libjava/java/nio/DoubleBuffer.java

   1 /* DoubleBuffer.java --
   2    Copyright (C) 2002, 2003, 2004  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., 59 Temple Place, Suite 330, Boston, MA
  19 02111-1307 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 /**
  42  * @since 1.4
  43  */
  44 public abstract class DoubleBuffer extends Buffer
  45   implements Comparable
  46 {
  47   int array_offset;
  48   double[] backing_buffer;
  49
  50   DoubleBuffer (int capacity, int limit, int position, int mark)
  51   {
  52     super (capacity, limit, position, mark);
  53     array_offset = 0;
  54   }
  55
  56   /**
  57    * Allocates a new <code>DoubleBuffer</code> object with a given capacity.
  58    */
  59   public static DoubleBuffer allocate (int capacity)
  60   {
  61     return new DoubleBufferImpl (capacity);
  62   }
  63
  64   /**
  65    * Wraps a <code>double</code> array into a <code>DoubleBuffer</code>
  66    * object.
  67    *
  68    * @exception IndexOutOfBoundsException If the preconditions on the offset
  69    * and length parameters do not hold
  70    */
  71   public static final DoubleBuffer wrap (double[] array, int offset, int length)
  72   {
  73     return new DoubleBufferImpl (array, 0, array.length, offset + length, offset, -1, false);
  74   }
  75
  76   /**
  77    * Wraps a <code>double</code> array into a <code>DoubleBuffer</code>
  78    * object.
  79    */
  80   public static final DoubleBuffer wrap (double[] array)
  81   {
  82     return wrap (array, 0, array.length);
  83   }
  84
  85   /**
  86    * This method transfers <code>double</code>s from this buffer into the given
  87    * destination array. Before the transfer, it checks if there are fewer than
  88    * length <code>double</code>s remaining in this buffer.
  89    *
  90    * @param dst The destination array
  91    * @param offset The offset within the array of the first <code>double</code>
  92    * to be written; must be non-negative and no larger than dst.length.
  93    * @param length The maximum number of bytes to be written to the given array;
  94    * must be non-negative and no larger than dst.length - offset.
  95    *
  96    * @exception BufferUnderflowException If there are fewer than length
  97    * <code>double</code>s remaining in this buffer.
  98    * @exception IndexOutOfBoundsException If the preconditions on the offset
  99    * and length parameters do not hold.
 100    */
 101   public DoubleBuffer get (double[] dst, int offset, int length)
 102   {
 103     checkArraySize(dst.length, offset, length);
 104     checkForUnderflow(length);
 105
 106     for (int i = offset; i < offset + length; i++)
 107       {
 108         dst [i] = get ();
 109       }
 110
 111     return this;
 112   }
 113
 114   /**
 115    * This method transfers <code>double</code>s from this buffer into the given
 116    * destination array.
 117    *
 118    * @param dst The byte array to write into.
 119    *
 120    * @exception BufferUnderflowException If there are fewer than dst.length
 121    * <code>double</code>s remaining in this buffer.
 122    */
 123   public DoubleBuffer get (double[] dst)
 124   {
 125     return get (dst, 0, dst.length);
 126   }
 127
 128   /**
 129    * Writes the content of the the <code>DoubleBUFFER</code> src
 130    * into the buffer. Before the transfer, it checks if there is fewer than
 131    * <code>src.remaining()</code> space remaining in this buffer.
 132    *
 133    * @param src The source data.
 134    *
 135    * @exception BufferOverflowException If there is insufficient space in this
 136    * buffer for the remaining <code>double</code>s in the source buffer.
 137    * @exception IllegalArgumentException If the source buffer is this buffer.
 138    * @exception ReadOnlyBufferException If this buffer is read-only.
 139    */
 140   public DoubleBuffer put (DoubleBuffer src)
 141   {
 142     if (src == this)
 143       throw new IllegalArgumentException ();
 144
 145     checkForOverflow(src.remaining ());
 146
 147     if (src.remaining () > 0)
 148       {
 149         double[] toPut = new double [src.remaining ()];
 150         src.get (toPut);
 151         put (toPut);
 152       }
 153
 154     return this;
 155   }
 156
 157   /**
 158    * Writes the content of the the <code>double array</code> src
 159    * into the buffer. Before the transfer, it checks if there is fewer than
 160    * length space remaining in this buffer.
 161    *
 162    * @param src The array to copy into the buffer.
 163    * @param offset The offset within the array of the first byte to be read;
 164    * must be non-negative and no larger than src.length.
 165    * @param length The number of bytes to be read from the given array;
 166    * must be non-negative and no larger than src.length - offset.
 167    *
 168    * @exception BufferOverflowException If there is insufficient space in this
 169    * buffer for the remaining <code>double</code>s in the source array.
 170    * @exception IndexOutOfBoundsException If the preconditions on the offset
 171    * and length parameters do not hold
 172    * @exception ReadOnlyBufferException If this buffer is read-only.
 173    */
 174   public DoubleBuffer put (double[] src, int offset, int length)
 175   {
 176     checkArraySize(src.length, offset, length);
 177     checkForOverflow(length);
 178
 179     for (int i = offset; i < offset + length; i++)
 180       put (src [i]);
 181
 182     return this;
 183   }
 184
 185   /**
 186    * Writes the content of the the <code>double array</code> src
 187    * into the buffer.
 188    *
 189    * @param src The array to copy into the buffer.
 190    *
 191    * @exception BufferOverflowException If there is insufficient space in this
 192    * buffer for the remaining <code>double</code>s in the source array.
 193    * @exception ReadOnlyBufferException If this buffer is read-only.
 194    */
 195   public final DoubleBuffer put (double[] src)
 196   {
 197     return put (src, 0, src.length);
 198   }
 199
 200   /**
 201    * Tells whether ot not this buffer is backed by an accessible
 202    * <code>double</code> array.
 203    */
 204   public final boolean hasArray ()
 205   {
 206     return (backing_buffer != null
 207             && !isReadOnly ());
 208   }
 209
 210   /**
 211    * Returns the <code>double</code> array that backs this buffer.
 212    *
 213    * @exception ReadOnlyBufferException If this buffer is read-only.
 214    * @exception UnsupportedOperationException If this buffer is not backed
 215    * by an accessible array.
 216    */
 217   public final double[] array ()
 218   {
 219     if (backing_buffer == null)
 220       throw new UnsupportedOperationException ();
 221
 222     checkIfReadOnly();
 223
 224     return backing_buffer;
 225   }
 226
 227   /**
 228    * Returns the offset within this buffer's backing array of the first element.
 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 int arrayOffset ()
 235   {
 236     if (backing_buffer == null)
 237       throw new UnsupportedOperationException ();
 238
 239     checkIfReadOnly();
 240
 241     return array_offset;
 242   }
 243
 244   /**
 245    * Calculates a hash code for this buffer.
 246    *
 247    * This is done with <code>long</code> arithmetic,
 248    * where ** represents exponentiation, by this formula:<br>
 249    * <code>s[position()] + 31 + (s[position()+1] + 30)*31**1 + ... +
 250    * (s[limit()-1]+30)*31**(limit()-1)</code>.
 251    * Where s is the buffer data, in Double.doubleToLongBits() form
 252    * Note that the hashcode is dependent on buffer content,
 253    * and therefore is not useful if the buffer content may change.
 254    *
 255    * @return the hash code (casted to int)
 256    */
 257   public int hashCode ()
 258   {
 259     long hashCode = Double.doubleToLongBits(get(position())) + 31;
 260     long multiplier = 1;
 261     for (int i = position() + 1; i < limit(); ++i)
 262       {
 263           multiplier *= 31;
 264           hashCode += (Double.doubleToLongBits(get(i)) + 30)*multiplier;
 265       }
 266     return ((int)hashCode);
 267   }
 268
 269   /**
 270    * Checks if this buffer is equal to obj.
 271    */
 272   public boolean equals (Object obj)
 273   {
 274     if (obj instanceof DoubleBuffer)
 275       {
 276         return compareTo (obj) == 0;
 277       }
 278
 279     return false;
 280   }
 281
 282   /**
 283    * Compares two <code>DoubleBuffer</code> objects.
 284    *
 285    * @exception ClassCastException If obj is not an object derived from
 286    * <code>DoubleBuffer</code>.
 287    */
 288   public int compareTo (Object obj)
 289   {
 290     DoubleBuffer other = (DoubleBuffer) obj;
 291
 292     int num = Math.min(remaining(), other.remaining());
 293     int pos_this = position();
 294     int pos_other = other.position();
 295
 296     for (int count = 0; count < num; count++)
 297       {
 298         double a = get(pos_this++);
 299         double b = other.get(pos_other++);
 300
 301         if (a == b)
 302           continue;
 303
 304         if (a < b)
 305           return -1;
 306
 307         return 1;
 308       }
 309
 310     return remaining() - other.remaining();
 311   }
 312
 313   /**
 314    * Returns the byte order of this buffer.
 315    */
 316   public abstract ByteOrder order ();
 317
 318   /**
 319    * Reads the <code>double</code> at this buffer's current position,
 320    * and then increments the position.
 321    *
 322    * @exception BufferUnderflowException If there are no remaining
 323    * <code>double</code>s in this buffer.
 324    */
 325   public abstract double get ();
 326
 327   /**
 328    * Writes the <code>double</code> at this buffer's current position,
 329    * and then increments the position.
 330    *
 331    * @exception BufferOverflowException If there no remaining
 332    * <code>double</code>s in this buffer.
 333    * @exception ReadOnlyBufferException If this buffer is read-only.
 334    */
 335   public abstract DoubleBuffer put (double b);
 336
 337   /**
 338    * Absolute get method.
 339    *
 340    * @exception IndexOutOfBoundsException If index is negative or not smaller
 341    * than the buffer's limit.
 342    */
 343   public abstract double get (int index);
 344
 345   /**
 346    * Absolute put method.
 347    *
 348    * @exception IndexOutOfBoundsException If index is negative or not smaller
 349    * than the buffer's limit.
 350    * @exception ReadOnlyBufferException If this buffer is read-only.
 351    */
 352   public abstract DoubleBuffer put (int index, double b);
 353
 354   /**
 355    * Compacts this buffer.
 356    *
 357    * @exception ReadOnlyBufferException If this buffer is read-only.
 358    */
 359   public abstract DoubleBuffer compact ();
 360
 361   /**
 362    * Tells wether or not this buffer is direct.
 363    */
 364   public abstract boolean isDirect ();
 365
 366   /**
 367    * Creates a new <code>DoubleBuffer</code> whose content is a shared
 368    * subsequence of this buffer's content.
 369    */
 370   public abstract DoubleBuffer slice ();
 371
 372   /**
 373    * Creates a new <code>DoubleBuffer</code> that shares this buffer's
 374    * content.
 375    */
 376   public abstract DoubleBuffer duplicate ();
 377
 378   /**
 379    * Creates a new read-only <code>DoubleBuffer</code> that shares this
 380    * buffer's content.
 381    */
 382   public abstract DoubleBuffer asReadOnlyBuffer ();
 383 }