/// <summary>
/// Extract a PI from the given position in a buffer and returns the position of next PI (eventually) inside this buffer.
/// Throws exceptions if the PI to extract is badly formated (size doesn't match PI,...)
/// </summary>
/// <param name="buffer"></param>
/// <param name="start"></param>
/// <param name="offset"></param>
/// <returns>A PI object if found, null otherwise</returns>
public static CPI ExtractPI(byte[] buffer, int start, out int offset)
{
// offset is at least the starting position
offset = start;
CPI cpi = null;
// do we have anough space for a PGI+LGI
if (CPI.PI_HEADER_SIZE <= buffer.Length - offset)
{
// we do... try to create a PI from the buffer
try
{
cpi = new CPI(buffer[offset], buffer[offset + CPI.PI_PI_SIZE]);
offset += CPI.PI_HEADER_SIZE;
cpi.SetDataBytes(buffer, offset);
// arrived here the PI has been created
offset += cpi.PILen;
}
catch (Exception ex)
{
CLog.AddException(MethodBase.GetCurrentMethod().Name, ex);
cpi = null;
}
}
return(cpi);
}
/// <summary>
/// Get a CPI by its PI value
/// </summary>
/// <param name="pi">PI value to look for</param>
/// <returns>The CPI if it exists, NULL otherwise</returns>
public CPI GetPI(PIs pi)
{
try
{
CPI cpi = new CPI(pis[(byte)pi]);
return(cpi);
}
catch (System.Exception) { return(null); }
}
/// <summary>
/// Search a specific PI and fetch it if found.
/// Throws exceptions if the PI to fetch is badly formated (size doesn't match PI,...)
/// </summary>
/// <param name="pi"></param>
/// <param name="buffer"></param>
/// <returns>A PI object if found, null otherwise</returns>
public static CPI SearchPI(byte pi, byte[] buffer)
{
CPI cpi = null;
int offset = 0;
bool fFound = false;
do
{
int start = offset;
// extract the current PI
cpi = ExtractPI(buffer, start, out offset);
if (null != cpi)
{
// a PI was found, is it the one we're looking for ?
fFound = cpi.PI == pi;
if (!fFound)
{
cpi = null;
}
}
}while (!fFound && buffer.Length > offset);
return(cpi);
}
