old-autovect-branch/libjava/classpath/gnu/CORBA/CDR/AligningInput.java

   1 /* AligningInput.java --
   2    Copyright (C) 2005 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., 51 Franklin Street, Fifth Floor, Boston, MA
  19 02110-1301 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 gnu.CORBA.CDR;
  40
  41 import java.io.ByteArrayInputStream;
  42
  43 import org.omg.CORBA.BAD_PARAM;
  44
  45 /**
  46  * The input stream with the possibility to align on the
  47  * word (arbitrary size) boundary.
  48  *
  49  * @author Audrius Meskauskas (AudriusA@Bioinformatics.org)
  50  */
  51 public class AligningInput
  52   extends ByteArrayInputStream
  53 {
  54   /**
  55    * The alignment offset.
  56    */
  57   private int offset = 0;
  58
  59   /**
  60    * Create a stream, reading form the given buffer.
  61    *
  62    * @param a_buffer a buffer to read from.
  63    */
  64   public AligningInput(byte[] a_buffer)
  65   {
  66     super(a_buffer);
  67   }
  68
  69   /**
  70    * Set the alignment offset, if the index of the first byte in the
  71    * stream is different from 0.
  72    */
  73   public void setOffset(int an_offset)
  74   {
  75     offset = an_offset;
  76   }
  77
  78   /**
  79    * Skip several bytes, aligning the internal pointer on the
  80    * selected boundary.
  81    *
  82    * @throws BAD_PARAM, minor code 0, the alignment is not possible,
  83    * usually due the wrong parameter value.
  84    */
  85   public void align(int alignment)
  86   {
  87     try
  88       {
  89         int d = (pos + offset) % alignment;
  90         if (d > 0)
  91           {
  92             skip(alignment - d);
  93           }
  94       }
  95     catch (Exception ex)
  96       {
  97         BAD_PARAM p = new BAD_PARAM("Unable to align at " + alignment);
  98         p.initCause(ex);
  99         throw p;
 100       }
 101   }
 102
 103   /**
 104    * Get the byte buffer, from where the data are read.
 105    */
 106   public byte[] getBuffer()
 107   {
 108     return buf;
 109   }
 110
 111   /**
 112    * Get the current position in the buffer.
 113    *
 114    * @return The position in the buffer, taking offset into consideration.
 115    */
 116   public int getPosition()
 117   {
 118     return pos + offset;
 119   }
 120
 121   /**
 122    * Jump to the given position, taking offset into consideration.
 123    */
 124   public void seek(int position)
 125   {
 126     if (position < offset || position > (count+offset))
 127       throw new ArrayIndexOutOfBoundsException(position
 128         + " is out of valid ["+offset+".." + (count+offset) + "[ range");
 129     pos = position - offset;
 130   }
 131 }