public static IEnumerable <double> Pack(string infilePath, string outfilePath)
{
var file = new GamFile {
Infile = File.ReadAllBytes(infilePath)
};
foreach (var i in Pack(file))
{
yield return(i);
}
File.WriteAllBytes(outfilePath, file.Outfile);
}
private static IEnumerable <double> Pack(GamFile file)
{
var stream = new MemoryStream();
// Write GAM header and file size.
var header = AsciiEncoding.GetBytes("GAM\0");
stream.WriteAll(header);
var size = file.Infile.Length;
stream.WriteAll(LittleEndianBitConverter.GetBytes(size));
// Loop over file and compress it.
var read = 0;
var bitmask = new List <int>();
var bitmaskPosition = -1;
while (read < size)
{
yield return((float)read / size * 100);
if (bitmask.Count == 0)
{
// Create 2-byte placeholder for bitmask, remember its position.
bitmaskPosition = (int)stream.Tell();
stream.WriteAll(0, 0);
}
// Find best position in buffer to copy from, if such position exists.
var(bestPosition, bestLength) = Find(file.Infile, read);
if (bestPosition != null)
{
// Position found: write position and length to output.
var seek = (byte)(read - bestPosition.Value);
stream.WriteAll(seek, bestLength);
read += bestLength;
bitmask.Add(1);
}
else
{
// Can't copy from buffer, copy one byte from input to output.
stream.WriteAll(file.Infile[read]);
read += 1;
bitmask.Add(0);
}
if (bitmask.Count == 16 || read >= size)
{
// Bitmask is full: update placeholder for bitmask.
bitmask.Reverse();
var bitmaskShort = (short)bitmask.Aggregate((b, acc) => acc * 2 + b);
stream.Seek(bitmaskPosition, SeekOrigin.Begin);
stream.WriteAll(LittleEndianBitConverter.GetBytes(bitmaskShort));
stream.Seek(0, SeekOrigin.End);
bitmask.Clear();
}
}
file.Outfile = stream.ToArray();
stream.Close();
yield return(100.0);
}
