Code:
/ DotNET / DotNET / 8.0 / untmp / WIN_WINDOWS / lh_tools_devdiv_wpf / Windows / wcp / Core / MS / Internal / Ink / InkSerializedFormat / HuffCodec.cs / 1 / HuffCodec.cs
using MS.Utility; using System; using System.Runtime.InteropServices; using System.Security; using System.Globalization; using System.Windows; using System.Windows.Input; using System.Collections.Generic; using System.Windows.Ink; using MS.Internal.Ink.InkSerializedFormat; using System.Diagnostics; using SR = MS.Internal.PresentationCore.SR; using SRID = MS.Internal.PresentationCore.SRID; namespace MS.Internal.Ink.InkSerializedFormat { ////// HuffCodec /// internal class HuffCodec { ////// HuffCodec /// /// internal HuffCodec(uint defaultIndex) { HuffBits bits = new HuffBits(); bits.InitBits(defaultIndex); InitHuffTable(bits); } ////// InitHuffTable /// /// private void InitHuffTable(HuffBits huffBits) { _huffBits = huffBits; uint bitSize = _huffBits.GetSize(); int lowerBound = 1; _mins[0] = 0; for (uint n = 1; n < bitSize; n++) { _mins[n] = (uint)lowerBound; lowerBound += (1 << (_huffBits.GetBitsAtIndex(n) - 1)); } } ////// Compress /// /// can be null /// input array to compress /// internal void Compress(DataXform dataXf, int[] input, ListcompressedData) { // // use the writer to write to the list // BitStreamWriter writer = new BitStreamWriter(compressedData); if (null != dataXf) { dataXf.ResetState(); int xfData = 0; int xfExtra = 0; for (uint i = 0; i < input.Length; i++) { dataXf.Transform(input[i], ref xfData, ref xfExtra); Encode(xfData, xfExtra, writer); } } else { for (uint i = 0; i < input.Length; i++) { Encode(input[i], 0, writer); } } } /// /// Uncompress /// /// /// /// /// internal uint Uncompress(DataXform dtxf, byte[] input, int startIndex, int[] outputBuffer) { Debug.Assert(input != null); Debug.Assert(input.Length >= 2); Debug.Assert(startIndex == 1); Debug.Assert(outputBuffer != null); Debug.Assert(outputBuffer.Length != 0); BitStreamReader reader = new BitStreamReader(input, startIndex); int xfExtra = 0, xfData = 0; int outputBufferIndex = 0; if (null != dtxf) { dtxf.ResetState(); while (!reader.EndOfStream) { Decode(ref xfData, ref xfExtra, reader); int uncompressed = dtxf.InverseTransform(xfData, xfExtra); Debug.Assert(outputBufferIndex < outputBuffer.Length); outputBuffer[outputBufferIndex++] = uncompressed; if (outputBufferIndex == outputBuffer.Length) { //only write as much as the outputbuffer can hold //this is assumed by calling code break; } } } else { while (!reader.EndOfStream) { Decode(ref xfData, ref xfExtra, reader); Debug.Assert(outputBufferIndex < outputBuffer.Length); outputBuffer[outputBufferIndex++] = xfData; if (outputBufferIndex == outputBuffer.Length) { //only write as much as the outputbuffer can hold //this is assumed by calling code break; } } } return (uint)((reader.CurrentIndex + 1) - startIndex); //we include startIndex in the read count } ////// Encode /// /// /// /// ///number of bits encoded, 0 for failure internal byte Encode(int data, int extra, BitStreamWriter writer) { if (writer == null) { throw new ArgumentNullException("writer"); } if (data == 0) { writer.Write((byte)0, 1); //more efficent return (byte)1; } // First, encode extra if non-ZERO uint bitSize = _huffBits.GetSize(); if (0 != extra) { // Prefix lenght is 1 more than table size byte extraPrefixLength = (byte)(bitSize + 1); int extraPrefix = ((1 << extraPrefixLength) - 2); writer.Write((uint)extraPrefix, (int)extraPrefixLength); // Encode the extra data first byte extraCodeLength = Encode(extra, 0, writer); // Encode the actual data next byte dataCodeLength = Encode(data, 0, writer); // Return the total code lenght return (byte)((int)extraPrefixLength + (int)extraCodeLength + (int)dataCodeLength); } // Find the absolute value of the data // IMPORTANT : It is extremely important that nData is uint, and NOT int // If it is int, the LONG_MIN will be encoded erroneaouly uint nData = (uint)MathHelper.AbsNoThrow(data); // Find the prefix lenght byte nPrefLen = 1; for (; (nPrefLen < bitSize) && (nData >= _mins[nPrefLen]); ++nPrefLen) ; // Get the data length uint nDataLen = _huffBits.GetBitsAtIndex((uint)nPrefLen - 1); // Find the prefix int nPrefix = ((1 << nPrefLen) - 2); // Append the prefix to the bit stream writer.Write((uint)nPrefix, (int)nPrefLen); // Find the data offset by lower bound // and append sign bit at LSB Debug.Assert(nDataLen > 0 && nDataLen - 1 <= Int32.MaxValue); int dataLenMinusOne = (int)(nDataLen - 1); //can't left shift by a uint, we need to thunk to an int nData = ((((nData - _mins[nPrefLen - 1]) & (uint)((1 << dataLenMinusOne) - 1)) << 1) | (uint)((data < 0) ? 1 : 0)); // Append data into the bit streamdataLenMinusOne Debug.Assert(nDataLen <= Int32.MaxValue); writer.Write(nData, (int)nDataLen); return (byte)((uint)nPrefLen + nDataLen); } ////// Decode /// /// /// /// ///number of bits decoded, 0 for error internal void Decode(ref int data, ref int extra, BitStreamReader reader) { // Find the prefix length byte prefIndex = 0; while (reader.ReadBit()) { prefIndex++; } // First indicate there is no extra data extra = 0; // More efficient for 0 if (0 == prefIndex) { data = 0; return; } else if (prefIndex < _huffBits.GetSize()) { // Find the data lenght uint nDataLen = _huffBits.GetBitsAtIndex(prefIndex); // Extract the offset data by lower dound with sign bit at LSB long nData = reader.ReadUInt64((int)(byte)nDataLen); // Find the sign bit bool bNeg = ((nData & 0x01) != 0); // Construct the data nData = (nData >> 1) + _mins[prefIndex]; // Adjust the sign bit data = bNeg ? -((int)nData) : (int)nData; // return the bit count read from stream return; } else if (prefIndex == _huffBits.GetSize()) { // This is the special prefix for extra data. // Decode the prefix first int extra2 = 0; int extra2Ignored = 0; Decode(ref extra2, ref extra2Ignored, reader); extra = extra2; // Following is the actual data int data2 = 0; Decode(ref data2, ref extra2Ignored, reader); data = data2; return; } throw new ArgumentException(StrokeCollectionSerializer.ISFDebugMessage("invalid huffman encoded data")); } ////// Privates /// private HuffBits _huffBits; private uint[] _mins = new uint[MaxBAASize]; ////// Private statics /// private static readonly byte MaxBAASize = 10; ////// Private helper class /// private class HuffBits { ////// HuffBits /// internal HuffBits() { _size = 2; _bits[0] = 0; _bits[1] = 32; _matchIndex = 0; _prefixCount = 1; //_findMatch = true; } ////// InitBits /// /// ///internal bool InitBits(uint defaultIndex) { if (defaultIndex < DefaultBAACount && DefaultBAASize[defaultIndex] <= MaxBAASize) { _size = DefaultBAASize[defaultIndex]; _matchIndex = defaultIndex; _prefixCount = _size; //_findMatch = true; _bits = DefaultBAAData[defaultIndex]; return true; } return false; } /// /// GetSize /// internal uint GetSize() { return _size; } ////// GetBitsAtIndex /// internal byte GetBitsAtIndex(uint index) { return _bits[(int)index]; } ////// Privates /// private byte[] _bits = new byte[MaxBAASize]; private uint _size; private uint _matchIndex; private uint _prefixCount; //private bool _findMatch; ////// Private statics /// private static readonly byte MaxBAASize = 10; private static readonly byte DefaultBAACount = 8; private static readonly byte[][] DefaultBAAData = new byte[][] { new byte[]{0, 1, 2, 4, 6, 8, 12, 16, 24, 32}, new byte[]{0, 1, 1, 2, 4, 8, 12, 16, 24, 32}, new byte[]{0, 1, 1, 1, 2, 4, 8, 14, 22, 32}, new byte[]{0, 2, 2, 3, 5, 8, 12, 16, 24, 32}, new byte[]{0, 3, 4, 5, 8, 12, 16, 24, 32, 0}, new byte[]{0, 4, 6, 8, 12, 16, 24, 32, 0, 0}, new byte[]{0, 6, 8, 12, 16, 24, 32, 0, 0, 0}, new byte[]{0, 7, 8, 12, 16, 24, 32, 0, 0, 0}, }; private static readonly byte[] DefaultBAASize = new byte[] { 10, 10, 10, 10, 9, 8, 7, 7 }; } } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007. // Copyright (c) Microsoft Corporation. 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