/*
* 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
*
* @version $Id: EndianUtils.java 1302056 2012-03-18 03:03:38Z ggregory $
* @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;
}
}