private const int MaxSectionSizeBuffer = 10; // the maximum size of 2 MC values
public void Write(BitWriter writer)
{
void WriteSection(byte[] data)
{
writer.StartCrcCalculation(initialValue: DwgHeaderVariables.InitialCrcValue);
writer.WriteShortBigEndian((short)(data.Length + 2)); // account for crc
writer.WriteBytes(data);
writer.WriteCrc(writeCrcAsMsb: true);
}
// write in sections, each section is at most 2032 bytes, stop writing if remaining space is less than 10
var sectionStart = writer.Position;
var lastHandle = 0;
var lastLocation = 0;
var ms = new MemoryStream();
var sectionWriter = new BitWriter(ms);
foreach (var kvp in _handleOffsets.OrderBy(k => k.Key))
{
var sectionSize = writer.Position - sectionStart;
if (sectionSize >= MaxSectionSize - MaxSectionSizeBuffer)
{
// flush section
var sectionBytes = sectionWriter.AsBytes();
WriteSection(sectionBytes);
ms.Dispose();
ms = new MemoryStream();
sectionWriter = new BitWriter(ms);
sectionStart = writer.Position;
}
// now write the values
var handleDiff = kvp.Key - lastHandle;
var locationDiff = kvp.Value - lastLocation;
sectionWriter.Write_MC(handleDiff);
sectionWriter.Write_MC(locationDiff);
lastHandle = kvp.Key;
lastLocation = kvp.Value;
}
// flush the final section
var finalBytes = sectionWriter.AsBytes();
if (finalBytes.Length > 0)
{
WriteSection(finalBytes);
}
ms.Dispose();
// always finish with an empty section
WriteSection(new byte[0]);
}