org.apache.commons.io.EndianUtils Maven / Gradle / Ivy
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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 static org.apache.commons.io.IOUtils.EOF;
import java.io.EOFException;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
/**
* Utility code for dealing with different endian systems.
*
* 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 incompatibility.
*
* Origin of code: Excalibur
*
* @see org.apache.commons.io.input.SwappedDataInputStream
*/
public class EndianUtils {
/**
* Instances should NOT be constructed in standard programming.
*/
public EndianUtils() {
}
// ========================================== Swapping routines
/**
* Converts a "short" value between endian systems.
* @param value value to convert
* @return the converted value
*/
public static short swapShort(final 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(final 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(final 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(final 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(final 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(final byte[] data, final int offset, final 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(final byte[] data, final 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(final byte[] data, final 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(final byte[] data, final int offset, final 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(final byte[] data, final 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(final byte[] data, final int offset) {
final long low = ( ( ( data[ offset + 0 ] & 0xff ) << 0 ) +
( ( data[ offset + 1 ] & 0xff ) << 8 ) +
( ( data[ offset + 2 ] & 0xff ) << 16 ) );
final 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(final byte[] data, final int offset, final 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(final byte[] data, final int offset) {
final long low = readSwappedInteger(data, offset);
final long high = readSwappedInteger(data, offset + 4);
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(final byte[] data, final int offset, final 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(final byte[] data, final 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(final byte[] data, final int offset, final 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(final byte[] data, final 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(final OutputStream output, final 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(final 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(final InputStream input) throws IOException {
final int value1 = read(input);
final 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(final OutputStream output, final 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(final InputStream input) throws IOException {
final int value1 = read(input);
final int value2 = read(input);
final int value3 = read(input);
final 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(final InputStream input) throws IOException {
final int value1 = read(input);
final int value2 = read(input);
final int value3 = read(input);
final int value4 = read(input);
final long low = (((value1 & 0xff) << 0) + ((value2 & 0xff) << 8) + ((value3 & 0xff) << 16));
final 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(final OutputStream output, final 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(final InputStream input) throws IOException {
final 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(final OutputStream output, final 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(final 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(final OutputStream output, final 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(final 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(final InputStream input) throws IOException {
final int value = input.read();
if (EOF == value) {
throw new EOFException("Unexpected EOF reached");
}
return value;
}
}