public static DwgObjectCache Parse(BitReader reader, DwgVersionId version) { var objectCache = new DwgObjectCache(version); var lastHandle = 0; var lastLocation = 0; reader.StartCrcCheck(); var sectionSize = reader.ReadShortBigEndian(); while (sectionSize != 2) { var sectionStart = reader.Offset; var sectionEnd = sectionStart + sectionSize - 2; while (reader.Offset < sectionEnd) { // read data var handleOffset = reader.Read_MC(allowNegation: false); var locationOffset = reader.Read_MC(); var handle = lastHandle + handleOffset; var location = lastLocation + locationOffset; objectCache._handleToOffset.Add(handle, location); lastHandle = handle; lastLocation = location; } reader.ValidateCrc(initialValue: DwgHeaderVariables.InitialCrcValue, readCrcAsMsb: true); reader.StartCrcCheck(); sectionSize = reader.ReadShortBigEndian(); } reader.ValidateCrc(initialValue: DwgHeaderVariables.InitialCrcValue, readCrcAsMsb: true); return(objectCache); }
internal static DwgHeaderVariables Parse(BitReader reader, DwgVersionId version) { var header = new DwgHeaderVariables(); reader.ValidateSentinel(StartSentinel); reader.StartCrcCheck(); var size = reader.Read_RL(); var startOffset = reader.Offset; header.ReadVariables(reader, version); reader.AlignToByte(); var unreadByteCount = Math.Max(startOffset + size - reader.Offset, 0); var unreadBytes = reader.ReadBytes(unreadByteCount); reader.ValidateCrc(initialValue: InitialCrcValue); reader.ValidateSentinel(EndSentinel); return(header); }
internal static IList <DwgClassDefinition> Parse(BitReader reader, DwgVersionId version) { reader.ValidateSentinel(StartSentinel); reader.StartCrcCheck(); var sectionSize = reader.Read_RL(); var dataStartOffset = reader.Offset; var dataEndOffset = dataStartOffset + sectionSize; var classes = new List <DwgClassDefinition>(); while (reader.Offset < dataEndOffset - 1) // may be in the middle of a byte { classes.Add(DwgClassDefinition.Parse(reader)); } reader.ValidateCrc(initialValue: DwgHeaderVariables.InitialCrcValue); reader.ValidateSentinel(EndSentinel); return(classes); }
internal static DwgFileHeader Parse(BitReader reader) { reader.StartCrcCheck(); var versionString = reader.ReadStringAscii(6); var version = DwgVersionIdExtensions.VersionIdFromString(versionString); var unknown1 = reader.ReadBytes(6); var maintVer = 0; if (version == DwgVersionId.R14) { maintVer = unknown1[5]; } var marker = reader.ReadByte(); if (marker != 1) { throw new DwgReadException("Expected value of 1 at offset 13."); } var imagePointer = reader.ReadInt(); var unknown2 = reader.ReadBytes(2); var codePage = reader.ReadShort(); var header = new DwgFileHeader(version, maintVer, imagePointer, codePage); var recordLocatorCount = reader.ReadInt(); for (int i = 0; i < recordLocatorCount; i++) { var locator = DwgSectionLocator.Parse(reader); switch (i) { case 0: header.HeaderVariablesLocator = locator; break; case 1: header.ClassSectionLocator = locator; break; case 2: header.ObjectMapLocator = locator; break; case 3: header.UnknownSection_R13C3AndLaterLocator = locator; break; case 4: header.UnknownSection_PaddingLocator = locator; break; } } ushort crcXorValue; switch (recordLocatorCount) { case 0: case 1: case 2: crcXorValue = 0; break; case 3: crcXorValue = 0xAD98; break; case 4: crcXorValue = 0x8101; break; case 5: crcXorValue = 0x3CC4; break; case 6: crcXorValue = 0x8461; break; default: throw new DwgReadException("Unsupported record locator count."); } reader.ValidateCrc(xorValue: crcXorValue); reader.ValidateSentinel(HeaderSentinel); return(header); }