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 static org.apache.commons.io.IOUtils.EOF;
020
021import java.io.EOFException;
022import java.io.IOException;
023import java.io.InputStream;
024import java.io.OutputStream;
025
026/**
027 * Utility code for dealing with different endian systems.
028 * <p>
029 * Different computer architectures adopt different conventions for
030 * byte ordering. In so-called "Little Endian" architectures (eg Intel),
031 * the low-order byte is stored in memory at the lowest address, and
032 * subsequent bytes at higher addresses. For "Big Endian" architectures
033 * (eg Motorola), the situation is reversed.
034 * This class helps you solve this incompatibility.
035 * <p>
036 * Origin of code: Excalibur
037 *
038 * @see org.apache.commons.io.input.SwappedDataInputStream
039 */
040public class EndianUtils {
041
042    /**
043     * Instances should NOT be constructed in standard programming.
044     */
045    public EndianUtils() {
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(final 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(final 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(final 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(final 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(final 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(final byte[] data, final int offset, final 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(final byte[] data, final 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(final byte[] data, final 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(final byte[] data, final int offset, final 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(final byte[] data, final 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(final byte[] data, final int offset) {
184        final long low = ( ( ( data[ offset + 0 ] & 0xff ) << 0 ) +
185                     ( ( data[ offset + 1 ] & 0xff ) << 8 ) +
186                     ( ( data[ offset + 2 ] & 0xff ) << 16 ) );
187
188        final 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(final byte[] data, final int offset, final 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(final byte[] data, final int offset) {
219        final long low = readSwappedInteger(data, offset);
220        final long high = readSwappedInteger(data, offset + 4);
221        return (high << 32) + (0xffffffffL & low);
222    }
223
224    /**
225     * Writes a "float" value to a byte array at a given offset. The value is
226     * converted to the opposed endian system while writing.
227     * @param data target byte array
228     * @param offset starting offset in the byte array
229     * @param value value to write
230     */
231    public static void writeSwappedFloat(final byte[] data, final int offset, final float value) {
232        writeSwappedInteger( data, offset, Float.floatToIntBits( value ) );
233    }
234
235    /**
236     * Reads a "float" value from a byte array at a given offset. The value is
237     * converted to the opposed endian system while reading.
238     * @param data source byte array
239     * @param offset starting offset in the byte array
240     * @return the value read
241     */
242    public static float readSwappedFloat(final byte[] data, final int offset) {
243        return Float.intBitsToFloat( readSwappedInteger( data, offset ) );
244    }
245
246    /**
247     * Writes a "double" value to a byte array at a given offset. The value is
248     * converted to the opposed endian system while writing.
249     * @param data target byte array
250     * @param offset starting offset in the byte array
251     * @param value value to write
252     */
253    public static void writeSwappedDouble(final byte[] data, final int offset, final double value) {
254        writeSwappedLong( data, offset, Double.doubleToLongBits( value ) );
255    }
256
257    /**
258     * Reads a "double" value from a byte array at a given offset. The value is
259     * converted to the opposed endian system while reading.
260     * @param data source byte array
261     * @param offset starting offset in the byte array
262     * @return the value read
263     */
264    public static double readSwappedDouble(final byte[] data, final int offset) {
265        return Double.longBitsToDouble( readSwappedLong( data, offset ) );
266    }
267
268    /**
269     * Writes a "short" value to an OutputStream. The value is
270     * converted to the opposed endian system while writing.
271     * @param output target OutputStream
272     * @param value value to write
273     * @throws IOException in case of an I/O problem
274     */
275    public static void writeSwappedShort(final OutputStream output, final short value) throws IOException {
276        output.write((byte) ((value >> 0) & 0xff));
277        output.write((byte) ((value >> 8) & 0xff));
278    }
279
280    /**
281     * Reads a "short" value from an InputStream. The value is
282     * converted to the opposed endian system while reading.
283     * @param input source InputStream
284     * @return the value just read
285     * @throws IOException in case of an I/O problem
286     */
287    public static short readSwappedShort(final InputStream input) throws IOException {
288        return (short) (((read(input) & 0xff) << 0) + ((read(input) & 0xff) << 8));
289    }
290
291    /**
292     * Reads a unsigned short (16-bit) from an InputStream. The value is
293     * converted to the opposed endian system while reading.
294     * @param input source InputStream
295     * @return the value just read
296     * @throws IOException in case of an I/O problem
297     */
298    public static int readSwappedUnsignedShort(final InputStream input) throws IOException {
299        final int value1 = read(input);
300        final int value2 = read(input);
301
302        return (((value1 & 0xff) << 0) + ((value2 & 0xff) << 8));
303    }
304
305    /**
306     * Writes a "int" value to an OutputStream. The value is converted to the opposed endian system while writing.
307     *
308     * @param output target OutputStream
309     * @param value value to write
310     * @throws IOException in case of an I/O problem
311     */
312    public static void writeSwappedInteger(final OutputStream output, final int value) throws IOException {
313        output.write((byte) ((value >> 0) & 0xff));
314        output.write((byte) ((value >> 8) & 0xff));
315        output.write((byte) ((value >> 16) & 0xff));
316        output.write((byte) ((value >> 24) & 0xff));
317    }
318
319    /**
320     * Reads a "int" value from an InputStream. The value is
321     * converted to the opposed endian system while reading.
322     * @param input source InputStream
323     * @return the value just read
324     * @throws IOException in case of an I/O problem
325     */
326    public static int readSwappedInteger(final InputStream input) throws IOException {
327        final int value1 = read(input);
328        final int value2 = read(input);
329        final int value3 = read(input);
330        final int value4 = read(input);
331
332        return ((value1 & 0xff) << 0) + ((value2 & 0xff) << 8) + ((value3 & 0xff) << 16) + ((value4 & 0xff) << 24);
333    }
334
335    /**
336     * Reads a unsigned integer (32-bit) from an InputStream. The value is
337     * converted to the opposed endian system while reading.
338     * @param input source InputStream
339     * @return the value just read
340     * @throws IOException in case of an I/O problem
341     */
342    public static long readSwappedUnsignedInteger(final InputStream input) throws IOException {
343        final int value1 = read(input);
344        final int value2 = read(input);
345        final int value3 = read(input);
346        final int value4 = read(input);
347
348        final long low = (((value1 & 0xff) << 0) + ((value2 & 0xff) << 8) + ((value3 & 0xff) << 16));
349
350        final long high = value4 & 0xff;
351
352        return (high << 24) + (0xffffffffL & low);
353    }
354
355    /**
356     * Writes a "long" value to an OutputStream. The value is
357     * converted to the opposed endian system while writing.
358     * @param output target OutputStream
359     * @param value value to write
360     * @throws IOException in case of an I/O problem
361     */
362    public static void writeSwappedLong(final OutputStream output, final long value) throws IOException {
363        output.write((byte) ((value >> 0) & 0xff));
364        output.write((byte) ((value >> 8) & 0xff));
365        output.write((byte) ((value >> 16) & 0xff));
366        output.write((byte) ((value >> 24) & 0xff));
367        output.write((byte) ((value >> 32) & 0xff));
368        output.write((byte) ((value >> 40) & 0xff));
369        output.write((byte) ((value >> 48) & 0xff));
370        output.write((byte) ((value >> 56) & 0xff));
371    }
372
373    /**
374     * Reads a "long" value from an InputStream. The value is
375     * converted to the opposed endian system while reading.
376     * @param input source InputStream
377     * @return the value just read
378     * @throws IOException in case of an I/O problem
379     */
380    public static long readSwappedLong(final InputStream input) throws IOException {
381        final byte[] bytes = new byte[8];
382        for (int i = 0; i < 8; i++) {
383            bytes[i] = (byte) read(input);
384        }
385        return readSwappedLong(bytes, 0);
386    }
387
388    /**
389     * Writes a "float" value to an OutputStream. The value is
390     * converted to the opposed endian system while writing.
391     * @param output target OutputStream
392     * @param value value to write
393     * @throws IOException in case of an I/O problem
394     */
395    public static void writeSwappedFloat(final OutputStream output, final float value) throws IOException {
396        writeSwappedInteger(output, Float.floatToIntBits(value));
397    }
398
399    /**
400     * Reads a "float" value from an InputStream. The value is
401     * converted to the opposed endian system while reading.
402     * @param input source InputStream
403     * @return the value just read
404     * @throws IOException in case of an I/O problem
405     */
406    public static float readSwappedFloat(final InputStream input) throws IOException {
407        return Float.intBitsToFloat(readSwappedInteger(input));
408    }
409
410    /**
411     * Writes a "double" value to an OutputStream. The value is
412     * converted to the opposed endian system while writing.
413     * @param output target OutputStream
414     * @param value value to write
415     * @throws IOException in case of an I/O problem
416     */
417    public static void writeSwappedDouble(final OutputStream output, final double value) throws IOException {
418        writeSwappedLong(output, Double.doubleToLongBits(value));
419    }
420
421    /**
422     * Reads a "double" value from an InputStream. The value is
423     * converted to the opposed endian system while reading.
424     * @param input source InputStream
425     * @return the value just read
426     * @throws IOException in case of an I/O problem
427     */
428    public static double readSwappedDouble(final InputStream input) throws IOException {
429        return Double.longBitsToDouble(readSwappedLong(input));
430    }
431
432    /**
433     * Reads the next byte from the input stream.
434     * @param input  the stream
435     * @return the byte
436     * @throws IOException if the end of file is reached
437     */
438    private static int read(final InputStream input) throws IOException {
439        final int value = input.read();
440
441        if (EOF == value) {
442            throw new EOFException("Unexpected EOF reached");
443        }
444
445        return value;
446    }
447}