public static byte[] Decode(byte[] src, int srcOff, int srcLen)
{
var len = VarInt.UvarInt(src, srcOff);
byte[] ret = new byte[len.Value];
Decode(src, srcOff, srcLen, ret, 0, ret.Length);
return(ret);
}
public static int Decode(byte[] source, int sourceOffset, int sourceLength, byte[] destination, int destinationOffset, int destinationLength)
{
// Get the uncompressed size
var len = VarInt.UvarInt(source, sourceOffset);
// Destination array doesn't have enough room for the decoded data.
if (destinationLength < (int)len.Value)
{
throw new IndexOutOfRangeException("snappy: destination array too short");
}
// Adjust the lengths
sourceLength += sourceOffset;
destinationLength += destinationOffset;
// Current offsets
int s = sourceOffset + len.VarIntLength;
int d = destinationOffset;
int offset = 0;
int length = 0;
while (s < sourceLength)
{
byte tag = (byte)(source[s] & 0x03);
if (tag == SnappyTag.Literal)
{
uint x = (uint)(source[s] >> 2);
if (x < 60)
{
s += 1;
}
else if (x == 60)
{
s += 2;
if (s > sourceLength)
{
throw new IndexOutOfRangeException("snappy: corrupt input");
}
x = (uint)source[s - 1];
}
else if (x == 61)
{
s += 3;
if (s > sourceLength)
{
throw new IndexOutOfRangeException("snappy: corrupt input");
}
x = (uint)source[s - 2] | (uint)source[s - 1] << 8;
}
else if (x == 62)
{
s += 4;
if (s > sourceLength)
{
throw new IndexOutOfRangeException("snappy: corrupt input");
}
x = (uint)source[s - 3] | (uint)source[s - 2] << 8 | (uint)source[s - 1] << 16;
}
else if (x == 63)
{
s += 5;
if (s > sourceLength)
{
throw new IndexOutOfRangeException("snappy: corrupt input");
}
x = (uint)source[s - 4] | (uint)source[s - 3] << 8 | (uint)source[s - 2] << 16 | (uint)source[s - 1] << 24;
}
length = (int)(x + 1);
if (length <= 0)
{
throw new IndexOutOfRangeException("snappy: unsupported literal length");
}
if (length > destinationLength - d || length > sourceOffset + sourceLength - s)
{
throw new IndexOutOfRangeException("snappy: corrupt input");
}
Array.Copy(source, s, destination, d, length);
d += length;
s += length;
continue;
}
else if (tag == SnappyTag.Copy1)
{
s += 2;
if (s > sourceOffset + sourceLength)
{
throw new IndexOutOfRangeException("snappy: corrupt input");
}
length = 4 + (((int)source[s - 2] >> 2) & 0x7);
offset = ((int)source[s - 2] & 0xe0) << 3 | (int)source[s - 1];
}
else if (tag == SnappyTag.Copy2)
{
s += 3;
if (s > sourceOffset + sourceLength)
{
throw new IndexOutOfRangeException("snappy: corrupt input");
}
length = 1 + ((int)source[s - 3] >> 2);
offset = (int)source[s - 2] | (int)source[s - 1] << 8;
}
else if (tag == SnappyTag.Copy4)
{
throw new NotSupportedException("snappy: unsupported COPY_4 tag");
}
int end = d + length;
if (offset > d || end > destinationLength)
{
throw new IndexOutOfRangeException("snappy: corrupt input");
}
for (; d < end; d++)
{
destination[d] = destination[d - offset];
}
}
return(d);
}
