libjava/classpath/java/nio/ByteBuffer.java

   1 /* ByteBuffer.java --
   2    Copyright (C) 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
   3
   4 This file is part of GNU Classpath.
   5
   6 GNU Classpath is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Classpath is distributed in the hope that it will be useful, but
  12 WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Classpath; see the file COPYING.  If not, write to the
  18 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19 02110-1301 USA.
  20
  21 Linking this library statically or dynamically with other modules is
  22 making a combined work based on this library.  Thus, the terms and
  23 conditions of the GNU General Public License cover the whole
  24 combination.
  25
  26 As a special exception, the copyright holders of this library give you
  27 permission to link this library with independent modules to produce an
  28 executable, regardless of the license terms of these independent
  29 modules, and to copy and distribute the resulting executable under
  30 terms of your choice, provided that you also meet, for each linked
  31 independent module, the terms and conditions of the license of that
  32 module.  An independent module is a module which is not derived from
  33 or based on this library.  If you modify this library, you may extend
  34 this exception to your version of the library, but you are not
  35 obligated to do so.  If you do not wish to do so, delete this
  36 exception statement from your version. */
  37
  38
  39 package java.nio;
  40
  41 // GCJ LOCAL: Change gnu.classpath.Pointer to RawData
  42 import gnu.gcj.RawData;
  43 import gnu.classpath.Pointer;
  44
  45 /**
  46  * @since 1.4
  47  */
  48 public abstract class ByteBuffer extends Buffer
  49   implements Comparable<ByteBuffer>
  50 {
  51   ByteOrder endian = ByteOrder.BIG_ENDIAN;
  52   final byte[] backing_buffer;
  53   final int array_offset;
  54
  55   ByteBuffer (int capacity, int limit, int position, int mark,
  56               RawData address, byte[] backing_buffer, int array_offset)
  57   {
  58     super (capacity, limit, position, mark, address);
  59     this.backing_buffer = backing_buffer;
  60     this.array_offset = array_offset;
  61   }
  62
  63   /**
  64    * Allocates a new direct byte buffer.
  65    */
  66   public static ByteBuffer allocateDirect (int capacity)
  67   {
  68     return DirectByteBufferImpl.allocate (capacity);
  69   }
  70
  71   /**
  72    * Allocates a new <code>ByteBuffer</code> object with a given capacity.
  73    */
  74   public static ByteBuffer allocate (int capacity)
  75   {
  76     return wrap(new byte[capacity], 0, capacity);
  77   }
  78
  79   /**
  80    * Wraps a <code>byte</code> array into a <code>ByteBuffer</code>
  81    * object.
  82    *
  83    * @exception IndexOutOfBoundsException If the preconditions on the offset
  84    * and length parameters do not hold
  85    */
  86   public static final ByteBuffer wrap (byte[] array, int offset, int length)
  87   {
  88     // FIXME: In GCJ and other implementations where arrays may not
  89     // move we might consider, at least when offset==0:
  90     // return new DirectByteBufferImpl(array,
  91     //                                 address_of_data(array) + offset,
  92     //                                 length, length, 0, false);
  93     // This may be more efficient, mainly because we can then use the
  94     // same logic for all ByteBuffers.
  95
  96     return new ByteBufferImpl (array, 0, array.length, offset + length, offset, -1, false);
  97   }
  98
  99   /**
 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 }