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Zero/Tests/PartitionFileStorageTest/Compressor.cs

71 lines
2.1 KiB

2 years ago
namespace PartitionFileStorageTest
{
public static class Compressor
{
public static byte[] GetEncodedBytes(IEnumerable<ulong> list, ref ulong last)
{
byte[] segmentsBytes;
using (var memoryStream = new MemoryStream())
{
foreach (var current in list)
{
var value = current - last;
memoryStream.Write7BitEncodedULong(value);
last = current;
}
segmentsBytes = memoryStream.ToArray();
}
return segmentsBytes;
}
public static IEnumerable<ulong> DecodeBytesContent(byte[] bytes)
{
ulong last = 0;
using (var memoryStream = new MemoryStream(bytes))
{
while (memoryStream.Position != memoryStream.Length)
{
var value = memoryStream.Read7BitEncodedULong();
var current = last + value;
yield return current;
last = current;
}
}
}
public static void Write7BitEncodedULong(this MemoryStream writer, ulong value)
{
var first = true;
while (first || value > 0)
{
first = false;
var lower7bits = (byte)(value & 0x7f);
value >>= 7;
if (value > 0)
lower7bits |= 128;
writer.WriteByte(lower7bits);
}
}
public static ulong Read7BitEncodedULong(this MemoryStream reader)
{
if (reader == null)
throw new ArgumentNullException(nameof(reader));
var more = true;
ulong value = 0;
var shift = 0;
while (more)
{
ulong lower7bits = (byte)reader.ReadByte();
more = (lower7bits & 128) != 0;
value |= (lower7bits & 0x7f) << shift;
shift += 7;
}
return value;
}
}
}

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