beagled/Lucene.Net/Store/RAMInputStream.cs

   1 /*
   2  * Copyright 2004 The Apache Software Foundation
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  * http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16 using System;
  17 namespace Lucene.Net.Store
  18 {
  19         /// <summary> A memory-resident {@link InputStream} implementation.
  20         ///
  21         /// </summary>
  22         /// <version>  $Id: RAMInputStream.cs,v 1.2 2005/10/06 19:29:58 dsd Exp $
  23         /// </version>
  24
  25         class RAMInputStream : BufferedIndexInput, System.ICloneable
  26         {
  27                 private RAMFile file;
  28                 private int pointer = 0;
  29         private long length;
  30
  31                 public RAMInputStream(RAMFile f)
  32                 {
  33                         file = f;
  34                         length = file.length;
  35                 }
  36
  37                 public override void  ReadInternal(byte[] dest, int destOffset, int len)
  38                 {
  39                         int remainder = len;
  40                         int start = pointer;
  41                         while (remainder != 0)
  42                         {
  43                                 int bufferNumber = start / BUFFER_SIZE;
  44                                 int bufferOffset = start % BUFFER_SIZE;
  45                                 int bytesInBuffer = BUFFER_SIZE - bufferOffset;
  46                                 int bytesToCopy = bytesInBuffer >= remainder?remainder:bytesInBuffer;
  47                                 byte[] buffer = (byte[]) file.buffers[bufferNumber];
  48                                 Array.Copy(buffer, bufferOffset, dest, destOffset, bytesToCopy);
  49                                 destOffset += bytesToCopy;
  50                                 start += bytesToCopy;
  51                                 remainder -= bytesToCopy;
  52                         }
  53                         pointer += len;
  54                 }
  55
  56                 public override void  Close()
  57                 {
  58                 }
  59
  60                 public override void  SeekInternal(long pos)
  61                 {
  62                         pointer = (int) pos;
  63                 }
  64
  65         public override long Length()
  66         {
  67             return length;
  68         }
  69     }
  70 }