Source for gnu.CORBA.CDR.AligningInput

   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: }