VAR/VAR.UrlCompressor
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ByteExtensions: Extract byte array manipulation methods from Base62.

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This commit is contained in:
Valeriano A.R.
2017-07-09 19:44:59 +02:00
parent d753a9fc3c
commit b969da80f2
3 changed files with 61 additions and 55 deletions
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83
VAR.UrlCompressor/Base62.cs
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@@ -7,33 +7,6 @@ namespace VAR.UrlCompressor
{
private static string Base62CodingSpace = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
private static bool ReadBit(byte[] bytes, int position, int offset)
{
if (offset < 0) { return false; }
int tempPos = position + offset;
int bytePosition = tempPos / 8;
int bitPosition = tempPos % 8;
if (bytePosition >= bytes.Length) { return false; }
return (bytes[bytePosition] & (0x01 << (7 - bitPosition))) > 0;
}
private static void WriteBit(byte[] bytes, int position, int offset, bool value)
{
if (offset < 0) { return; }
int tempPos = position + offset;
int bytePosition = tempPos / 8;
int bitPosition = tempPos % 8;
if (bytePosition >= bytes.Length) { return; }
if (value)
{
bytes[bytePosition] = (byte)(bytes[bytePosition] | (0x01 << (7 - bitPosition)));
}
else
{
bytes[bytePosition] = (byte)(bytes[bytePosition] & (0xffffffff - (0x1 << (7 - bitPosition))));
}
}
public static string Encode(byte[] original)
{
StringBuilder sb = new StringBuilder();
@@ -47,12 +20,12 @@ namespace VAR.UrlCompressor
{
pad = lenght - (bitPosition + 6);
}
bool bit0 = ReadBit(original, bitPosition, 0 + pad);
bool bit1 = ReadBit(original, bitPosition, 1 + pad);
bool bit2 = ReadBit(original, bitPosition, 2 + pad);
bool bit3 = ReadBit(original, bitPosition, 3 + pad);
bool bit4 = ReadBit(original, bitPosition, 4 + pad);
bool bit5 = ReadBit(original, bitPosition, 5 + pad);
bool bit0 = original.ReadBit(bitPosition, 0 + pad);
bool bit1 = original.ReadBit(bitPosition, 1 + pad);
bool bit2 = original.ReadBit(bitPosition, 2 + pad);
bool bit3 = original.ReadBit(bitPosition, 3 + pad);
bool bit4 = original.ReadBit(bitPosition, 4 + pad);
bool bit5 = original.ReadBit(bitPosition, 5 + pad);
if (bit0 == true && bit1 == true && bit2 == true && bit3 == true && bit4 == true)
{
@@ -87,42 +60,42 @@ namespace VAR.UrlCompressor
if (rest == 8) { throw new Exception("Extra symbol at end"); }
if ((charIdx >> rest) > 0) { throw new Exception("Invalid ending symbol"); }
int pad = 6 - rest;
WriteBit(bytes, bitPosition, 0 - pad, (charIdx & 0x20) > 0);
WriteBit(bytes, bitPosition, 1 - pad, (charIdx & 0x10) > 0);
WriteBit(bytes, bitPosition, 2 - pad, (charIdx & 0x08) > 0);
WriteBit(bytes, bitPosition, 3 - pad, (charIdx & 0x04) > 0);
WriteBit(bytes, bitPosition, 4 - pad, (charIdx & 0x02) > 0);
WriteBit(bytes, bitPosition, 5 - pad, (charIdx & 0x01) > 0);
bytes.WriteBit(bitPosition, 0 - pad, (charIdx & 0x20) > 0);
bytes.WriteBit(bitPosition, 1 - pad, (charIdx & 0x10) > 0);
bytes.WriteBit(bitPosition, 2 - pad, (charIdx & 0x08) > 0);
bytes.WriteBit(bitPosition, 3 - pad, (charIdx & 0x04) > 0);
bytes.WriteBit(bitPosition, 4 - pad, (charIdx & 0x02) > 0);
bytes.WriteBit(bitPosition, 5 - pad, (charIdx & 0x01) > 0);
break;
}
if (charIdx == 60)
{
WriteBit(bytes, bitPosition, 0, true);
WriteBit(bytes, bitPosition, 1, true);
WriteBit(bytes, bitPosition, 2, true);
WriteBit(bytes, bitPosition, 3, true);
WriteBit(bytes, bitPosition, 4, false);
bytes.WriteBit(bitPosition, 0, true);
bytes.WriteBit(bitPosition, 1, true);
bytes.WriteBit(bitPosition, 2, true);
bytes.WriteBit(bitPosition, 3, true);
bytes.WriteBit(bitPosition, 4, false);
bitPosition += 5;
}
else if (charIdx == 61)
{
WriteBit(bytes, bitPosition, 0, true);
WriteBit(bytes, bitPosition, 1, true);
WriteBit(bytes, bitPosition, 2, true);
WriteBit(bytes, bitPosition, 3, true);
WriteBit(bytes, bitPosition, 4, true);
bytes.WriteBit(bitPosition, 0, true);
bytes.WriteBit(bitPosition, 1, true);
bytes.WriteBit(bitPosition, 2, true);
bytes.WriteBit(bitPosition, 3, true);
bytes.WriteBit(bitPosition, 4, true);
bitPosition += 5;
}
else
{
WriteBit(bytes, bitPosition, 0, (charIdx & 0x20) > 0);
WriteBit(bytes, bitPosition, 1, (charIdx & 0x10) > 0);
WriteBit(bytes, bitPosition, 2, (charIdx & 0x08) > 0);
WriteBit(bytes, bitPosition, 3, (charIdx & 0x04) > 0);
WriteBit(bytes, bitPosition, 4, (charIdx & 0x02) > 0);
WriteBit(bytes, bitPosition, 5, (charIdx & 0x01) > 0);
bytes.WriteBit(bitPosition, 0, (charIdx & 0x20) > 0);
bytes.WriteBit(bitPosition, 1, (charIdx & 0x10) > 0);
bytes.WriteBit(bitPosition, 2, (charIdx & 0x08) > 0);
bytes.WriteBit(bitPosition, 3, (charIdx & 0x04) > 0);
bytes.WriteBit(bitPosition, 4, (charIdx & 0x02) > 0);
bytes.WriteBit(bitPosition, 5, (charIdx & 0x01) > 0);
bitPosition += 6;
}
}

32
VAR.UrlCompressor/ByteExtensions.cs Normal file
View File

@@ -0,0 +1,32 @@
namespace VAR.UrlCompressor
{
static class ByteExtensions
{
public static bool ReadBit(this byte[] bytes, int position, int offset)
{
if (offset < 0) { return false; }
int tempPos = position + offset;
int bytePosition = tempPos / 8;
int bitPosition = tempPos % 8;
if (bytePosition >= bytes.Length) { return false; }
return (bytes[bytePosition] & (0x01 << (7 - bitPosition))) > 0;
}
public static void WriteBit(this byte[] bytes, int position, int offset, bool value)
{
if (offset < 0) { return; }
int tempPos = position + offset;
int bytePosition = tempPos / 8;
int bitPosition = tempPos % 8;
if (bytePosition >= bytes.Length) { return; }
if (value)
{
bytes[bytePosition] = (byte)(bytes[bytePosition] | (0x01 << (7 - bitPosition)));
}
else
{
bytes[bytePosition] = (byte)(bytes[bytePosition] & (0xffffffff - (0x1 << (7 - bitPosition))));
}
}
}
}

1
VAR.UrlCompressor/VAR.UrlCompressor.csproj
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@@ -41,6 +41,7 @@
</ItemGroup>
<ItemGroup>
<Compile Include="Base62.cs" />
<Compile Include="ByteExtensions.cs" />
<Compile Include="Properties\AssemblyInfo.cs" />
<Compile Include="UrlCompressor.cs" />
</ItemGroup>