LittleEndianRandomAccessFile.java
/*
* Copyright (c) 2008, Harald Kuhr
* 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 in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* * Neither the name of the copyright holder nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package com.twelvemonkeys.io;
import java.io.*;
import java.nio.channels.FileChannel;
/**
* A replacement for {@link java.io.RandomAccessFile} that is capable of reading
* and writing data in little endian byte order.
* <p>
* <em>Warning:
* The {@code DataInput} and {@code DataOutput} interfaces
* specifies big endian byte order in their documentation.
* This means that this class is, strictly speaking, not a proper
* implementation. However, I don't see a reason for the these interfaces to
* specify the byte order of their underlying representations.
* </em>
* </p>
*
* @see com.twelvemonkeys.io.LittleEndianDataInputStream
* @see com.twelvemonkeys.io.LittleEndianDataOutputStream
* @see java.io.RandomAccessFile
* @see java.io.DataInput
* @see java.io.DataOutput
*
* @author Elliotte Rusty Harold
* @author <a href="mailto:harald.kuhr@gmail.no">Harald Kuhr</a>
* @author last modified by $Author: haku $
* @version $Id: //depot/branches/personal/haraldk/twelvemonkeys/release-2/twelvemonkeys-core/src/main/java/com/twelvemonkeys/io/LittleEndianRandomAccessFile.java#1 $
*/
public class LittleEndianRandomAccessFile implements DataInput, DataOutput {
private RandomAccessFile file;
public LittleEndianRandomAccessFile(final String pName, final String pMode) throws FileNotFoundException {
this(FileUtil.resolve(pName), pMode);
}
public LittleEndianRandomAccessFile(final File pFile, final String pMode) throws FileNotFoundException {
file = new RandomAccessFile(pFile, pMode);
}
public void close() throws IOException {
file.close();
}
public FileChannel getChannel() {
return file.getChannel();
}
public FileDescriptor getFD() throws IOException {
return file.getFD();
}
public long getFilePointer() throws IOException {
return file.getFilePointer();
}
public long length() throws IOException {
return file.length();
}
public int read() throws IOException {
return file.read();
}
public int read(final byte[] b) throws IOException {
return file.read(b);
}
public int read(final byte[] b, final int off, final int len) throws IOException {
return file.read(b, off, len);
}
public void readFully(final byte[] b) throws IOException {
file.readFully(b);
}
public void readFully(final byte[] b, final int off, final int len) throws IOException {
file.readFully(b, off, len);
}
public String readLine() throws IOException {
return file.readLine();
}
/**
* Reads a {@code boolean} from the underlying input stream by
* reading a single byte. If the byte is zero, false is returned.
* If the byte is positive, true is returned.
*
* @return the {@code boolean} value read.
* @throws EOFException if the end of the underlying input stream
* has been reached
* @throws IOException if the underlying stream throws an IOException.
*/
public boolean readBoolean() throws IOException {
int b = file.read();
if (b < 0) {
throw new EOFException();
}
return b != 0;
}
/**
* Reads a signed {@code byte} from the underlying input stream
* with value between -128 and 127
*
* @return the {@code byte} value read.
* @throws EOFException if the end of the underlying input stream
* has been reached
* @throws IOException if the underlying stream throws an IOException.
*/
public byte readByte() throws IOException {
int b = file.read();
if (b < 0) {
throw new EOFException();
}
return (byte) b;
}
/**
* Reads an unsigned {@code byte} from the underlying
* input stream with value between 0 and 255
*
* @return the {@code byte} value read.
* @throws EOFException if the end of the underlying input
* stream has been reached
* @throws IOException if the underlying stream throws an IOException.
*/
public int readUnsignedByte() throws IOException {
int b = file.read();
if (b < 0) {
throw new EOFException();
}
return b;
}
/**
* Reads a two byte signed {@code short} from the underlying
* input stream in little endian order, low byte first.
*
* @return the {@code short} read.
* @throws EOFException if the end of the underlying input stream
* has been reached
* @throws IOException if the underlying stream throws an IOException.
*/
public short readShort() throws IOException {
int byte1 = file.read();
int byte2 = file.read();
// only need to test last byte read
// if byte1 is -1 so is byte2
if (byte2 < 0) {
throw new EOFException();
}
return (short) (((byte2 << 24) >>> 16) + (byte1 << 24) >>> 24);
}
/**
* Reads a two byte unsigned {@code short} from the underlying
* input stream in little endian order, low byte first.
*
* @return the int value of the unsigned short read.
* @throws EOFException if the end of the underlying input stream
* has been reached
* @throws IOException if the underlying stream throws an IOException.
*/
public int readUnsignedShort() throws IOException {
int byte1 = file.read();
int byte2 = file.read();
if (byte2 < 0) {
throw new EOFException();
}
//return ((byte2 << 24) >> 16) + ((byte1 << 24) >> 24);
return (byte2 << 8) + byte1;
}
/**
* Reads a two byte Unicode {@code char} from the underlying
* input stream in little endian order, low byte first.
*
* @return the int value of the unsigned short read.
* @throws EOFException if the end of the underlying input stream
* has been reached
* @throws IOException if the underlying stream throws an IOException.
*/
public char readChar() throws IOException {
int byte1 = file.read();
int byte2 = file.read();
if (byte2 < 0) {
throw new EOFException();
}
return (char) (((byte2 << 24) >>> 16) + ((byte1 << 24) >>> 24));
}
/**
* Reads a four byte signed {@code int} from the underlying
* input stream in little endian order, low byte first.
*
* @return the {@code int} read.
* @throws EOFException if the end of the underlying input stream
* has been reached
* @throws IOException if the underlying stream throws an IOException.
*/
public int readInt() throws IOException {
int byte1 = file.read();
int byte2 = file.read();
int byte3 = file.read();
int byte4 = file.read();
if (byte4 < 0) {
throw new EOFException();
}
return (byte4 << 24) + ((byte3 << 24) >>> 8) + ((byte2 << 24) >>> 16) + ((byte1 << 24) >>> 24);
}
/**
* Reads an eight byte signed {@code int} from the underlying
* input stream in little endian order, low byte first.
*
* @return the {@code int} read.
* @throws EOFException if the end of the underlying input stream
* has been reached
* @throws IOException if the underlying stream throws an IOException.
*/
public long readLong() throws IOException {
long byte1 = file.read();
long byte2 = file.read();
long byte3 = file.read();
long byte4 = file.read();
long byte5 = file.read();
long byte6 = file.read();
long byte7 = file.read();
long byte8 = file.read();
if (byte8 < 0) {
throw new EOFException();
}
return (byte8 << 56) + ((byte7 << 56) >>> 8)
+ ((byte6 << 56) >>> 16) + ((byte5 << 56) >>> 24)
+ ((byte4 << 56) >>> 32) + ((byte3 << 56) >>> 40)
+ ((byte2 << 56) >>> 48) + ((byte1 << 56) >>> 56);
}
/**
* Reads a string of no more than 65,535 characters
* from the underlying input stream using UTF-8
* encoding. This method first reads a two byte short
* in <b>big</b> endian order as required by the
* UTF-8 specification. This gives the number of bytes in
* the UTF-8 encoded version of the string.
* Next this many bytes are read and decoded as UTF-8
* encoded characters.
*
* @return the decoded string
* @throws UTFDataFormatException if the string cannot be decoded
* @throws IOException if the underlying stream throws an IOException.
*/
public String readUTF() throws IOException {
int byte1 = file.read();
int byte2 = file.read();
if (byte2 < 0) {
throw new EOFException();
}
int numbytes = (byte1 << 8) + byte2;
char result[] = new char[numbytes];
int numread = 0;
int numchars = 0;
while (numread < numbytes) {
int c1 = readUnsignedByte();
int c2, c3;
// The first four bits of c1 determine how many bytes are in this char
int test = c1 >> 4;
if (test < 8) { // one byte
numread++;
result[numchars++] = (char) c1;
}
else if (test == 12 || test == 13) { // two bytes
numread += 2;
if (numread > numbytes) {
throw new UTFDataFormatException();
}
c2 = readUnsignedByte();
if ((c2 & 0xC0) != 0x80) {
throw new UTFDataFormatException();
}
result[numchars++] = (char) (((c1 & 0x1F) << 6) | (c2 & 0x3F));
}
else if (test == 14) { // three bytes
numread += 3;
if (numread > numbytes) {
throw new UTFDataFormatException();
}
c2 = readUnsignedByte();
c3 = readUnsignedByte();
if (((c2 & 0xC0) != 0x80) || ((c3 & 0xC0) != 0x80)) {
throw new UTFDataFormatException();
}
result[numchars++] = (char) (((c1 & 0x0F) << 12) | ((c2 & 0x3F) << 6) | (c3 & 0x3F));
}
else { // malformed
throw new UTFDataFormatException();
}
} // end while
return new String(result, 0, numchars);
}
/**
* @return the next eight bytes of this input stream, interpreted as a
* little endian {@code double}.
* @throws EOFException if end of stream occurs before eight bytes
* have been read.
* @throws IOException if an I/O error occurs.
*/
public final double readDouble() throws IOException {
return Double.longBitsToDouble(readLong());
}
/**
* @return the next four bytes of this input stream, interpreted as a
* little endian {@code int}.
* @throws EOFException if end of stream occurs before four bytes
* have been read.
* @throws IOException if an I/O error occurs.
*/
public final float readFloat() throws IOException {
return Float.intBitsToFloat(readInt());
}
/**
* Sets the file-pointer offset, measured from the beginning of this
* file, at which the next read or write occurs. The offset may be
* set beyond the end of the file. Setting the offset beyond the end
* of the file does not change the file length. The file length will
* change only by writing after the offset has been set beyond the end
* of the file.
*
* @param pos the offset position, measured in bytes from the
* beginning of the file, at which to set the file
* pointer.
* @exception IOException if {@code pos} is less than
* {@code 0} or if an I/O error occurs.
*/
public void seek(final long pos) throws IOException {
file.seek(pos);
}
public void setLength(final long newLength) throws IOException {
file.setLength(newLength);
}
public int skipBytes(final int n) throws IOException {
return file.skipBytes(n);
}
public void write(final byte[] b) throws IOException {
file.write(b);
}
public void write(final byte[] b, final int off, final int len) throws IOException {
file.write(b, off, len);
}
public void write(final int b) throws IOException {
file.write(b);
}
/**
* Writes a {@code boolean} to the underlying output stream as
* a single byte. If the argument is true, the byte value 1 is written.
* If the argument is false, the byte value {@code 0} in written.
*
* @param pBoolean the {@code boolean} value to be written.
* @throws IOException if the underlying stream throws an IOException.
*/
public void writeBoolean(boolean pBoolean) throws IOException {
if (pBoolean) {
write(1);
}
else {
write(0);
}
}
/**
* Writes out a {@code byte} to the underlying output stream
*
* @param pByte the {@code byte} value to be written.
* @throws IOException if the underlying stream throws an IOException.
*/
public void writeByte(int pByte) throws IOException {
file.write(pByte);
}
/**
* Writes a two byte {@code short} to the underlying output stream in
* little endian order, low byte first.
*
* @param pShort the {@code short} to be written.
* @throws IOException if the underlying stream throws an IOException.
*/
public void writeShort(int pShort) throws IOException {
file.write(pShort & 0xFF);
file.write((pShort >>> 8) & 0xFF);
}
/**
* Writes a two byte {@code char} to the underlying output stream
* in little endian order, low byte first.
*
* @param pChar the {@code char} value to be written.
* @throws IOException if the underlying stream throws an IOException.
*/
public void writeChar(int pChar) throws IOException {
file.write(pChar & 0xFF);
file.write((pChar >>> 8) & 0xFF);
}
/**
* Writes a four-byte {@code int} to the underlying output stream
* in little endian order, low byte first, high byte last
*
* @param pInt the {@code int} to be written.
* @throws IOException if the underlying stream throws an IOException.
*/
public void writeInt(int pInt) throws IOException {
file.write(pInt & 0xFF);
file.write((pInt >>> 8) & 0xFF);
file.write((pInt >>> 16) & 0xFF);
file.write((pInt >>> 24) & 0xFF);
}
/**
* Writes an eight-byte {@code long} to the underlying output stream
* in little endian order, low byte first, high byte last
*
* @param pLong the {@code long} to be written.
* @throws IOException if the underlying stream throws an IOException.
*/
public void writeLong(long pLong) throws IOException {
file.write((int) pLong & 0xFF);
file.write((int) (pLong >>> 8) & 0xFF);
file.write((int) (pLong >>> 16) & 0xFF);
file.write((int) (pLong >>> 24) & 0xFF);
file.write((int) (pLong >>> 32) & 0xFF);
file.write((int) (pLong >>> 40) & 0xFF);
file.write((int) (pLong >>> 48) & 0xFF);
file.write((int) (pLong >>> 56) & 0xFF);
}
/**
* Writes a 4 byte Java float to the underlying output stream in
* little endian order.
*
* @param f the {@code float} value to be written.
* @throws IOException if an I/O error occurs.
*/
public final void writeFloat(float f) throws IOException {
writeInt(Float.floatToIntBits(f));
}
/**
* Writes an 8 byte Java double to the underlying output stream in
* little endian order.
*
* @param d the {@code double} value to be written.
* @throws IOException if an I/O error occurs.
*/
public final void writeDouble(double d) throws IOException {
writeLong(Double.doubleToLongBits(d));
}
/**
* Writes a string to the underlying output stream as a sequence of
* bytes. Each character is written to the data output stream as
* if by the {@code writeByte()} method.
*
* @param pString the {@code String} value to be written.
* @throws IOException if the underlying stream throws an IOException.
* @see #writeByte(int)
* @see #file
*/
public void writeBytes(String pString) throws IOException {
int length = pString.length();
for (int i = 0; i < length; i++) {
file.write((byte) pString.charAt(i));
}
}
/**
* Writes a string to the underlying output stream as a sequence of
* characters. Each character is written to the data output stream as
* if by the {@code writeChar} method.
*
* @param pString a {@code String} value to be written.
* @throws IOException if the underlying stream throws an IOException.
* @see #writeChar(int)
* @see #file
*/
public void writeChars(String pString) throws IOException {
int length = pString.length();
for (int i = 0; i < length; i++) {
int c = pString.charAt(i);
file.write(c & 0xFF);
file.write((c >>> 8) & 0xFF);
}
}
/**
* Writes a string of no more than 65,535 characters
* to the underlying output stream using UTF-8
* encoding. This method first writes a two byte short
* in <b>big</b> endian order as required by the
* UTF-8 specification. This gives the number of bytes in the
* UTF-8 encoded version of the string, not the number of characters
* in the string. Next each character of the string is written
* using the UTF-8 encoding for the character.
*
* @param pString the string to be written.
* @throws UTFDataFormatException if the string is longer than
* 65,535 characters.
* @throws IOException if the underlying stream throws an IOException.
*/
public void writeUTF(String pString) throws IOException {
int numchars = pString.length();
int numbytes = 0;
for (int i = 0; i < numchars; i++) {
int c = pString.charAt(i);
if ((c >= 0x0001) && (c <= 0x007F)) {
numbytes++;
}
else if (c > 0x07FF) {
numbytes += 3;
}
else {
numbytes += 2;
}
}
if (numbytes > 65535) {
throw new UTFDataFormatException();
}
file.write((numbytes >>> 8) & 0xFF);
file.write(numbytes & 0xFF);
for (int i = 0; i < numchars; i++) {
int c = pString.charAt(i);
if ((c >= 0x0001) && (c <= 0x007F)) {
file.write(c);
}
else if (c > 0x07FF) {
file.write(0xE0 | ((c >> 12) & 0x0F));
file.write(0x80 | ((c >> 6) & 0x3F));
file.write(0x80 | (c & 0x3F));
}
else {
file.write(0xC0 | ((c >> 6) & 0x1F));
file.write(0x80 | (c & 0x3F));
}
}
}
}