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