SabreTools/SabreTools.Compression
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Use constants from Models

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This commit is contained in:
Matt Nadareski
2023-09-22 15:46:45 -04:00
parent 38dd2a5caf
commit 5b785fb28f
2 changed files with 5 additions and 57 deletions
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53
MSZIP/Constants.cs
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@@ -1,53 +0,0 @@
namespace SabreTools.Compression.MSZIP
{
public static class Constants
{
/// <summary>
/// Alphabet for fixed Huffman encoding
/// </summary>
public static readonly byte[] FixedAlphabet = new byte[19]
{
16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15,
};
/// <summary>
/// Extra bits for length codes 257-285
/// </summary>
public static readonly byte[] MatchExtraBits = new byte[29]
{
0, 0, 0, 0, 0, 0, 0, 0, 1, 1,
1, 1, 2, 2, 2, 2, 3, 3, 3, 3,
4, 4, 4, 4, 5, 5, 5, 5, 0,
};
/// <summary>
/// Initial lengths for length codes 257-285
/// </summary>
public static readonly ushort[] MatchLengths = new ushort[29]
{
3, 4, 5, 6, 7, 8, 9, 10, 11, 13,
15, 17, 19, 23, 27, 31, 35, 43, 51, 59,
67, 83, 99, 115, 131, 163, 195, 227, 258,
};
/// <summary>
/// Extra bits for distance codes 0-29
/// </summary>
public static readonly byte[] DistanceExtraBits = new byte[30]
{
0, 0, 0, 0, 1, 1, 2, 2, 3, 3,
4, 4, 5, 5, 6, 6, 7, 7, 8, 8,
9, 9, 10, 10, 11, 11, 12, 12, 13, 13,
};
/// <summary>
/// Initial lengths for distance codes 0-29
/// </summary>
public static readonly ushort[] DistanceLengths = new ushort[30]
{
1, 2, 3, 4, 5, 7, 9, 13, 17, 25,
33, 49, 65, 97, 129, 193, 257, 385, 513, 769,
1025, 1537, 2049, 3073, 4097, 6145, 8193, 12289, 16385, 24577
};
}
}

9
MSZIP/DeflateDecompressor.cs
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@@ -4,6 +4,7 @@ using System.IO;
using System.Linq;
using SabreTools.Models.Compression.MSZIP;
using static SabreTools.Compression.MSZIP.Constants;
using static SabreTools.Models.Compression.MSZIP.Constants;
namespace SabreTools.Compression.MSZIP
{
@@ -140,11 +141,11 @@ namespace SabreTools.Compression.MSZIP
uint[] lengthLengths = new uint[19];
for (int i = 0; i < numLength; i++)
{
lengthLengths[FixedAlphabet[i]] = (byte)_bitStream.ReadBitsLSB(3);
lengthLengths[BitLengthOrder[i]] = (byte)_bitStream.ReadBitsLSB(3);
}
for (int i = (int)numLength; i < 19; i++)
{
lengthLengths[FixedAlphabet[i]] = 0;
lengthLengths[BitLengthOrder[i]] = 0;
}
// Make the lengths tree
@@ -245,13 +246,13 @@ namespace SabreTools.Compression.MSZIP
else
{
sym -= 257;
uint? length = MatchLengths[sym] + _bitStream.ReadBitsLSB(MatchExtraBits[sym]);
uint? length = CopyLengths[sym] + _bitStream.ReadBitsLSB(LiteralExtraBits[sym]);
if (length == null)
return null;
int distanceCode = distanceTree.Decode(_bitStream);
uint? distance = DistanceLengths[distanceCode] + _bitStream.ReadBitsLSB(DistanceExtraBits[distanceCode]);
uint? distance = CopyOffsets[distanceCode] + _bitStream.ReadBitsLSB(DistanceExtraBits[distanceCode]);
if (distance == null)
return null;