diff --git a/src/ImageSharp/Formats/Jpeg/Components/Decoder/HuffmanScanBuffer.cs b/src/ImageSharp/Formats/Jpeg/Components/Decoder/HuffmanScanBuffer.cs
index 13c89c82c..cabd26dc6 100644
--- a/src/ImageSharp/Formats/Jpeg/Components/Decoder/HuffmanScanBuffer.cs
+++ b/src/ImageSharp/Formats/Jpeg/Components/Decoder/HuffmanScanBuffer.cs
@@ -85,8 +85,8 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder
{
// Attempt to load at least the minimum number of required bits into the buffer.
// We fail to do so only if we hit a marker or reach the end of the input stream.
- this.remainingBits += 48;
- this.data = (this.data << 48) | this.GetBytes();
+ this.remainingBits += JpegConstants.Huffman.MinBits;
+ this.data = (this.data << JpegConstants.Huffman.MinBits) | this.GetBytes();
}
[MethodImpl(InliningOptions.ShortMethod)]
diff --git a/src/ImageSharp/Formats/Jpeg/Components/Decoder/HuffmanTable.cs b/src/ImageSharp/Formats/Jpeg/Components/Decoder/HuffmanTable.cs
index 4685ba289..602593016 100644
--- a/src/ImageSharp/Formats/Jpeg/Components/Decoder/HuffmanTable.cs
+++ b/src/ImageSharp/Formats/Jpeg/Components/Decoder/HuffmanTable.cs
@@ -82,12 +82,12 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder
// Figure C.1: make table of Huffman code length for each symbol
int p = 0;
- for (int l = 1; l <= 16; l++)
+ for (int j = 1; j <= 16; j++)
{
- int i = this.Sizes[l];
+ int i = this.Sizes[j];
while (i-- != 0)
{
- huffSize[p++] = (char)l;
+ huffSize[p++] = (char)j;
}
}
@@ -111,20 +111,19 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder
// Figure F.15: generate decoding tables for bit-sequential decoding
p = 0;
- for (int l = 1; l <= 16; l++)
+ for (int j = 1; j <= 16; j++)
{
- if (this.Sizes[l] != 0)
+ if (this.Sizes[j] != 0)
{
- int offset = p - (int)huffCode[p];
- this.ValOffset[l] = offset;
- p += this.Sizes[l];
- this.MaxCode[l] = huffCode[p - 1]; // Maximum code of length l
- this.MaxCode[l] <<= 64 - l; // Left justify
- this.MaxCode[l] |= (1ul << (64 - l)) - 1;
+ this.ValOffset[j] = p - (int)huffCode[p];
+ p += this.Sizes[j];
+ this.MaxCode[j] = huffCode[p - 1]; // Maximum code of length l
+ this.MaxCode[j] <<= JpegConstants.Huffman.RegisterSize - j; // Left justify
+ this.MaxCode[j] |= (1ul << (JpegConstants.Huffman.RegisterSize - j)) - 1;
}
else
{
- this.MaxCode[l] = 0;
+ this.MaxCode[j] = 0;
}
}
@@ -142,11 +141,12 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder
p = 0;
for (int length = 1; length <= JpegConstants.Huffman.LookupBits; length++)
{
+ int jShift = JpegConstants.Huffman.LookupBits - length;
for (int i = 1; i <= this.Sizes[length]; i++, p++)
{
// length = current code's length, p = its index in huffCode[] & Values[].
// Generate left-justified code followed by all possible bit sequences
- int lookBits = (int)(huffCode[p] << (JpegConstants.Huffman.LookupBits - length));
+ int lookBits = (int)(huffCode[p] << jShift);
for (int ctr = 1 << (JpegConstants.Huffman.LookupBits - length); ctr > 0; ctr--)
{
this.LookaheadSize[lookBits] = (byte)length;
diff --git a/src/ImageSharp/Formats/Jpeg/JpegConstants.cs b/src/ImageSharp/Formats/Jpeg/JpegConstants.cs
index a39480e12..53f185f01 100644
--- a/src/ImageSharp/Formats/Jpeg/JpegConstants.cs
+++ b/src/ImageSharp/Formats/Jpeg/JpegConstants.cs
@@ -1,7 +1,8 @@
-// Copyright (c) Six Labors and contributors.
+// Copyright (c) Six Labors and contributors.
// Licensed under the Apache License, Version 2.0.
using System.Collections.Generic;
+using SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder;
namespace SixLabors.ImageSharp.Formats.Jpeg
{
@@ -249,6 +250,11 @@ namespace SixLabors.ImageSharp.Formats.Jpeg
///
public const int RegisterSize = 64;
+ ///
+ /// The minimum number of bits required by the .
+ ///
+ public const int MinBits = 48;
+
///
/// If the next Huffman code is no more than this number of bits, we can obtain its length
/// and the corresponding symbol directly from this tables.
@@ -266,4 +272,4 @@ namespace SixLabors.ImageSharp.Formats.Jpeg
public const int LookupSize = 1 << LookupBits;
}
}
-}
\ No newline at end of file
+}