/// <summary>
/// Reads a record using the previous data available.
/// TPS uses a stupid ( prossesing costly ) method to save space. It copies data from the last record if possible
/// </summary>
/// <param name="previous"></param>
/// <param name="pageDataRandomAccess"></param>
public TPSRecord(ref TPSRecord previous, ref RandomAccess pageDataRandomAccess)
{
//the flag tells us what data we should be copying
_flags = pageDataRandomAccess.leByte();
if ((_flags & 0x80) != 0)
{
_recordLength = pageDataRandomAccess.leShort();
}
else
{
_recordLength = previous.RecordLength;
}
if ((_flags & 0x40) != 0)
{
_headerLength = pageDataRandomAccess.leShort();
}
else
{
_headerLength = previous.HeaderLength;
}
//The last part tells us how much actual record data we should copy
int copy = _flags & 0x3F;
_data = new byte[_recordLength];
try {
Buffer.BlockCopy(previous.RecordData, 0, _data, 0, copy);
Buffer.BlockCopy(pageDataRandomAccess.leBytes(_recordLength - copy), 0, _data, copy, (_recordLength - copy));
//We may have to check if we pulled enough bytes from the pageDataRA, incase we hit the end prematurely
} catch (Exception ex) {
throw new Exception("When reading " + (_recordLength - copy) + " bytes of TpsRecord");
}
//
buildHeader();
}
/// <summary>
/// Returns all records of the page
/// <returns></returns>
public List <TPSRecord> GetRecords()
{
List <TPSRecord> records = new List <TPSRecord>();
byte[] pageData = GetData();
//go through each record in the page
RandomAccess ra = new RandomAccess();
ra.OpenStream(new MemoryStream(pageData));
records.Clear();
// Skip pages with non 0x00 flags as they don't seem to contain TpsRecords.
if (flags == 0x00)
{
//data.pushPosition();
try {
TPSRecord prev = null;
do
{
TPSRecord current = null;
if (prev == null)
{
current = new TPSRecord(ref ra);
}
else
{
current = new TPSRecord(ref prev, ref ra);
}
records.Add(current);
prev = current;
} while (!ra.isAtEnd() && records.Count < recordCount);
} finally {
//data.popPosition();
}
}
return(records);
}
