the opposed endian system while writing. * @param output target OutputStream * @param value value to write * @throws IOException in case of an I/O problem */ public static void writeSwappedDouble(OutputStream output, double value) throws IOException { writeSwappedLong(output, Double.doubleToLongBits(value)); } /** * Reads a "double" value from an InputStream. The value is * converted to the opposed endian system while reading. * @param input source InputStream * @return the value just read * @throws IOException in case of an I/O problem */ public static double readSwappedDouble(InputStream input) throws IOException { return Double.longBitsToDouble(readSwappedLong(input)); } /** * Reads the next byte from the input stream. * @param input the stream * @return the byte * @throws IOException if the end of file is reached */ private static int read(InputStream input) throws IOException { int value = input.read(); if (-1 == value) { throw new EOFException("Unexpected EOF reached"); } return value; } }