/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Mozilla Universal charset detector code.
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 2001
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *          Kohei TAKETA <k-tak@void.in> (Java port)
 *          Rudi Pettazzi <rudi.pettazzi@gmail.com> (C# port)
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

namespace UniversalDetector.Core
{
    public class BitPackage
    {
        public static int INDEX_SHIFT_4BITS  = 3;
        public static int INDEX_SHIFT_8BITS  = 2;
        public static int INDEX_SHIFT_16BITS = 1;
        
        public static int SHIFT_MASK_4BITS  = 7;
        public static int SHIFT_MASK_8BITS  = 3;
        public static int SHIFT_MASK_16BITS = 1;
        
        public static int BIT_SHIFT_4BITS  = 2;
        public static int BIT_SHIFT_8BITS  = 3;
        public static int BIT_SHIFT_16BITS = 4;
        
        public static int UNIT_MASK_4BITS  = 0x0000000F;
        public static int UNIT_MASK_8BITS  = 0x000000FF;
        public static int UNIT_MASK_16BITS = 0x0000FFFF;

        private int indexShift;
        private int shiftMask;
        private int bitShift;
        private int unitMask;
        private int[] data;
        
        public BitPackage(int indexShift, int shiftMask,
                int bitShift, int unitMask, int[] data)
        {
            this.indexShift = indexShift;
            this.shiftMask = shiftMask;
            this.bitShift = bitShift;
            this.unitMask = unitMask;
            this.data = data;
        }
        
        public static int Pack16bits(int a, int b)
        {
            return ((b << 16) | a);
        }
        
        public static int Pack8bits(int a, int b, int c, int d)
        {
            return Pack16bits((b << 8) | a, (d << 8) | c);
        }
        
        public static int Pack4bits(int a, int b, int c, int d, 
                                    int e, int f, int g, int h)
        {
            return Pack8bits((b << 4) | a, (d << 4) | c,
                             (f << 4) | e, (h << 4) | g);
        }
        
        public int Unpack(int i)
        {
            return (data[i >> indexShift] >> 
                    ((i & shiftMask) << bitShift)) & unitMask;
        }
   }
}