libjava/gnu/java/net/protocol/core/CoreInputStream.java

   1 // Handler.java - URLStreamHandler for core protocol.
   2
   3 /* Copyright (C) 2001  Free Software Foundation
   4
   5    This file is part of libgcj.
   6
   7 This software is copyrighted work licensed under the terms of the
   8 Libgcj License.  Please consult the file "LIBGCJ_LICENSE" for
   9 details.  */
  10
  11 package gnu.java.net.protocol.core;
  12
  13 import gnu.gcj.Core;
  14 import gnu.gcj.RawData;
  15 import java.io.InputStream;
  16 import java.io.IOException;
  17
  18 public class CoreInputStream extends InputStream
  19 {
  20   /* A pointer to the object in memory.  */
  21   protected RawData ptr;
  22
  23   /* Position of the next byte in core to be read. */
  24   protected int pos;
  25
  26   /* The currently marked position in the stream. */
  27   protected int mark;
  28
  29   /* The index in core one greater than the last valid character. */
  30   protected int count;
  31
  32   private native int unsafeGetByte (long offset);
  33   private native int copyIntoByteArray (byte[] dest, int offset, int numBytes);
  34
  35   public CoreInputStream (Core core)
  36   {
  37     ptr = core.ptr;
  38     count = core.length;
  39   }
  40
  41   public synchronized int available()
  42   {
  43     return count - pos;
  44   }
  45
  46   public synchronized void mark(int readAheadLimit)
  47   {
  48     // readAheadLimit is ignored per Java Class Lib. book, p.220.
  49     mark = pos;
  50   }
  51
  52   public boolean markSupported()
  53   {
  54     return true;
  55   }
  56
  57   public synchronized int read()
  58   {
  59     if (pos < count)
  60       return ((int) unsafeGetByte(pos++)) & 0xFF;
  61     return -1;
  62   }
  63
  64   public synchronized int read(byte[] b, int off, int len)
  65   {
  66     if (pos >= count)
  67       return -1;
  68
  69     int numBytes = Math.min(count - pos, len);
  70     copyIntoByteArray (b, off, numBytes);
  71     pos += numBytes;
  72     return numBytes;
  73   }
  74
  75   public synchronized void reset()
  76   {
  77     pos = mark;
  78   }
  79
  80   public synchronized long skip(long n)
  81   {
  82     // Even though the var numBytes is a long, in reality it can never
  83     // be larger than an int since the result of subtracting 2 positive
  84     // ints will always fit in an int.  Since we have to return a long
  85     // anyway, numBytes might as well just be a long.
  86     long numBytes = Math.min ((long) (count - pos), n < 0 ? 0L : n);
  87     pos += numBytes;
  88     return numBytes;
  89   }
  90 }