/// <inheritdoc/>
public byte[] Decompress(byte[] data, long start = 0, long count = -1, object decompressorSettings = null)
{
if (count == 0)
{
return(Array.Empty <byte>());
}
#region Проверка аргументов
#if CHECK_ARGS
if (data is null)
{
throw new ArgumentNullException(nameof(data));
}
if ((start < 0) || (start >= data.LongLength))
{
throw new ArgumentOutOfRangeException(nameof(start));
}
if ((start + count) > data.LongLength)
{
throw new ArgumentOutOfRangeException(nameof(count));
}
#endif
#endregion Проверка аргументов
#region Инициализация
var last = (count < 0) ? (data.LongLength) : (start + count);
var pos = start;
var settings = new SavegameCompressonSettings(data[start], data[start + 1]);
int size = data.LoadUInt16(start + 2, isLittleEndian: true);
var res = new MemoryStream();
#endregion Инициализация
#region аспаковка
for (var i = start; i < last; i++)
{
if (data[i] == settings.ControlCode)
{
if ((i + 2) >= last)
{
throw new IncompleteDataException();
}
var cnt = data[++i];
var val = data[++i];
for (var j = 0; j < cnt; j++)
{
res.WriteByte(val);
}
}
else
{
res.WriteByte(data[i]);
}
}
#endregion аспаковка
return(res.ToArray());
}
/// <summary>
/// <para>Записать упаковочную последовательность байт в поток</para>
/// </summary>
/// <param name="outStream">Целевой поток</param>
/// <param name="val">Значение</param>
/// <param name="count">Количество повторов</param>
/// <param name="settings">Параметры упаковки</param>
private static void WriteRLE(Stream outStream, byte val, int count, SavegameCompressonSettings settings)
{
if (count > 0)
{
if (val == settings.ControlCode)
{
WritePackedSequence(outStream, val, count, settings);
}
else if (count <= settings.MaxUnRLEValueCount)
{
for (var i = 0; i < count; i++)
{
outStream.WriteByte(val);
}
}
else
{
WritePackedSequence(outStream, val, count, settings);
}
}
}
/// <summary>
/// <para>Записать кодовую последовательность в поток</para>
/// </summary>
/// <param name="outStream">Целевой поток</param>
/// <param name="val">Значение</param>
/// <param name="count">Количество повторов</param>
/// <param name="settings">Параметры упаковки</param>
private static void WritePackedSequence(Stream outStream, byte val, int count, SavegameCompressonSettings settings)
{
if (count > 0)
{
while (count > byte.MaxValue)
{
outStream.WriteByte(settings.ControlCode);
outStream.WriteByte(byte.MaxValue);
outStream.WriteByte(val);
count -= byte.MaxValue;
}
outStream.WriteByte(settings.ControlCode);
outStream.WriteByte((byte)count);
outStream.WriteByte(val);
}
}
