Mega Code Archive
Utility code for dealing with different endian systems
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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.
*/
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;
}
}
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