001    /* LongBuffer.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    
044    /**
045     * @since 1.4
046     */
047    public abstract class LongBuffer extends Buffer
048      implements Comparable<LongBuffer>
049    {
050      final int array_offset;
051      final long[] backing_buffer;
052    
053      LongBuffer (int capacity, int limit, int position, int mark,
054                  RawData address, long[] backing_buffer, int array_offset)
055      {
056        super (capacity, limit, position, mark, address);
057        this.backing_buffer = backing_buffer;
058        this.array_offset = array_offset;
059      }
060    
061      /**
062       * Allocates a new <code>LongBuffer</code> object with a given capacity.
063       */
064      public static LongBuffer allocate (int capacity)
065      {
066        return new LongBufferImpl (capacity);
067      }
068    
069      /**
070       * Wraps a <code>long</code> array into a <code>LongBuffer</code>
071       * object.
072       *
073       * @exception IndexOutOfBoundsException If the preconditions on the offset
074       * and length parameters do not hold
075       */
076      public static final LongBuffer wrap (long[] array, int offset, int length)
077      {
078        return new LongBufferImpl (array, 0, array.length, offset + length, offset, -1, false);
079      }
080    
081      /**
082       * Wraps a <code>long</code> array into a <code>LongBuffer</code>
083       * object.
084       */
085      public static final LongBuffer wrap (long[] array)
086      {
087        return wrap (array, 0, array.length);
088      }
089      
090      /**
091       * This method transfers <code>long</code>s from this buffer into the given
092       * destination array. Before the transfer, it checks if there are fewer than
093       * length <code>long</code>s remaining in this buffer. 
094       *
095       * @param dst The destination array
096       * @param offset The offset within the array of the first <code>long</code>
097       * to be written; must be non-negative and no larger than dst.length.
098       * @param length The maximum number of bytes to be written to the given array;
099       * must be non-negative and no larger than dst.length - offset.
100       *
101       * @exception BufferUnderflowException If there are fewer than length
102       * <code>long</code>s remaining in this buffer.
103       * @exception IndexOutOfBoundsException If the preconditions on the offset
104       * and length parameters do not hold.
105       */
106      public LongBuffer get (long[] dst, int offset, int length)
107      {
108        checkArraySize(dst.length, offset, length);
109        checkForUnderflow(length);
110    
111        for (int i = offset; i < offset + length; i++)
112          {
113            dst [i] = get ();
114          }
115    
116        return this;
117      }
118    
119      /**
120       * This method transfers <code>long</code>s from this buffer into the given
121       * destination array.
122       *
123       * @param dst The byte array to write into.
124       *
125       * @exception BufferUnderflowException If there are fewer than dst.length
126       * <code>long</code>s remaining in this buffer.
127       */
128      public LongBuffer get (long[] dst)
129      {
130        return get (dst, 0, dst.length);
131      }
132    
133      /**
134       * Writes the content of the the <code>LongBUFFER</code> src
135       * into the buffer. Before the transfer, it checks if there is fewer than
136       * <code>src.remaining()</code> space remaining in this buffer.
137       *
138       * @param src The source data.
139       *
140       * @exception BufferOverflowException If there is insufficient space in this
141       * buffer for the remaining <code>long</code>s in the source buffer.
142       * @exception IllegalArgumentException If the source buffer is this buffer.
143       * @exception ReadOnlyBufferException If this buffer is read-only.
144       */
145      public LongBuffer put (LongBuffer src)
146      {
147        if (src == this)
148          throw new IllegalArgumentException ();
149    
150        checkForOverflow(src.remaining ());
151    
152        if (src.remaining () > 0)
153          {
154            long[] toPut = new long [src.remaining ()];
155            src.get (toPut);
156            put (toPut);
157          }
158    
159        return this;
160      }
161    
162      /**
163       * Writes the content of the the <code>long array</code> src
164       * into the buffer. Before the transfer, it checks if there is fewer than
165       * length space remaining in this buffer.
166       *
167       * @param src The array to copy into the buffer.
168       * @param offset The offset within the array of the first byte to be read;
169       * must be non-negative and no larger than src.length.
170       * @param length The number of bytes to be read from the given array;
171       * must be non-negative and no larger than src.length - offset.
172       * 
173       * @exception BufferOverflowException If there is insufficient space in this
174       * buffer for the remaining <code>long</code>s in the source array.
175       * @exception IndexOutOfBoundsException If the preconditions on the offset
176       * and length parameters do not hold
177       * @exception ReadOnlyBufferException If this buffer is read-only.
178       */
179      public LongBuffer put (long[] src, int offset, int length)
180      {
181        checkArraySize(src.length, offset, length);
182        checkForOverflow(length);
183    
184        for (int i = offset; i < offset + length; i++)
185          put (src [i]);
186    
187        return this;
188      }
189    
190      /**
191       * Writes the content of the the <code>long array</code> src
192       * into the buffer.
193       *
194       * @param src The array to copy into the buffer.
195       * 
196       * @exception BufferOverflowException If there is insufficient space in this
197       * buffer for the remaining <code>long</code>s in the source array.
198       * @exception ReadOnlyBufferException If this buffer is read-only.
199       */
200      public final LongBuffer put (long[] src)
201      {
202        return put (src, 0, src.length);
203      }
204    
205      /**
206       * Tells whether ot not this buffer is backed by an accessible
207       * <code>long</code> array.
208       */
209      public final boolean hasArray ()
210      {
211        return (backing_buffer != null
212                && !isReadOnly ());
213      }
214    
215      /**
216       * Returns the <code>long</code> array that backs this buffer.
217       *
218       * @exception ReadOnlyBufferException If this buffer is read-only.
219       * @exception UnsupportedOperationException If this buffer is not backed
220       * by an accessible array.
221       */
222      public final long[] array ()
223      {
224        if (backing_buffer == null)
225          throw new UnsupportedOperationException ();
226    
227        checkIfReadOnly();
228        
229        return backing_buffer;
230      }
231    
232      /**
233       * Returns the offset within this buffer's backing array of the first element.
234       *
235       * @exception ReadOnlyBufferException If this buffer is read-only.
236       * @exception UnsupportedOperationException If this buffer is not backed
237       * by an accessible array.
238       */
239      public final int arrayOffset ()
240      {
241        if (backing_buffer == null)
242          throw new UnsupportedOperationException ();
243    
244        checkIfReadOnly();
245        
246        return array_offset;
247      }
248    
249      /**
250       * Calculates a hash code for this buffer.
251       *
252       * This is done with <code>long</code> arithmetic,
253       * where ** represents exponentiation, by this formula:<br>
254       * <code>s[position()] + 31 + (s[position()+1] + 30)*31**1 + ... +
255       * (s[limit()-1]+30)*31**(limit()-1)</code>.
256       * Where s is the buffer data. Note that the hashcode is dependent
257       * on buffer content, and therefore is not useful if the buffer
258       * content may change.
259       *
260       * @return the hash code (casted to int)
261       */
262      public int hashCode ()
263      {
264        long hashCode = get(position()) + 31;
265        long multiplier = 1;
266        for (int i = position() + 1; i < limit(); ++i)
267          {
268              multiplier *= 31;
269              hashCode += (get(i) + 30)*multiplier;
270          }
271        return ((int)hashCode);
272      }
273    
274      /**
275       * Checks if this buffer is equal to obj.
276       */
277      public boolean equals (Object obj)
278      {
279        if (obj instanceof LongBuffer)
280          {
281            return compareTo ((LongBuffer) obj) == 0;
282          }
283    
284        return false;
285      }
286    
287      /**
288       * Compares two <code>LongBuffer</code> objects.
289       *
290       * @exception ClassCastException If obj is not an object derived from
291       * <code>LongBuffer</code>.
292       */
293      public int compareTo (LongBuffer other)
294      {
295        int num = Math.min(remaining(), other.remaining());
296        int pos_this = position();
297        int pos_other = other.position();
298        
299        for (int count = 0; count < num; count++)
300          {
301             long a = get(pos_this++);
302             long b = other.get(pos_other++);
303             
304             if (a == b)
305               continue;
306               
307             if (a < b)
308               return -1;
309               
310             return 1;
311          }
312          
313         return remaining() - other.remaining();
314      }
315    
316      /**
317       * Returns the byte order of this buffer.
318       */
319      public abstract ByteOrder order ();
320    
321      /**
322       * Reads the <code>long</code> at this buffer's current position,
323       * and then increments the position.
324       *
325       * @exception BufferUnderflowException If there are no remaining
326       * <code>long</code>s in this buffer.
327       */
328      public abstract long get ();
329    
330      /**
331       * Writes the <code>long</code> at this buffer's current position,
332       * and then increments the position.
333       *
334       * @exception BufferOverflowException If there no remaining 
335       * <code>long</code>s in this buffer.
336       * @exception ReadOnlyBufferException If this buffer is read-only.
337       */
338      public abstract LongBuffer put (long b);
339    
340      /**
341       * Absolute get method.
342       *
343       * @exception IndexOutOfBoundsException If index is negative or not smaller
344       * than the buffer's limit.
345       */
346      public abstract long get (int index);
347      
348      /**
349       * Absolute put method.
350       *
351       * @exception IndexOutOfBoundsException If index is negative or not smaller
352       * than the buffer's limit.
353       * @exception ReadOnlyBufferException If this buffer is read-only.
354       */
355      public abstract LongBuffer put (int index, long b);
356    
357      /**
358       * Compacts this buffer.
359       * 
360       * @exception ReadOnlyBufferException If this buffer is read-only.
361       */
362      public abstract LongBuffer compact ();
363    
364      /**
365       * Tells wether or not this buffer is direct.
366       */
367      public abstract boolean isDirect ();
368    
369      /**
370       * Creates a new <code>LongBuffer</code> whose content is a shared
371       * subsequence of this buffer's content.
372       */
373      public abstract LongBuffer slice ();
374    
375      /**
376       * Creates a new <code>LongBuffer</code> that shares this buffer's
377       * content.
378       */
379      public abstract LongBuffer duplicate ();
380    
381      /**
382       * Creates a new read-only <code>LongBuffer</code> that shares this
383       * buffer's content.
384       */
385      public abstract LongBuffer asReadOnlyBuffer ();
386    }