eef9209c5d
* SecondLife.Directory is now properly initialized * Added BitPack class (and unit test) for decoding an arbitrary number of bytes from a byte array git-svn-id: http://libopenmetaverse.googlecode.com/svn/trunk@928 52acb1d6-8a22-11de-b505-999d5b087335
110 lines
3.5 KiB
C#
110 lines
3.5 KiB
C#
/*
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* Copyright (c) 2007, Second Life Reverse Engineering Team
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* All rights reserved.
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*
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* - Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* - Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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* - Neither the name of the Second Life Reverse Engineering Team nor the names
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* of its contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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using System;
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namespace libsecondlife
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{
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public class BitPack
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{
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private const int MAX_BITS = 8;
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private byte[] Data;
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private int bytePos;
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private int bitPos;
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public BitPack(byte[] data, int pos)
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{
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Data = data;
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bytePos = pos;
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}
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public float UnpackFloat()
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{
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byte[] output = UnpackBitsArray(32);
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if (!BitConverter.IsLittleEndian) Array.Reverse(output);
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return BitConverter.ToSingle(output, 0);
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}
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public int UnpackBits(int totalCount)
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{
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byte[] output = UnpackBitsArray(totalCount);
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if (!BitConverter.IsLittleEndian) Array.Reverse(output);
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return BitConverter.ToInt32(output, 0);
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}
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private byte[] UnpackBitsArray(int totalCount)
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{
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int count = 0;
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byte[] output = new byte[4];
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int curBytePos = 0;
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int curBitPos = 0;
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while (totalCount > 0)
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{
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if (totalCount > MAX_BITS)
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{
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count = MAX_BITS;
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totalCount -= MAX_BITS;
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}
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else
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{
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count = totalCount;
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totalCount = 0;
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}
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while (count > 0)
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{
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// Shift the previous bits
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output[curBytePos] <<= 1;
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// Grab one bit
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if ((Data[bytePos] & (0x80 >> bitPos++)) != 0)
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++output[curBytePos];
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--count;
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++curBitPos;
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if (bitPos >= MAX_BITS)
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{
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bitPos = 0;
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++bytePos;
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}
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if (curBitPos >= MAX_BITS)
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{
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curBitPos = 0;
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++curBytePos;
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}
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}
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}
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return output;
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}
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}
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}
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