LibHac/libhac.Nand/DiscUtils.Core/Compression/MoveToFront.cs

//
// Copyright (c) 2008-2011, Kenneth Bell
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
//

namespace DiscUtils.Compression
{
    internal class MoveToFront
    {
        private readonly byte[] _buffer;

        public MoveToFront()
            : this(256, false) {}

        public MoveToFront(int size, bool autoInit)
        {
            _buffer = new byte[size];

            if (autoInit)
            {
                for (byte i = 0; i < size; ++i)
                {
                    _buffer[i] = i;
                }
            }
        }

        public byte Head
        {
            get { return _buffer[0]; }
        }

        public void Set(int pos, byte val)
        {
            _buffer[pos] = val;
        }

        public byte GetAndMove(int pos)
        {
            byte val = _buffer[pos];

            for (int i = pos; i > 0; --i)
            {
                _buffer[i] = _buffer[i - 1];
            }

            _buffer[0] = val;
            return val;
        }
    }
}