001 /* ByteBuffer.java --
002 Copyright (C) 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
003
004 This file is part of GNU Classpath.
005
006 GNU Classpath is free software; you can redistribute it and/or modify
007 it under the terms of the GNU General Public License as published by
008 the Free Software Foundation; either version 2, or (at your option)
009 any later version.
010
011 GNU Classpath is distributed in the hope that it will be useful, but
012 WITHOUT ANY WARRANTY; without even the implied warranty of
013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
014 General Public License for more details.
015
016 You should have received a copy of the GNU General Public License
017 along with GNU Classpath; see the file COPYING. If not, write to the
018 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019 02110-1301 USA.
020
021 Linking this library statically or dynamically with other modules is
022 making a combined work based on this library. Thus, the terms and
023 conditions of the GNU General Public License cover the whole
024 combination.
025
026 As a special exception, the copyright holders of this library give you
027 permission to link this library with independent modules to produce an
028 executable, regardless of the license terms of these independent
029 modules, and to copy and distribute the resulting executable under
030 terms of your choice, provided that you also meet, for each linked
031 independent module, the terms and conditions of the license of that
032 module. An independent module is a module which is not derived from
033 or based on this library. If you modify this library, you may extend
034 this exception to your version of the library, but you are not
035 obligated to do so. If you do not wish to do so, delete this
036 exception statement from your version. */
037
038
039 package java.nio;
040
041 // GCJ LOCAL: Change gnu.classpath.Pointer to RawData
042 import gnu.gcj.RawData;
043 import gnu.classpath.Pointer;
044
045 /**
046 * @since 1.4
047 */
048 public abstract class ByteBuffer extends Buffer
049 implements Comparable<ByteBuffer>
050 {
051 ByteOrder endian = ByteOrder.BIG_ENDIAN;
052 final byte[] backing_buffer;
053 final int array_offset;
054
055 ByteBuffer (int capacity, int limit, int position, int mark,
056 RawData address, byte[] backing_buffer, int array_offset)
057 {
058 super (capacity, limit, position, mark, address);
059 this.backing_buffer = backing_buffer;
060 this.array_offset = array_offset;
061 }
062
063 /**
064 * Allocates a new direct byte buffer.
065 */
066 public static ByteBuffer allocateDirect (int capacity)
067 {
068 return DirectByteBufferImpl.allocate (capacity);
069 }
070
071 /**
072 * Allocates a new <code>ByteBuffer</code> object with a given capacity.
073 */
074 public static ByteBuffer allocate (int capacity)
075 {
076 return wrap(new byte[capacity], 0, capacity);
077 }
078
079 /**
080 * Wraps a <code>byte</code> array into a <code>ByteBuffer</code>
081 * object.
082 *
083 * @exception IndexOutOfBoundsException If the preconditions on the offset
084 * and length parameters do not hold
085 */
086 public static final ByteBuffer wrap (byte[] array, int offset, int length)
087 {
088 // FIXME: In GCJ and other implementations where arrays may not
089 // move we might consider, at least when offset==0:
090 // return new DirectByteBufferImpl(array,
091 // address_of_data(array) + offset,
092 // length, length, 0, false);
093 // This may be more efficient, mainly because we can then use the
094 // same logic for all ByteBuffers.
095
096 return new ByteBufferImpl (array, 0, array.length, offset + length, offset, -1, false);
097 }
098
099 /**
100 * Wraps a <code>byte</code> array into a <code>ByteBuffer</code>
101 * object.
102 */
103 public static final ByteBuffer wrap (byte[] array)
104 {
105 return wrap (array, 0, array.length);
106 }
107
108 /**
109 * This method transfers <code>byte</code>s from this buffer into the given
110 * destination array. Before the transfer, it checks if there are fewer than
111 * length <code>byte</code>s remaining in this buffer.
112 *
113 * @param dst The destination array
114 * @param offset The offset within the array of the first <code>byte</code>
115 * to be written; must be non-negative and no larger than dst.length.
116 * @param length The maximum number of bytes to be written to the given array;
117 * must be non-negative and no larger than dst.length - offset.
118 *
119 * @exception BufferUnderflowException If there are fewer than length
120 * <code>byte</code>s remaining in this buffer.
121 * @exception IndexOutOfBoundsException If the preconditions on the offset
122 * and length parameters do not hold.
123 */
124 public ByteBuffer get (byte[] dst, int offset, int length)
125 {
126 checkArraySize(dst.length, offset, length);
127 checkForUnderflow(length);
128
129 for (int i = offset; i < offset + length; i++)
130 {
131 dst [i] = get ();
132 }
133
134 return this;
135 }
136
137 /**
138 * This method transfers <code>byte</code>s from this buffer into the given
139 * destination array.
140 *
141 * @param dst The byte array to write into.
142 *
143 * @exception BufferUnderflowException If there are fewer than dst.length
144 * <code>byte</code>s remaining in this buffer.
145 */
146 public ByteBuffer get (byte[] dst)
147 {
148 return get (dst, 0, dst.length);
149 }
150
151 /**
152 * Writes the content of the the <code>ByteBUFFER</code> src
153 * into the buffer. Before the transfer, it checks if there is fewer than
154 * <code>src.remaining()</code> space remaining in this buffer.
155 *
156 * @param src The source data.
157 *
158 * @exception BufferOverflowException If there is insufficient space in this
159 * buffer for the remaining <code>byte</code>s in the source buffer.
160 * @exception IllegalArgumentException If the source buffer is this buffer.
161 * @exception ReadOnlyBufferException If this buffer is read-only.
162 */
163 public ByteBuffer put (ByteBuffer src)
164 {
165 if (src == this)
166 throw new IllegalArgumentException ();
167
168 checkForOverflow(src.remaining());
169
170 if (src.remaining () > 0)
171 {
172 byte[] toPut = new byte [src.remaining ()];
173 src.get (toPut);
174 put (toPut);
175 }
176
177 return this;
178 }
179
180 /**
181 * Writes the content of the the <code>byte array</code> src
182 * into the buffer. Before the transfer, it checks if there is fewer than
183 * length space remaining in this buffer.
184 *
185 * @param src The array to copy into the buffer.
186 * @param offset The offset within the array of the first byte to be read;
187 * must be non-negative and no larger than src.length.
188 * @param length The number of bytes to be read from the given array;
189 * must be non-negative and no larger than src.length - offset.
190 *
191 * @exception BufferOverflowException If there is insufficient space in this
192 * buffer for the remaining <code>byte</code>s in the source array.
193 * @exception IndexOutOfBoundsException If the preconditions on the offset
194 * and length parameters do not hold
195 * @exception ReadOnlyBufferException If this buffer is read-only.
196 */
197 public ByteBuffer put (byte[] src, int offset, int length)
198 {
199 checkArraySize(src.length, offset, length);
200 checkForOverflow(length);
201
202 for (int i = offset; i < offset + length; i++)
203 put (src [i]);
204
205 return this;
206 }
207
208 /**
209 * Writes the content of the the <code>byte array</code> src
210 * into the buffer.
211 *
212 * @param src The array to copy into the buffer.
213 *
214 * @exception BufferOverflowException If there is insufficient space in this
215 * buffer for the remaining <code>byte</code>s in the source array.
216 * @exception ReadOnlyBufferException If this buffer is read-only.
217 */
218 public final ByteBuffer put (byte[] src)
219 {
220 return put (src, 0, src.length);
221 }
222
223 /**
224 * Tells whether ot not this buffer is backed by an accessible
225 * <code>byte</code> array.
226 */
227 public final boolean hasArray ()
228 {
229 return (backing_buffer != null
230 && !isReadOnly ());
231 }
232
233 /**
234 * Returns the <code>byte</code> array that backs this buffer.
235 *
236 * @exception ReadOnlyBufferException If this buffer is read-only.
237 * @exception UnsupportedOperationException If this buffer is not backed
238 * by an accessible array.
239 */
240 public final byte[] array ()
241 {
242 if (backing_buffer == null)
243 throw new UnsupportedOperationException ();
244
245 checkIfReadOnly();
246
247 return backing_buffer;
248 }
249
250 /**
251 * Returns the offset within this buffer's backing array of the first element.
252 *
253 * @exception ReadOnlyBufferException If this buffer is read-only.
254 * @exception UnsupportedOperationException If this buffer is not backed
255 * by an accessible array.
256 */
257 public final int arrayOffset ()
258 {
259 if (backing_buffer == null)
260 throw new UnsupportedOperationException ();
261
262 checkIfReadOnly();
263
264 return array_offset;
265 }
266
267 /**
268 * Calculates a hash code for this buffer.
269 *
270 * This is done with <code>int</code> arithmetic,
271 * where ** represents exponentiation, by this formula:<br>
272 * <code>s[position()] + 31 + (s[position()+1] + 30)*31**1 + ... +
273 * (s[limit()-1]+30)*31**(limit()-1)</code>.
274 * Where s is the buffer data. Note that the hashcode is dependent
275 * on buffer content, and therefore is not useful if the buffer
276 * content may change.
277 *
278 * @return the hash code
279 */
280 public int hashCode ()
281 {
282 int hashCode = get(position()) + 31;
283 int multiplier = 1;
284 for (int i = position() + 1; i < limit(); ++i)
285 {
286 multiplier *= 31;
287 hashCode += (get(i) + 30)*multiplier;
288 }
289 return hashCode;
290 }
291
292 /**
293 * Checks if this buffer is equal to obj.
294 */
295 public boolean equals (Object obj)
296 {
297 if (obj instanceof ByteBuffer)
298 {
299 return compareTo ((ByteBuffer) obj) == 0;
300 }
301
302 return false;
303 }
304
305 /**
306 * Compares two <code>ByteBuffer</code> objects.
307 *
308 * @exception ClassCastException If obj is not an object derived from
309 * <code>ByteBuffer</code>.
310 */
311 public int compareTo (ByteBuffer other)
312 {
313 int num = Math.min(remaining(), other.remaining());
314 int pos_this = position();
315 int pos_other = other.position();
316
317 for (int count = 0; count < num; count++)
318 {
319 byte a = get(pos_this++);
320 byte b = other.get(pos_other++);
321
322 if (a == b)
323 continue;
324
325 if (a < b)
326 return -1;
327
328 return 1;
329 }
330
331 return remaining() - other.remaining();
332 }
333
334 /**
335 * Returns the byte order of this buffer.
336 */
337 public final ByteOrder order ()
338 {
339 return endian;
340 }
341
342 /**
343 * Modifies this buffer's byte order.
344 */
345 public final ByteBuffer order (ByteOrder endian)
346 {
347 this.endian = endian;
348 return this;
349 }
350
351 /**
352 * Reads the <code>byte</code> at this buffer's current position,
353 * and then increments the position.
354 *
355 * @exception BufferUnderflowException If there are no remaining
356 * <code>byte</code>s in this buffer.
357 */
358 public abstract byte get ();
359
360 /**
361 * Writes the <code>byte</code> at this buffer's current position,
362 * and then increments the position.
363 *
364 * @exception BufferOverflowException If there no remaining
365 * <code>byte</code>s in this buffer.
366 * @exception ReadOnlyBufferException If this buffer is read-only.
367 */
368 public abstract ByteBuffer put (byte b);
369
370 /**
371 * Absolute get method.
372 *
373 * @exception IndexOutOfBoundsException If index is negative or not smaller
374 * than the buffer's limit.
375 */
376 public abstract byte get (int index);
377
378 /**
379 * Absolute put method.
380 *
381 * @exception IndexOutOfBoundsException If index is negative or not smaller
382 * than the buffer's limit.
383 * @exception ReadOnlyBufferException If this buffer is read-only.
384 */
385 public abstract ByteBuffer put (int index, byte b);
386
387 /**
388 * Compacts this buffer.
389 *
390 * @exception ReadOnlyBufferException If this buffer is read-only.
391 */
392 public abstract ByteBuffer compact ();
393
394 void shiftDown (int dst_offset, int src_offset, int count)
395 {
396 for (int i = 0; i < count; i++)
397 put(dst_offset + i, get(src_offset + i));
398 }
399
400 /**
401 * Tells whether or not this buffer is direct.
402 */
403 public abstract boolean isDirect ();
404
405 /**
406 * Creates a new <code>ByteBuffer</code> whose content is a shared
407 * subsequence of this buffer's content.
408 */
409 public abstract ByteBuffer slice ();
410
411 /**
412 * Creates a new <code>ByteBuffer</code> that shares this buffer's
413 * content.
414 */
415 public abstract ByteBuffer duplicate ();
416
417 /**
418 * Creates a new read-only <code>ByteBuffer</code> that shares this
419 * buffer's content.
420 */
421 public abstract ByteBuffer asReadOnlyBuffer ();
422
423 /**
424 * Creates a view of this byte buffer as a short buffer.
425 */
426 public abstract ShortBuffer asShortBuffer ();
427
428 /**
429 * Creates a view of this byte buffer as a char buffer.
430 */
431 public abstract CharBuffer asCharBuffer ();
432
433 /**
434 * Creates a view of this byte buffer as an integer buffer.
435 */
436 public abstract IntBuffer asIntBuffer ();
437
438 /**
439 * Creates a view of this byte buffer as a long buffer.
440 */
441 public abstract LongBuffer asLongBuffer ();
442
443 /**
444 * Creates a view of this byte buffer as a float buffer.
445 */
446 public abstract FloatBuffer asFloatBuffer ();
447
448 /**
449 * Creates a view of this byte buffer as a double buffer.
450 */
451 public abstract DoubleBuffer asDoubleBuffer ();
452
453 /**
454 * Relative get method for reading a character value.
455 *
456 * @exception BufferUnderflowException If there are fewer than two bytes
457 * remaining in this buffer.
458 */
459 public abstract char getChar ();
460
461 /**
462 * Relative put method for writing a character value.
463 *
464 * @exception BufferOverflowException If this buffer's current position is
465 * not smaller than its limit.
466 */
467 public abstract ByteBuffer putChar (char value);
468
469 /**
470 * Absolute get method for reading a character value.
471 *
472 * @exception IndexOutOfBoundsException If there are fewer than two bytes
473 * remaining in this buffer
474 */
475 public abstract char getChar (int index);
476
477 /**
478 * Absolute put method for writing a character value.
479 *
480 * @exception IndexOutOfBoundsException If index is negative or not smaller
481 * than the buffer's limit, minus one.
482 */
483 public abstract ByteBuffer putChar (int index, char value);
484
485 /**
486 * Relative get method for reading a short value.
487 *
488 * @exception BufferUnderflowException If index is negative or not smaller
489 * than the buffer's limit, minus one.
490 */
491 public abstract short getShort ();
492
493 /**
494 * Relative put method for writing a short value.
495 *
496 * @exception BufferOverflowException If this buffer's current position is
497 * not smaller than its limit.
498 */
499 public abstract ByteBuffer putShort (short value);
500
501 /**
502 * Absolute get method for reading a short value.
503 *
504 * @exception IndexOutOfBoundsException If there are fewer than two bytes
505 * remaining in this buffer
506 */
507 public abstract short getShort (int index);
508
509 /**
510 * Absolute put method for writing a short value.
511 *
512 * @exception IndexOutOfBoundsException If index is negative or not smaller
513 * than the buffer's limit, minus one.
514 */
515 public abstract ByteBuffer putShort (int index, short value);
516
517 /**
518 * Relative get method for reading an integer value.
519 *
520 * @exception BufferUnderflowException If there are fewer than four bytes
521 * remaining in this buffer.
522 */
523 public abstract int getInt ();
524
525 /**
526 * Relative put method for writing an integer value.
527 *
528 * @exception BufferOverflowException If this buffer's current position is
529 * not smaller than its limit.
530 */
531 public abstract ByteBuffer putInt (int value);
532
533 /**
534 * Absolute get method for reading an integer value.
535 *
536 * @exception IndexOutOfBoundsException If index is negative or not smaller
537 * than the buffer's limit, minus three.
538 */
539 public abstract int getInt (int index);
540
541 /**
542 * Absolute put method for writing an integer value.
543 *
544 * @exception IndexOutOfBoundsException If index is negative or not smaller
545 * than the buffer's limit, minus three.
546 */
547 public abstract ByteBuffer putInt (int index, int value);
548
549 /**
550 * Relative get method for reading a long value.
551 *
552 * @exception BufferUnderflowException If there are fewer than eight bytes
553 * remaining in this buffer.
554 */
555 public abstract long getLong ();
556
557 /**
558 * Relative put method for writing a long value.
559 *
560 * @exception BufferOverflowException If this buffer's current position is
561 * not smaller than its limit.
562 */
563 public abstract ByteBuffer putLong (long value);
564
565 /**
566 * Absolute get method for reading a long value.
567 *
568 * @exception IndexOutOfBoundsException If index is negative or not smaller
569 * than the buffer's limit, minus seven.
570 */
571 public abstract long getLong (int index);
572
573 /**
574 * Absolute put method for writing a float value.
575 *
576 * @exception IndexOutOfBoundsException If index is negative or not smaller
577 * than the buffer's limit, minus seven.
578 */
579 public abstract ByteBuffer putLong (int index, long value);
580
581 /**
582 * Relative get method for reading a float value.
583 *
584 * @exception BufferUnderflowException If there are fewer than four bytes
585 * remaining in this buffer.
586 */
587 public abstract float getFloat ();
588
589 /**
590 * Relative put method for writing a float value.
591 *
592 * @exception BufferOverflowException If there are fewer than four bytes
593 * remaining in this buffer.
594 */
595 public abstract ByteBuffer putFloat (float value);
596
597 /**
598 * Absolute get method for reading a float value.
599 *
600 * @exception IndexOutOfBoundsException If index is negative or not smaller
601 * than the buffer's limit, minus three.
602 */
603 public abstract float getFloat (int index);
604
605 /**
606 * Relative put method for writing a float value.
607 *
608 * @exception IndexOutOfBoundsException If index is negative or not smaller
609 * than the buffer's limit, minus three.
610 */
611 public abstract ByteBuffer putFloat (int index, float value);
612
613 /**
614 * Relative get method for reading a double value.
615 *
616 * @exception BufferUnderflowException If there are fewer than eight bytes
617 * remaining in this buffer.
618 */
619 public abstract double getDouble ();
620
621 /**
622 * Relative put method for writing a double value.
623 *
624 * @exception BufferOverflowException If this buffer's current position is
625 * not smaller than its limit.
626 */
627 public abstract ByteBuffer putDouble (double value);
628
629 /**
630 * Absolute get method for reading a double value.
631 *
632 * @exception IndexOutOfBoundsException If index is negative or not smaller
633 * than the buffer's limit, minus seven.
634 */
635 public abstract double getDouble (int index);
636
637 /**
638 * Absolute put method for writing a double value.
639 *
640 * @exception IndexOutOfBoundsException If index is negative or not smaller
641 * than the buffer's limit, minus seven.
642 */
643 public abstract ByteBuffer putDouble (int index, double value);
644
645 /**
646 * Returns a string summarizing the state of this buffer.
647 */
648 public String toString ()
649 {
650 return getClass ().getName () +
651 "[pos=" + position () +
652 " lim=" + limit () +
653 " cap=" + capacity () + "]";
654 }
655 }