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      1 /*
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      3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
      4  *
      5  * This code is free software; you can redistribute it and/or modify it
      6  * under the terms of the GNU General Public License version 2 only, as
      7  * published by the Free Software Foundation.  Oracle designates this
      8  * particular file as subject to the "Classpath" exception as provided
      9  * by Oracle in the LICENSE file that accompanied this code.
     10  *
     11  * This code is distributed in the hope that it will be useful, but WITHOUT
     12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
     13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
     14  * version 2 for more details (a copy is included in the LICENSE file that
     15  * accompanied this code).
     16  *
     17  * You should have received a copy of the GNU General Public License version
     18  * 2 along with this work; if not, write to the Free Software Foundation,
     19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
     20  *
     21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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     23  * questions.
     24  */
     25 
     26 package java.nio;
     27 
     28 import libcore.io.Memory;
     29 
     30 class ByteBufferAsDoubleBuffer
     31         extends DoubleBuffer {            // package-private
     32 
     33     protected final ByteBuffer bb;
     34     protected final int offset;
     35     private final ByteOrder order;
     36 
     37     ByteBufferAsDoubleBuffer(ByteBuffer bb,
     38                              int mark, int pos, int lim, int cap,
     39                              int off, ByteOrder order) {
     40         super(mark, pos, lim, cap);
     41         this.bb = bb.duplicate();
     42         this.isReadOnly = bb.isReadOnly;
     43         // There are only two possibilities for the type of ByteBuffer "bb", viz, DirectByteBuffer and
     44         // HeapByteBuffer. We only have to initialize the field when bb is an instance of
     45         // DirectByteBuffer.
     46         // The address field is used by NIOAccess#getBasePointer and GetDirectBufferAddress method
     47         // in art which return the address of the first usable byte of the underlying memory, i.e,
     48         // the position of parent buffer. Therefore, value of "off" will be equal to parent buffer's
     49         // position when the method is called from either HeapByteBuffer or DirectByteBuffer.
     50         if (bb instanceof DirectByteBuffer) {
     51             this.address = bb.address + off;
     52         }
     53         this.bb.order(order);
     54         this.order = order;
     55         offset = off;
     56     }
     57 
     58     public DoubleBuffer slice() {
     59         int pos = this.position();
     60         int lim = this.limit();
     61         assert (pos <= lim);
     62         int rem = (pos <= lim ? lim - pos : 0);
     63         int off = (pos << 3) + offset;
     64         assert (off >= 0);
     65         return new ByteBufferAsDoubleBuffer(bb, -1, 0, rem, rem, off, order);
     66     }
     67 
     68     public DoubleBuffer duplicate() {
     69         return new ByteBufferAsDoubleBuffer(bb,
     70                 markValue(),
     71                 position(),
     72                 limit(),
     73                 capacity(),
     74                 offset,
     75                 order);
     76     }
     77 
     78     public DoubleBuffer asReadOnlyBuffer() {
     79         return new ByteBufferAsDoubleBuffer(bb.asReadOnlyBuffer(),
     80                 markValue(),
     81                 position(),
     82                 limit(),
     83                 capacity(),
     84                 offset,
     85                 order);
     86     }
     87 
     88     protected int ix(int i) {
     89         return (i << 3) + offset;
     90     }
     91 
     92     public double get() {
     93         return get(nextGetIndex());
     94     }
     95 
     96     public double get(int i) {
     97         return bb.getDoubleUnchecked(ix(checkIndex(i)));
     98     }
     99 
    100     public DoubleBuffer get(double[] dst, int offset, int length) {
    101         checkBounds(offset, length, dst.length);
    102         if (length > remaining())
    103             throw new BufferUnderflowException();
    104         bb.getUnchecked(ix(position), dst, offset, length);
    105         position += length;
    106         return this;
    107     }
    108 
    109     public DoubleBuffer put(double x) {
    110         put(nextPutIndex(), x);
    111         return this;
    112     }
    113 
    114     public DoubleBuffer put(int i, double x) {
    115         if (isReadOnly) {
    116             throw new ReadOnlyBufferException();
    117         }
    118         bb.putDoubleUnchecked(ix(checkIndex(i)), x);
    119         return this;
    120     }
    121 
    122     public DoubleBuffer put(double[] src, int offset, int length) {
    123         checkBounds(offset, length, src.length);
    124         if (length > remaining())
    125             throw new BufferOverflowException();
    126         bb.putUnchecked(ix(position), src, offset, length);
    127         position += length;
    128         return this;
    129     }
    130 
    131     public DoubleBuffer compact() {
    132         if (isReadOnly) {
    133             throw new ReadOnlyBufferException();
    134         }
    135         int pos = position();
    136         int lim = limit();
    137         assert (pos <= lim);
    138         int rem = (pos <= lim ? lim - pos : 0);
    139         if (!(bb instanceof DirectByteBuffer)) {
    140             System.arraycopy(bb.array(), ix(pos), bb.array(), ix(0), rem << 3);
    141         } else {
    142             Memory.memmove(this, ix(0), this, ix(pos), rem << 3);
    143         }
    144         position(rem);
    145         limit(capacity());
    146         discardMark();
    147         return this;
    148     }
    149 
    150     public boolean isDirect() {
    151         return bb.isDirect();
    152     }
    153 
    154     public boolean isReadOnly() {
    155         return isReadOnly;
    156     }
    157 
    158     public ByteOrder order() {
    159         return order;
    160     }
    161 }
    162