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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
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;
namespace MS.Internal.Ink.InkSerializedFormat
{
/// <summary>
/// HuffCodec
/// </summary>
internal class HuffCodec
{
/// <summary>
/// HuffCodec
/// </summary>
/// <param name="defaultIndex"></param>
internal HuffCodec(uint defaultIndex)
{
HuffBits bits = new HuffBits();
bits.InitBits(defaultIndex);
InitHuffTable(bits);
}
/// <summary>
/// InitHuffTable
/// </summary>
/// <param name="huffBits"></param>
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));
}
}
/// <summary>
/// Compress
/// </summary>
/// <param name="dataXf">can be null</param>
/// <param name="input">input array to compress</param>
/// <param name="compressedData"></param>
internal void Compress(DataXform dataXf, int[] input, List<byte> compressedData)
{
//
// use the writer to write to the list<byte>
//
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);
}
}
}
/// <summary>
/// Uncompress
/// </summary>
/// <param name="dtxf"></param>
/// <param name="input"></param>
/// <param name="startIndex"></param>
/// <param name="outputBuffer"></param>
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
}
/// <summary>
/// Encode
/// </summary>
/// <param name="data"></param>
/// <param name="extra"></param>
/// <param name="writer"></param>
/// <returns>number of bits encoded, 0 for failure</returns>
internal byte Encode(int data, int extra, BitStreamWriter writer)
{
ArgumentNullException.ThrowIfNull(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);
}
/// <summary>
/// Decode
/// </summary>
/// <param name="data"></param>
/// <param name="extra"></param>
/// <param name="reader"></param>
/// <returns>number of bits decoded, 0 for error</returns>
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"));
}
/// <summary>
/// Privates
/// </summary>
private HuffBits _huffBits;
private uint[] _mins = new uint[MaxBAASize];
/// <summary>
/// Private statics
/// </summary>
private const byte MaxBAASize = 10;
/// <summary>
/// Private helper class
/// </summary>
private class HuffBits
{
/// <summary>
/// HuffBits
/// </summary>
internal HuffBits()
{
_size = 2;
_bits[0] = 0;
_bits[1] = 32;
_matchIndex = 0;
_prefixCount = 1;
//_findMatch = true;
}
/// <summary>
/// InitBits
/// </summary>
/// <param name="defaultIndex"></param>
/// <returns></returns>
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;
}
/// <summary>
/// GetSize
/// </summary>
internal uint GetSize()
{
return _size;
}
/// <summary>
/// GetBitsAtIndex
/// </summary>
internal byte GetBitsAtIndex(uint index)
{
return _bits[(int)index];
}
/// <summary>
/// Privates
/// </summary>
private byte[] _bits = new byte[MaxBAASize];
private uint _size;
private uint _matchIndex;
private uint _prefixCount;
//private bool _findMatch;
/// <summary>
/// Private statics
/// </summary>
private const byte MaxBAASize = 10;
private const 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 };
}
}
}
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