| public Update ( byte buffer ) : void | ||
| buffer | byte | /// The source of the data to update with. /// |
| Результат | void | |
public static byte[] Compress(byte[] data)
{
if (data == null)
{
throw new ArgumentNullException("data");
}
using (var output = new MemoryStream())
{
// ZLib Header 0x78 0x9C
output.WriteByte(0x78);
output.WriteByte(0x9C);
using (var input = new MemoryStream(data))
{
using (var compressionStream = new DeflateStream(output, CompressionMode.Compress, true))
{
input.CopyTo(compressionStream);
compressionStream.Close();
// Adler32 hash of the uncompressed data
var adler32 = new Adler32();
adler32.Update(data);
byte[] hash = BitConverter.GetBytes((int) adler32.Value);
Array.Reverse(hash);
output.Write(hash, 0, hash.Length);
return output.ToArray();
}
}
}
}
private static void WriteDataChunksFast()
{
byte[] pixels = _image.ToByteArray();
// Convert the pixel array to a new array for adding
// the filter byte.
// --------------------------------------------------
byte[] data = new byte[_image.PixelWidth * _image.PixelHeight * 4 + _image.PixelHeight];
int rowLength = _image.PixelWidth * 4 + 1;
for (int y = 0; y < _image.PixelHeight; y++)
{
data[y * rowLength] = 0;
Array.Copy(pixels, y * _image.PixelWidth * 4, data, y * rowLength + 1, _image.PixelWidth * 4);
}
// --------------------------------------------------
Adler32 adler32 = new Adler32();
adler32.Update(data);
using (MemoryStream tempStream = new MemoryStream())
{
int remainder = data.Length;
int blockCount;
if ((data.Length % MaxBlockSize) == 0)
{
blockCount = data.Length / MaxBlockSize;
}
else
{
blockCount = (data.Length / MaxBlockSize) + 1;
}
// Write headers
tempStream.WriteByte(0x78);
tempStream.WriteByte(0xDA);
for (int i = 0; i < blockCount; i++)
{
// Write the length
ushort length = (ushort)((remainder < MaxBlockSize) ? remainder : MaxBlockSize);
if (length == remainder)
{
tempStream.WriteByte(0x01);
}
else
{
tempStream.WriteByte(0x00);
}
tempStream.Write(BitConverter.GetBytes(length), 0, 2);
// Write one's compliment of length
tempStream.Write(BitConverter.GetBytes((ushort)~length), 0, 2);
// Write blocks
tempStream.Write(data, (int)(i * MaxBlockSize), length);
// Next block
remainder -= MaxBlockSize;
}
WriteInteger(tempStream, (int)adler32.Value);
tempStream.Seek(0, SeekOrigin.Begin);
byte[] zipData = new byte[tempStream.Length];
tempStream.Read(zipData, 0, (int)tempStream.Length);
WriteChunk(PngChunkTypes.Data, zipData);
}
}
internal static void Run()
{
const int iterations = 0x20000;
const int testSize = 0x10000;
List<long> timeMurmur = new List<long>(iterations);
List<long> timeAdler = new List<long>(iterations);
List<long> timeMd5 = new List<long>(iterations);
byte[] randBytes = new byte[testSize];
var rnd = new Random();
var watchMurmur = new Stopwatch();
var watchAdler = new Stopwatch();
var watchMd5 = new Stopwatch();
bool dry = true;
DoRun:
for (int i = 0; i < iterations; i++)
{
rnd.NextBytes(randBytes);
{
var murmur = Murmur128.CreateMurmur();
watchMurmur.Restart();
murmur.ComputeHash(randBytes);
watchMurmur.Stop();
if (!dry)
timeMurmur.Add(watchMurmur.ElapsedTicks);
}
{
var adler = new Adler32();
watchAdler.Restart();
adler.Update(randBytes);
watchAdler.Stop();
if (!dry)
timeAdler.Add(watchAdler.ElapsedTicks);
}
{
var md5 = MD5.Create();
watchMd5.Restart();
md5.ComputeHash(randBytes);
watchMd5.Stop();
if (!dry)
timeMd5.Add(watchMd5.ElapsedTicks);
}
if (i == 0x1000 && dry)
{
dry = false;
goto DoRun;
}
}
var avgMurmur = TimeSpan.FromTicks(Convert.ToInt64(timeMurmur.Average()));
var avgAdler = TimeSpan.FromTicks(Convert.ToInt64(timeAdler.Average()));
var avgMd5 = TimeSpan.FromTicks(Convert.ToInt64(timeMd5.Average()));
Console.WriteLine("Average murmur:\t" + avgMurmur);
Console.WriteLine("Average adler:\t" + avgAdler);
Console.WriteLine("Average md5:\t" + avgMd5);
Console.ReadKey();
}
