Source code

001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 * 
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 * 
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.io;
018
019import java.io.EOFException;
020import java.io.IOException;
021import java.io.InputStream;
022import java.io.OutputStream;
023
024/**
025 * Utility code for dealing with different endian systems.
026 * <p>
027 * Different computer architectures adopt different conventions for
028 * byte ordering. In so-called "Little Endian" architectures (eg Intel),
029 * the low-order byte is stored in memory at the lowest address, and
030 * subsequent bytes at higher addresses. For "Big Endian" architectures
031 * (eg Motorola), the situation is reversed.
032 * This class helps you solve this incompatability.
033 * <p>
034 * Origin of code: Excalibur
035 *
036 * @version $Id: EndianUtils.java 1302056 2012-03-18 03:03:38Z ggregory $
037 * @see org.apache.commons.io.input.SwappedDataInputStream
038 */
039public class EndianUtils {
040
041    /**
042     * Instances should NOT be constructed in standard programming.
043     */
044    public EndianUtils() {
045        super();
046    }
047
048    // ========================================== Swapping routines
049
050    /**
051     * Converts a "short" value between endian systems.
052     * @param value value to convert
053     * @return the converted value
054     */
055    public static short swapShort(short value) {
056        return (short) ( ( ( ( value >> 0 ) & 0xff ) << 8 ) +
057            ( ( ( value >> 8 ) & 0xff ) << 0 ) );
058    }
059
060    /**
061     * Converts a "int" value between endian systems.
062     * @param value value to convert
063     * @return the converted value
064     */
065    public static int swapInteger(int value) {
066        return
067            ( ( ( value >> 0 ) & 0xff ) << 24 ) +
068            ( ( ( value >> 8 ) & 0xff ) << 16 ) +
069            ( ( ( value >> 16 ) & 0xff ) << 8 ) +
070            ( ( ( value >> 24 ) & 0xff ) << 0 );
071    }
072
073    /**
074     * Converts a "long" value between endian systems.
075     * @param value value to convert
076     * @return the converted value
077     */
078    public static long swapLong(long value) {
079        return
080            ( ( ( value >> 0 ) & 0xff ) << 56 ) +
081            ( ( ( value >> 8 ) & 0xff ) << 48 ) +
082            ( ( ( value >> 16 ) & 0xff ) << 40 ) +
083            ( ( ( value >> 24 ) & 0xff ) << 32 ) +
084            ( ( ( value >> 32 ) & 0xff ) << 24 ) +
085            ( ( ( value >> 40 ) & 0xff ) << 16 ) +
086            ( ( ( value >> 48 ) & 0xff ) << 8 ) +
087            ( ( ( value >> 56 ) & 0xff ) << 0 );
088    }
089
090    /**
091     * Converts a "float" value between endian systems.
092     * @param value value to convert
093     * @return the converted value
094     */
095    public static float swapFloat(float value) {
096        return Float.intBitsToFloat( swapInteger( Float.floatToIntBits( value ) ) );
097    }
098
099    /**
100     * Converts a "double" value between endian systems.
101     * @param value value to convert
102     * @return the converted value
103     */
104    public static double swapDouble(double value) {
105        return Double.longBitsToDouble( swapLong( Double.doubleToLongBits( value ) ) );
106    }
107
108    // ========================================== Swapping read/write routines
109
110    /**
111     * Writes a "short" value to a byte array at a given offset. The value is
112     * converted to the opposed endian system while writing.
113     * @param data target byte array
114     * @param offset starting offset in the byte array
115     * @param value value to write
116     */
117    public static void writeSwappedShort(byte[] data, int offset, short value) {
118        data[ offset + 0 ] = (byte)( ( value >> 0 ) & 0xff );
119        data[ offset + 1 ] = (byte)( ( value >> 8 ) & 0xff );
120    }
121
122    /**
123     * Reads a "short" value from a byte array at a given offset. The value is
124     * converted to the opposed endian system while reading.
125     * @param data source byte array
126     * @param offset starting offset in the byte array
127     * @return the value read
128     */
129    public static short readSwappedShort(byte[] data, int offset) {
130        return (short)( ( ( data[ offset + 0 ] & 0xff ) << 0 ) +
131            ( ( data[ offset + 1 ] & 0xff ) << 8 ) );
132    }
133
134    /**
135     * Reads an unsigned short (16-bit) value from a byte array at a given
136     * offset. The value is converted to the opposed endian system while
137     * reading.
138     * @param data source byte array
139     * @param offset starting offset in the byte array
140     * @return the value read
141     */
142    public static int readSwappedUnsignedShort(byte[] data, int offset) {
143        return ( ( ( data[ offset + 0 ] & 0xff ) << 0 ) +
144            ( ( data[ offset + 1 ] & 0xff ) << 8 ) );
145    }
146
147    /**
148     * Writes a "int" value to a byte array at a given offset. The value is
149     * converted to the opposed endian system while writing.
150     * @param data target byte array
151     * @param offset starting offset in the byte array
152     * @param value value to write
153     */
154    public static void writeSwappedInteger(byte[] data, int offset, int value) {
155        data[ offset + 0 ] = (byte)( ( value >> 0 ) & 0xff );
156        data[ offset + 1 ] = (byte)( ( value >> 8 ) & 0xff );
157        data[ offset + 2 ] = (byte)( ( value >> 16 ) & 0xff );
158        data[ offset + 3 ] = (byte)( ( value >> 24 ) & 0xff );
159    }
160
161    /**
162     * Reads a "int" value from a byte array at a given offset. The value is
163     * converted to the opposed endian system while reading.
164     * @param data source byte array
165     * @param offset starting offset in the byte array
166     * @return the value read
167     */
168    public static int readSwappedInteger(byte[] data, int offset) {
169        return ( ( ( data[ offset + 0 ] & 0xff ) << 0 ) +
170            ( ( data[ offset + 1 ] & 0xff ) << 8 ) +
171            ( ( data[ offset + 2 ] & 0xff ) << 16 ) +
172            ( ( data[ offset + 3 ] & 0xff ) << 24 ) );
173    }
174
175    /**
176     * Reads an unsigned integer (32-bit) value from a byte array at a given
177     * offset. The value is converted to the opposed endian system while
178     * reading.
179     * @param data source byte array
180     * @param offset starting offset in the byte array
181     * @return the value read
182     */
183    public static long readSwappedUnsignedInteger(byte[] data, int offset) {
184        long low = ( ( ( data[ offset + 0 ] & 0xff ) << 0 ) +
185                     ( ( data[ offset + 1 ] & 0xff ) << 8 ) +
186                     ( ( data[ offset + 2 ] & 0xff ) << 16 ) );
187
188        long high = data[ offset + 3 ] & 0xff;
189
190        return (high << 24) + (0xffffffffL & low); 
191    }
192
193    /**
194     * Writes a "long" value to a byte array at a given offset. The value is
195     * converted to the opposed endian system while writing.
196     * @param data target byte array
197     * @param offset starting offset in the byte array
198     * @param value value to write
199     */
200    public static void writeSwappedLong(byte[] data, int offset, long value) {
201        data[ offset + 0 ] = (byte)( ( value >> 0 ) & 0xff );
202        data[ offset + 1 ] = (byte)( ( value >> 8 ) & 0xff );
203        data[ offset + 2 ] = (byte)( ( value >> 16 ) & 0xff );
204        data[ offset + 3 ] = (byte)( ( value >> 24 ) & 0xff );
205        data[ offset + 4 ] = (byte)( ( value >> 32 ) & 0xff );
206        data[ offset + 5 ] = (byte)( ( value >> 40 ) & 0xff );
207        data[ offset + 6 ] = (byte)( ( value >> 48 ) & 0xff );
208        data[ offset + 7 ] = (byte)( ( value >> 56 ) & 0xff );
209    }
210
211    /**
212     * Reads a "long" value from a byte array at a given offset. The value is
213     * converted to the opposed endian system while reading.
214     * @param data source byte array
215     * @param offset starting offset in the byte array
216     * @return the value read
217     */
218    public static long readSwappedLong(byte[] data, int offset) {
219        long low = 
220            ( ( data[ offset + 0 ] & 0xff ) << 0 ) +
221            ( ( data[ offset + 1 ] & 0xff ) << 8 ) +
222            ( ( data[ offset + 2 ] & 0xff ) << 16 ) +
223            ( ( data[ offset + 3 ] & 0xff ) << 24 );
224        long high = 
225            ( ( data[ offset + 4 ] & 0xff ) << 0 ) +
226            ( ( data[ offset + 5 ] & 0xff ) << 8 ) +
227            ( ( data[ offset + 6 ] & 0xff ) << 16 ) +
228            ( ( data[ offset + 7 ] & 0xff ) << 24 );
229        return (high << 32) + (0xffffffffL & low); 
230    }
231
232    /**
233     * Writes a "float" value to a byte array at a given offset. The value is
234     * converted to the opposed endian system while writing.
235     * @param data target byte array
236     * @param offset starting offset in the byte array
237     * @param value value to write
238     */
239    public static void writeSwappedFloat(byte[] data, int offset, float value) {
240        writeSwappedInteger( data, offset, Float.floatToIntBits( value ) );
241    }
242
243    /**
244     * Reads a "float" value from a byte array at a given offset. The value is
245     * converted to the opposed endian system while reading.
246     * @param data source byte array
247     * @param offset starting offset in the byte array
248     * @return the value read
249     */
250    public static float readSwappedFloat(byte[] data, int offset) {
251        return Float.intBitsToFloat( readSwappedInteger( data, offset ) );
252    }
253
254    /**
255     * Writes a "double" value to a byte array at a given offset. The value is
256     * converted to the opposed endian system while writing.
257     * @param data target byte array
258     * @param offset starting offset in the byte array
259     * @param value value to write
260     */
261    public static void writeSwappedDouble(byte[] data, int offset, double value) {
262        writeSwappedLong( data, offset, Double.doubleToLongBits( value ) );
263    }
264
265    /**
266     * Reads a "double" value from a byte array at a given offset. The value is
267     * converted to the opposed endian system while reading.
268     * @param data source byte array
269     * @param offset starting offset in the byte array
270     * @return the value read
271     */
272    public static double readSwappedDouble(byte[] data, int offset) {
273        return Double.longBitsToDouble( readSwappedLong( data, offset ) );
274    }
275
276    /**
277     * Writes a "short" value to an OutputStream. The value is
278     * converted to the opposed endian system while writing.
279     * @param output target OutputStream
280     * @param value value to write
281     * @throws IOException in case of an I/O problem
282     */
283    public static void writeSwappedShort(OutputStream output, short value)
284        throws IOException
285    {
286        output.write( (byte)( ( value >> 0 ) & 0xff ) );
287        output.write( (byte)( ( value >> 8 ) & 0xff ) );
288    }
289
290    /**
291     * Reads a "short" value from an InputStream. The value is
292     * converted to the opposed endian system while reading.
293     * @param input source InputStream
294     * @return the value just read
295     * @throws IOException in case of an I/O problem
296     */
297    public static short readSwappedShort(InputStream input)
298        throws IOException
299    {
300        return (short)( ( ( read( input ) & 0xff ) << 0 ) +
301            ( ( read( input ) & 0xff ) << 8 ) );
302    }
303
304    /**
305     * Reads a unsigned short (16-bit) from an InputStream. The value is
306     * converted to the opposed endian system while reading.
307     * @param input source InputStream
308     * @return the value just read
309     * @throws IOException in case of an I/O problem
310     */
311    public static int readSwappedUnsignedShort(InputStream input)
312        throws IOException
313    {
314        int value1 = read( input );
315        int value2 = read( input );
316
317        return ( ( ( value1 & 0xff ) << 0 ) +
318            ( ( value2 & 0xff ) << 8 ) );
319    }
320
321    /**
322     * Writes a "int" value to an OutputStream. The value is
323     * converted to the opposed endian system while writing.
324     * @param output target OutputStream
325     * @param value value to write
326     * @throws IOException in case of an I/O problem
327     */
328    public static void writeSwappedInteger(OutputStream output, int value)
329        throws IOException
330    {
331        output.write( (byte)( ( value >> 0 ) & 0xff ) );
332        output.write( (byte)( ( value >> 8 ) & 0xff ) );
333        output.write( (byte)( ( value >> 16 ) & 0xff ) );
334        output.write( (byte)( ( value >> 24 ) & 0xff ) );
335    }
336
337    /**
338     * Reads a "int" value from an InputStream. The value is
339     * converted to the opposed endian system while reading.
340     * @param input source InputStream
341     * @return the value just read
342     * @throws IOException in case of an I/O problem
343     */
344    public static int readSwappedInteger(InputStream input)
345        throws IOException
346    {
347        int value1 = read( input );
348        int value2 = read( input );
349        int value3 = read( input );
350        int value4 = read( input );
351
352        return ( ( value1 & 0xff ) << 0 ) +
353            ( ( value2 & 0xff ) << 8 ) +
354            ( ( value3 & 0xff ) << 16 ) +
355            ( ( value4 & 0xff ) << 24 );
356    }
357
358    /**
359     * Reads a unsigned integer (32-bit) from an InputStream. The value is
360     * converted to the opposed endian system while reading.
361     * @param input source InputStream
362     * @return the value just read
363     * @throws IOException in case of an I/O problem
364     */
365    public static long readSwappedUnsignedInteger(InputStream input)
366        throws IOException
367    {
368        int value1 = read( input );
369        int value2 = read( input );
370        int value3 = read( input );
371        int value4 = read( input );
372
373        long low = ( ( ( value1 & 0xff ) << 0 ) +
374                     ( ( value2 & 0xff ) << 8 ) +
375                     ( ( value3 & 0xff ) << 16 ) );
376
377        long high = value4 & 0xff;
378
379        return (high << 24) + (0xffffffffL & low); 
380    }
381
382    /**
383     * Writes a "long" value to an OutputStream. The value is
384     * converted to the opposed endian system while writing.
385     * @param output target OutputStream
386     * @param value value to write
387     * @throws IOException in case of an I/O problem
388     */
389    public static void writeSwappedLong(OutputStream output, long value)
390        throws IOException
391    {
392        output.write( (byte)( ( value >> 0 ) & 0xff ) );
393        output.write( (byte)( ( value >> 8 ) & 0xff ) );
394        output.write( (byte)( ( value >> 16 ) & 0xff ) );
395        output.write( (byte)( ( value >> 24 ) & 0xff ) );
396        output.write( (byte)( ( value >> 32 ) & 0xff ) );
397        output.write( (byte)( ( value >> 40 ) & 0xff ) );
398        output.write( (byte)( ( value >> 48 ) & 0xff ) );
399        output.write( (byte)( ( value >> 56 ) & 0xff ) );
400    }
401
402    /**
403     * Reads a "long" value from an InputStream. The value is
404     * converted to the opposed endian system while reading.
405     * @param input source InputStream
406     * @return the value just read
407     * @throws IOException in case of an I/O problem
408     */
409    public static long readSwappedLong(InputStream input)
410        throws IOException
411    {
412        byte[] bytes = new byte[8];
413        for ( int i=0; i<8; i++ ) {
414            bytes[i] = (byte) read( input );
415        }
416        return readSwappedLong( bytes, 0 );
417    }
418
419    /**
420     * Writes a "float" value to an OutputStream. The value is
421     * converted to the opposed endian system while writing.
422     * @param output target OutputStream
423     * @param value value to write
424     * @throws IOException in case of an I/O problem
425     */
426    public static void writeSwappedFloat(OutputStream output, float value)
427        throws IOException
428    {
429        writeSwappedInteger( output, Float.floatToIntBits( value ) );
430    }
431
432    /**
433     * Reads a "float" value from an InputStream. The value is
434     * converted to the opposed endian system while reading.
435     * @param input source InputStream
436     * @return the value just read
437     * @throws IOException in case of an I/O problem
438     */
439    public static float readSwappedFloat(InputStream input)
440        throws IOException
441    {
442        return Float.intBitsToFloat( readSwappedInteger( input ) );
443    }
444
445    /**
446     * Writes a "double" value to an OutputStream. The value is
447     * converted to the opposed endian system while writing.
448     * @param output target OutputStream
449     * @param value value to write
450     * @throws IOException in case of an I/O problem
451     */
452    public static void writeSwappedDouble(OutputStream output, double value)
453        throws IOException
454    {
455        writeSwappedLong( output, Double.doubleToLongBits( value ) );
456    }
457
458    /**
459     * Reads a "double" value from an InputStream. The value is
460     * converted to the opposed endian system while reading.
461     * @param input source InputStream
462     * @return the value just read
463     * @throws IOException in case of an I/O problem
464     */
465    public static double readSwappedDouble(InputStream input)
466        throws IOException
467    {
468        return Double.longBitsToDouble( readSwappedLong( input ) );
469    }
470
471    /**
472     * Reads the next byte from the input stream.
473     * @param input  the stream
474     * @return the byte
475     * @throws IOException if the end of file is reached
476     */
477    private static int read(InputStream input)
478        throws IOException
479    {
480        int value = input.read();
481
482        if( -1 == value ) {
483            throw new EOFException( "Unexpected EOF reached" );
484        }
485
486        return value;
487    }
488}