/// <summary>
/// Computes the CRC32 checksum of a file using the file path.
/// The actual CRC32 algorithm is described in RFC 1952
/// (GZIP file format specification version 4.3), this is also
/// the specification for the algorithm used in java.util.zip.
/// </summary>
/// <param name="filePath">the physical path of the file on the ESS</param>
/// <returns>the string form of the calculated CRC32 checksum</returns>
public static string ComputeCRC32(string filePath)
{
CRC_1952 crc = new CRC_1952();
FileStream fs = null;
ulong csum = 0L;
try
{
fs = new FileStream(filePath, FileMode.Open, FileAccess.Read);
byte[] buf = new byte[512];
int byteCount = fs.Read(buf, 0, 512);
while (byteCount > 0)
{
csum = crc.updateCRC(csum, buf, byteCount);
byteCount = fs.Read(buf, 0, 512);
}
fs.Close();
return csum.ToString("X");
}
catch (IOException ex)
{
throw new IOException("Exception thrown computing CRC32 checksum using the file path", ex);
}
}
/// <summary>
/// Computes the CRC32 checksum of a file using the data array
/// The actual CRC32 algorithm is described in RFC 1952
/// (GZIP file format specification version 4.3), this is also
/// the specification for the algorithm used in java.util.zip.
/// </summary>
/// <param name="data">the array of data</param>
/// <returns>the string form of the calculated CRC32 checksum</returns>
public static string ComputeCRC32(byte [] data)
{
CRC_1952 crc = new CRC_1952();
ulong csum = 0L;
try
{
sbyte[] sdata = new sbyte[data.Length];
for (int i = 0; i < data.Length; i++)
sdata[i] = (sbyte)data[i];
csum = crc.updateCRC(csum, data,data.Length);
return csum.ToString("X");
}
catch (IOException ex)
{
throw new IOException("Exception thrown computing CRC32 checksum using the data array", ex);
}
}
