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/*
* @(#)LEDataInputStream.java
*
* Summary: Little-Endian version of DataInputStream.
*
* Copyright: (c) 1998-2010 Roedy Green, Canadian Mind Products, http://mindprod.com
*
* Licence: This software may be copied and used freely for any purpose but military.
* http://mindprod.com/contact/nonmil.html
*
* Requires: JDK 1.1+
*
* Created with: IntelliJ IDEA IDE.
*
* Version History:
* 1.8 2007-05-24
*/
package com.mindprod.ledatastream;
import java.io.DataInput;
import java.io.DataInputStream;
import java.io.IOException;
import java.io.InputStream;
/**
* Little-Endian version of DataInputStream.
*
* Very similar to DataInputStream except it reads little-endian instead of
* big-endian binary data. We can't extend DataInputStream directly since it has
* only final methods, though DataInputStream itself is not final. This forces
* us implement LEDataInputStream with a DataInputStream object, and use wrapper
* methods.
*
* @author Roedy Green, Canadian Mind Products
* @version 1.8 2007-05-24
* @since 1998
*/
public final class LEDataInputStream implements DataInput {
// ------------------------------ CONSTANTS ------------------------------
/**
* undisplayed copyright notice.
*/
private static final String EMBEDDED_COPYRIGHT =
"copyright (c) 1999-2010 Roedy Green, Canadian Mind Products, http://mindprod.com";
// ------------------------------ FIELDS ------------------------------
/**
* to get at the big-Endian methods of a basic DataInputStream
*/
protected final DataInputStream dis;
/**
* to get at the a basic readBytes method.
*/
protected final InputStream is;
/**
* work array for buffering input.
*/
protected final byte[] work;
// -------------------------- PUBLIC STATIC METHODS
// --------------------------
/**
* constructor.
*
* @param in binary inputstream of little-endian data.
*/
public LEDataInputStream(InputStream in) {
this.is = in;
this.dis = new DataInputStream(in);
work = new byte[8];
}
// -------------------------- PUBLIC INSTANCE METHODS
// --------------------------
/**
* Note. This is a STATIC method!
*
* @param in stream to read UTF chars from (endian irrelevant)
* @return string from stream
* @throws IOException if read fails.
*/
public static String readUTF(DataInput in) throws IOException {
return DataInputStream.readUTF(in);
}
/**
* close.
*
* @throws IOException if close fails.
*/
public final void close() throws IOException {
dis.close();
}
/**
* Read bytes. Watch out, read may return fewer bytes than requested.
*
* @param ba where the bytes go.
* @param off offset in buffer, not offset in file.
* @param len count of bytes to read.
* @return how many bytes read.
* @throws IOException if read fails.
*/
public final int read(byte ba[], int off, int len) throws IOException {
// For efficiency, we avoid one layer of wrapper
return is.read(ba, off, len);
}
/**
* read only a one-byte boolean.
*
* @return true or false.
* @throws IOException if read fails.
* @see java.io.DataInput#readBoolean()
*/
@Override
public final boolean readBoolean() throws IOException {
return dis.readBoolean();
}
/**
* read byte.
*
* @return the byte read.
* @throws IOException if read fails.
* @see java.io.DataInput#readByte()
*/
@Override
public final byte readByte() throws IOException {
return dis.readByte();
}
/**
* Read on char. like DataInputStream.readChar except little endian.
*
* @return little endian 16-bit unicode char from the stream.
* @throws IOException if read fails.
*/
@Override
public final char readChar() throws IOException {
dis.readFully(work, 0, 2);
return (char) ((work[1] & 0xff) << 8 | (work[0] & 0xff));
}
/**
* Read a double. like DataInputStream.readDouble except little endian.
*
* @return little endian IEEE double from the datastream.
* @throws IOException ioexception
*/
@Override
public final double readDouble() throws IOException {
return Double.longBitsToDouble(readLong());
}
/**
* Read one float. Like DataInputStream.readFloat except little endian.
*
* @return little endian IEEE float from the datastream.
* @throws IOException if read fails.
*/
@Override
public final float readFloat() throws IOException {
return Float.intBitsToFloat(readInt());
}
/**
* Read bytes until the array is filled.
*
* @see java.io.DataInput#readFully(byte[])
*/
@Override
public final void readFully(byte ba[]) throws IOException {
dis.readFully(ba, 0, ba.length);
}
/**
* Read bytes until the count is satisfied.
*
* @throws IOException if read fails.
* @see java.io.DataInput#readFully(byte[], int, int)
*/
@Override
public final void readFully(byte ba[], int off, int len) throws IOException {
dis.readFully(ba, off, len);
}
/**
* Read an int, 32-bits. Like DataInputStream.readInt except little endian.
*
* @return little-endian binary int from the datastream
* @throws IOException if read fails.
*/
@Override
public final int readInt() throws IOException {
dis.readFully(work, 0, 4);
return (work[3]) << 24 | (work[2] & 0xff) << 16 | (work[1] & 0xff) << 8 | (work[0] & 0xff);
}
/**
* Read a line.
*
* @return a rough approximation of the 8-bit stream as a 16-bit unicode
* string
* @throws IOException ioexception
* @deprecated This method does not properly convert bytes to characters.
* Use a Reader instead with a little-endian encoding.
*/
@Deprecated
@Override
public final String readLine() throws IOException {
return dis.readLine();
}
/**
* read a long, 64-bits. Like DataInputStream.readLong except little endian.
*
* @return little-endian binary long from the datastream.
* @throws IOException ioexception
*/
@Override
public final long readLong() throws IOException {
dis.readFully(work, 0, 8);
return (long) (work[7]) << 56
|
/* long cast needed or shift done modulo 32 */
(long) (work[6] & 0xff) << 48
| (long) (work[5] & 0xff) << 40
| (long) (work[4] & 0xff) << 32
| (long) (work[3] & 0xff) << 24
| (long) (work[2] & 0xff) << 16
| (long) (work[1] & 0xff) << 8
| work[0] & 0xff;
}
/**
* Read short, 16-bits. Like DataInputStream.readShort except little endian.
*
* @return little endian binary short from stream.
* @throws IOException if read fails.
*/
@Override
public final short readShort() throws IOException {
dis.readFully(work, 0, 2);
return (short) ((work[1] & 0xff) << 8 | (work[0] & 0xff));
}
/**
* Read UTF counted string.
*
* @return String read.
*/
@Override
public final String readUTF() throws IOException {
return dis.readUTF();
}
/**
* Read an unsigned byte. Note: returns an int, even though says Byte
* (non-Javadoc)
*
* @throws IOException if read fails.
* @see java.io.DataInput#readUnsignedByte()
*/
@Override
public final int readUnsignedByte() throws IOException {
return dis.readUnsignedByte();
}
/**
* Read an unsigned short, 16 bits. Like DataInputStream.readUnsignedShort
* except little endian. Note, returns int even though it reads a short.
*
* @return little-endian int from the stream.
* @throws IOException if read fails.
*/
@Override
public final int readUnsignedShort() throws IOException {
dis.readFully(work, 0, 2);
return ((work[1] & 0xff) << 8 | (work[0] & 0xff));
}
/**
* Skip over bytes in the stream. See the general contract of the
* skipBytes method of DataInput.
*
* Bytes for this operation are read from the contained input stream.
*
* @param n the number of bytes to be skipped.
* @return the actual number of bytes skipped.
* @throws IOException if an I/O error occurs.
*/
@Override
public final int skipBytes(int n) throws IOException {
return dis.skipBytes(n);
}
}