private bool ParseLength(IByteSource source)
{
while (_parseStage == ParseStage.Length)
{
if (_tag == DicomTag.Item || _tag == DicomTag.ItemDelimitationItem ||
_tag == DicomTag.SequenceDelimitationItem)
{
if (!source.Require(4))
{
_result = DicomReaderResult.Suspended;
return(false);
}
_length = source.GetUInt32();
_parseStage = ParseStage.Value;
break;
}
if (_isExplicitVR || _badPrivateSequence)
{
if (_vr == DicomVR.Implicit)
{
if (!source.Require(4))
{
_result = DicomReaderResult.Suspended;
return(false);
}
_length = source.GetUInt32();
// assume that undefined length in implicit VR element is SQ
if (_length == _undefinedLength)
{
_vr = DicomVR.SQ;
}
}
else if (_vr.Is16bitLength)
{
if (!source.Require(2))
{
_result = DicomReaderResult.Suspended;
return(false);
}
_length = source.GetUInt16();
}
else
{
if (!source.Require(6))
{
_result = DicomReaderResult.Suspended;
return(false);
}
source.Skip(2);
_length = source.GetUInt32();
// CP-246 (#177) handling
// assume that Undefined Length in explicit datasets with VR UN are sequences
// According to CP-246 the sequence shall be handled as ILE, but this will be handled later...
// in the current code this needs to be restricted to privates
if (_length == _undefinedLength && _vr == DicomVR.UN && _tag.IsPrivate)
{
_vr = DicomVR.SQ;
}
}
}
else
{
if (!source.Require(4))
{
_result = DicomReaderResult.Suspended;
return(false);
}
_length = source.GetUInt32();
// assume that undefined length in implicit dataset is SQ
if (_length == _undefinedLength && _vr == DicomVR.UN)
{
_vr = DicomVR.SQ;
}
}
_parseStage = ParseStage.Value;
}
return(true);
}
private bool ParseItemSequenceTag(IByteSource source)
{
if (_parseStage == ParseStage.Tag)
{
source.Mark();
if (!source.Require(8))
{
_result = DicomReaderResult.Suspended;
return(false);
}
var group = source.GetUInt16();
var element = source.GetUInt16();
_tag = new DicomTag(@group, element);
if (_tag != DicomTag.Item && _tag != DicomTag.SequenceDelimitationItem)
{
// assume invalid sequence
source.Rewind();
if (!_implicit)
{
source.PopMilestone();
}
_observer.OnEndSequence();
// #565 Only reset the badPrivate sequence if we're in the correct depth
// This prevents prematurely resetting in case of sub-sequences contained in the bad private sequence
if (_badPrivateSequence && _sequenceDepth == _badPrivateSequenceDepth)
{
_isExplicitVR = !_isExplicitVR;
_badPrivateSequence = false;
}
return(false);
}
_length = source.GetUInt32();
if (_tag == DicomTag.SequenceDelimitationItem)
{
// #64, in case explicit length has been specified despite occurrence of Sequence Delimitation Item
if (source.HasReachedMilestone() && source.MilestonesCount > _sequenceDepth)
{
ResetState();
return(true);
}
// end of sequence
_observer.OnEndSequence();
// #565 Only reset the badPrivate sequence if we're in the correct depth
// This prevents prematurely resetting in case of sub-sequences contained in the bad private sequence
if (_badPrivateSequence && _sequenceDepth == _badPrivateSequenceDepth)
{
_isExplicitVR = !_isExplicitVR;
_badPrivateSequence = false;
}
ResetState();
return(false);
}
_parseStage = ParseStage.Value;
}
return(true);
}
private bool ParseItemSequenceTag(IByteSource source)
{
if (this.parseStage == ParseStage.Tag)
{
source.Mark();
if (!source.Require(8))
{
this.result = DicomReaderResult.Suspended;
return false;
}
var group = source.GetUInt16();
var element = source.GetUInt16();
this._tag = new DicomTag(@group, element);
if (this._tag != DicomTag.Item && this._tag != DicomTag.SequenceDelimitationItem)
{
// assume invalid sequence
source.Rewind();
if (!this._implicit)
{
source.PopMilestone();
}
this.observer.OnEndSequence();
if (this.badPrivateSequence)
{
this.isExplicitVR = !this.isExplicitVR;
this.badPrivateSequence = false;
}
return false;
}
this.length = source.GetUInt32();
if (this._tag == DicomTag.SequenceDelimitationItem)
{
// #64, in case explicit length has been specified despite occurrence of Sequence Delimitation Item
if (source.HasReachedMilestone() && source.MilestonesCount > this.sequenceDepth)
{
this.ResetState();
return true;
}
// end of sequence
this.observer.OnEndSequence();
if (this.badPrivateSequence)
{
this.isExplicitVR = !this.isExplicitVR;
this.badPrivateSequence = false;
}
this.ResetState();
return false;
}
this.parseStage = ParseStage.Value;
}
return true;
}
private bool ParseFragmentSequenceTag(IByteSource source)
{
if (this.parseStage == ParseStage.Tag)
{
source.Mark();
if (!source.Require(8))
{
this.result = DicomReaderResult.Suspended;
return false;
}
var group = source.GetUInt16();
var element = source.GetUInt16();
DicomTag tag = new DicomTag(@group, element);
if (tag != DicomTag.Item && tag != DicomTag.SequenceDelimitationItem)
{
throw new DicomReaderException("Unexpected tag in DICOM fragment sequence: {0}", tag);
}
this.length = source.GetUInt32();
if (tag == DicomTag.SequenceDelimitationItem)
{
// end of fragment
this.observer.OnEndFragmentSequence();
this.fragmentItem = 0;
this.ResetState();
return false;
}
this.fragmentItem++;
this.parseStage = ParseStage.Value;
}
return true;
}
private void ParseFragmentSequence(IByteSource source, object state) {
try {
_result = DicomReaderResult.Processing;
while (!source.IsEOF) {
if (_state == ParseState.Tag) {
source.Mark();
if (!source.Require(8, ParseFragmentSequence, state)) {
_result = DicomReaderResult.Suspended;
return;
}
ushort group = source.GetUInt16();
ushort element = source.GetUInt16();
DicomTag tag = new DicomTag(group, element);
if (tag != DicomTag.Item && tag != DicomTag.SequenceDelimitationItem)
throw new DicomReaderException("Unexpected tag in DICOM fragment sequence: {0}", tag);
_length = source.GetUInt32();
if (tag == DicomTag.SequenceDelimitationItem) {
// end of fragment
_observer.OnEndFragmentSequence();
_fragmentItem = 0;
ResetState();
ParseDataset(source, PopState());
return;
}
_fragmentItem++;
_state = ParseState.Value;
}
if (_state == ParseState.Value) {
if (!source.Require(_length, ParseFragmentSequence, state)) {
_result = DicomReaderResult.Suspended;
return;
}
IByteBuffer buffer = source.GetBuffer(_length);
if (_fragmentItem == 1)
buffer = EndianByteBuffer.Create(buffer, source.Endian, 4);
else
buffer = EndianByteBuffer.Create(buffer, source.Endian, _vr.UnitSize);
_observer.OnFragmentSequenceItem(source, buffer);
_state = ParseState.Tag;
}
}
} catch (Exception e) {
_exception = e;
_result = DicomReaderResult.Error;
} finally {
if (_result != DicomReaderResult.Processing && _result != DicomReaderResult.Suspended) {
_async.Set();
}
}
}
private void ParseDataset(IByteSource source, object state)
{
try {
_result = DicomReaderResult.Processing;
while (!source.IsEOF && !source.HasReachedMilestone())
{
if (_state == ParseState.Tag)
{
source.Mark();
if (!source.Require(4, ParseDataset, state))
{
_result = DicomReaderResult.Suspended;
return;
}
ushort group = source.GetUInt16();
ushort element = source.GetUInt16();
DicomPrivateCreator creator = null;
if (group.IsOdd() && element > 0x00ff)
{
string pvt = null;
uint card = (uint)(group << 16) + (uint)(element >> 8);
if (_private.TryGetValue(card, out pvt))
{
creator = Dictionary.GetPrivateCreator(pvt);
}
}
_tag = new DicomTag(group, element, creator);
if (_stop != null && _tag.CompareTo(_stop) >= 0)
{
_result = DicomReaderResult.Stopped;
return;
}
_state = ParseState.VR;
}
while (_state == ParseState.VR)
{
if (_tag == DicomTag.Item || _tag == DicomTag.ItemDelimitationItem || _tag == DicomTag.SequenceDelimitationItem)
{
_vr = DicomVR.NONE;
_state = ParseState.Length;
break;
}
if (IsExplicitVR)
{
if (!source.Require(2, ParseDataset, state))
{
_result = DicomReaderResult.Suspended;
return;
}
byte[] bytes = source.GetBytes(2);
string vr = Encoding.ASCII.GetString(bytes);
_vr = DicomVR.Parse(vr);
}
else
{
DicomDictionaryEntry entry = Dictionary[_tag];
if (entry != null)
{
if (entry.ValueRepresentations.Contains(DicomVR.OB) && entry.ValueRepresentations.Contains(DicomVR.OW))
{
_vr = DicomVR.OW; // ???
}
else
{
_vr = entry.ValueRepresentations.FirstOrDefault();
}
}
}
if (_vr == null)
{
_vr = DicomVR.UN;
}
_state = ParseState.Length;
if (_vr == DicomVR.UN)
{
if (_tag.Element == 0x0000)
{
// Group Length to UL
_vr = DicomVR.UL;
break;
}
if (_tag.Group.IsOdd())
{
if (_tag.Element <= 0x00ff)
{
// Private Creator to LO
_vr = DicomVR.LO;
break;
}
else if (IsExplicitVR)
{
DicomDictionaryEntry entry = Dictionary[_tag];
if (entry != null)
{
_vr = entry.ValueRepresentations.FirstOrDefault();
}
if (_vr == null)
{
_vr = DicomVR.UN;
}
break;
}
}
}
}
while (_state == ParseState.Length)
{
if (_tag == DicomTag.Item || _tag == DicomTag.ItemDelimitationItem || _tag == DicomTag.SequenceDelimitationItem)
{
if (!source.Require(4, ParseDataset, state))
{
_result = DicomReaderResult.Suspended;
return;
}
_length = source.GetUInt32();
_state = ParseState.Value;
break;
}
if (IsExplicitVR)
{
if (_vr.Is16bitLength)
{
if (!source.Require(2, ParseDataset, state))
{
_result = DicomReaderResult.Suspended;
return;
}
_length = source.GetUInt16();
}
else
{
if (!source.Require(6, ParseDataset, state))
{
_result = DicomReaderResult.Suspended;
return;
}
source.Skip(2);
_length = source.GetUInt32();
}
}
else
{
if (!source.Require(4, ParseDataset, state))
{
_result = DicomReaderResult.Suspended;
return;
}
_length = source.GetUInt32();
}
_state = ParseState.Value;
}
if (_state == ParseState.Value)
{
if (_tag == DicomTag.ItemDelimitationItem)
{
// end of sequence item
ParseItemSequence(source, state);
return;
}
if (_vr == DicomVR.SQ)
{
// start of sequence
_observer.OnBeginSequence(source, _tag, _length);
_state = ParseState.Tag;
if (_length != UndefinedLength)
{
source.PushMilestone(_length);
}
PushState(state);
ParseItemSequence(source, null);
continue;
}
if (_length == UndefinedLength)
{
_observer.OnBeginFragmentSequence(source, _tag, _vr);
_state = ParseState.Tag;
PushState(state);
ParseFragmentSequence(source, null);
continue;
}
if (!source.Require(_length, ParseDataset, state))
{
_result = DicomReaderResult.Suspended;
return;
}
IByteBuffer buffer = source.GetBuffer(_length);
if (!_vr.IsString)
{
buffer = EndianByteBuffer.Create(buffer, source.Endian, _vr.UnitSize);
}
_observer.OnElement(source, _tag, _vr, buffer);
ResetState();
}
}
if (source.HasReachedMilestone())
{
// end of explicit length sequence item
_observer.OnEndSequenceItem();
source.PopMilestone();
ParseItemSequence(source, state);
return;
}
// end of processing
_result = DicomReaderResult.Success;
} catch (Exception e) {
_exception = e;
_result = DicomReaderResult.Error;
} finally {
if (_result != DicomReaderResult.Processing && _result != DicomReaderResult.Suspended)
{
_async.Set();
}
}
}
private static void Preprocess(
IByteSource source,
ref DicomFileFormat fileFormat,
ref DicomTransferSyntax syntax)
{
// mark file origin
source.Mark();
// test for DICM preamble
source.Skip(128);
if (source.GetUInt8() == 'D' && source.GetUInt8() == 'I' && source.GetUInt8() == 'C'
&& source.GetUInt8() == 'M')
{
fileFormat = DicomFileFormat.DICOM3;
}
// test for incorrect syntax in file meta info
do
{
if (fileFormat == DicomFileFormat.DICOM3)
{
// move milestone to after preamble
source.Mark();
}
else
{
// rewind to origin milestone
source.Rewind();
}
// test for file meta info
var group = source.GetUInt16();
if (@group > 0x00ff)
{
source.Endian = Endian.Big;
syntax = DicomTransferSyntax.ExplicitVRBigEndian;
@group = Endian.Swap(@group);
}
if (@group > 0x00ff)
{
// invalid starting tag
fileFormat = DicomFileFormat.Unknown;
source.Rewind();
break;
}
if (fileFormat == DicomFileFormat.Unknown)
{
fileFormat = @group == 0x0002
? DicomFileFormat.DICOM3NoPreamble
: DicomFileFormat.DICOM3NoFileMetaInfo;
}
var element = source.GetUInt16();
var tag = new DicomTag(@group, element);
// test for explicit VR
var vrt = Encoding.UTF8.GetBytes(tag.DictionaryEntry.ValueRepresentations[0].Code);
var vrs = source.GetBytes(2);
if (vrt[0] != vrs[0] || vrt[1] != vrs[1])
{
// implicit VR
syntax = syntax.Endian == Endian.Little
? DicomTransferSyntax.ImplicitVRLittleEndian
: DicomTransferSyntax.ImplicitVRBigEndian;
}
source.Rewind();
}
while (fileFormat == DicomFileFormat.Unknown);
if (fileFormat == DicomFileFormat.Unknown)
{
throw new DicomReaderException("Attempted to read invalid DICOM file");
}
// Adopt transfer syntax endianess to byte source.
source.Endian = syntax.Endian;
}
private bool IsPrivateSequence(IByteSource source) {
source.Mark();
try {
var group = source.GetUInt16();
var element = source.GetUInt16();
var tag = new DicomTag(group, element);
if (tag == DicomTag.Item || tag == DicomTag.SequenceDelimitationItem)
return true;
} finally {
source.Rewind();
}
return false;
}
private void ParseFragmentSequence(IByteSource source, object state)
{
try {
_result = DicomReaderResult.Processing;
while (!source.IsEOF)
{
if (_state == ParseState.Tag)
{
source.Mark();
if (!source.Require(8, ParseFragmentSequence, state))
{
_result = DicomReaderResult.Suspended;
return;
}
ushort group = source.GetUInt16();
ushort element = source.GetUInt16();
DicomTag tag = new DicomTag(group, element);
if (tag != DicomTag.Item && tag != DicomTag.SequenceDelimitationItem)
{
throw new DicomReaderException("Unexpected tag in DICOM fragment sequence: {0}", tag);
}
_length = source.GetUInt32();
if (tag == DicomTag.SequenceDelimitationItem)
{
// end of fragment
_observer.OnEndFragmentSequence();
_fragmentItem = 0;
ResetState();
ParseDataset(source, PopState());
return;
}
_fragmentItem++;
_state = ParseState.Value;
}
if (_state == ParseState.Value)
{
if (!source.Require(_length, ParseFragmentSequence, state))
{
_result = DicomReaderResult.Suspended;
return;
}
IByteBuffer buffer = source.GetBuffer(_length);
if (_fragmentItem == 1)
{
buffer = EndianByteBuffer.Create(buffer, source.Endian, 4);
}
else
{
buffer = EndianByteBuffer.Create(buffer, source.Endian, _vr.UnitSize);
}
_observer.OnFragmentSequenceItem(source, buffer);
_state = ParseState.Tag;
}
}
} catch (Exception e) {
_exception = e;
_result = DicomReaderResult.Error;
} finally {
if (_result != DicomReaderResult.Processing && _result != DicomReaderResult.Suspended)
{
_async.Set();
}
}
}
private void ParseDataset(IByteSource source, object state)
{
try {
_result = DicomReaderResult.Processing;
while (!source.IsEOF && !source.HasReachedMilestone() && _result == DicomReaderResult.Processing)
{
if (_state == ParseState.Tag)
{
source.Mark();
if (!source.Require(4, ParseDataset, state))
{
_result = DicomReaderResult.Suspended;
return;
}
ushort group = source.GetUInt16();
ushort element = source.GetUInt16();
DicomPrivateCreator creator = null;
if (group.IsOdd() && element > 0x00ff)
{
string pvt = null;
uint card = (uint)(group << 16) + (uint)(element >> 8);
if (_private.TryGetValue(card, out pvt))
{
creator = Dictionary.GetPrivateCreator(pvt);
}
}
_tag = new DicomTag(group, element, creator);
if (_stop != null && _tag.CompareTo(_stop) >= 0)
{
_result = DicomReaderResult.Stopped;
return;
}
_state = ParseState.VR;
}
while (_state == ParseState.VR)
{
if (_tag == DicomTag.Item || _tag == DicomTag.ItemDelimitationItem || _tag == DicomTag.SequenceDelimitationItem)
{
_vr = DicomVR.NONE;
_state = ParseState.Length;
break;
}
if (IsExplicitVR)
{
if (!source.Require(2, ParseDataset, state))
{
_result = DicomReaderResult.Suspended;
return;
}
byte[] bytes = source.GetBytes(2);
string vr = Encoding.UTF8.GetString(bytes, 0, bytes.Length);
try {
_vr = DicomVR.Parse(vr);
} catch {
// unable to parse VR
_vr = DicomVR.UN;
}
}
else
{
DicomDictionaryEntry entry = Dictionary[_tag];
if (entry != null)
{
if (entry == DicomDictionary.UnknownTag)
{
_vr = DicomVR.UN;
}
else if (entry.ValueRepresentations.Contains(DicomVR.OB) && entry.ValueRepresentations.Contains(DicomVR.OW))
{
_vr = DicomVR.OW; // ???
}
else
{
_vr = entry.ValueRepresentations.FirstOrDefault();
}
}
}
if (_vr == null)
{
_vr = DicomVR.UN;
}
_state = ParseState.Length;
if (_vr == DicomVR.UN)
{
if (_tag.Element == 0x0000)
{
// Group Length to UL
_vr = DicomVR.UL;
break;
}
else if (IsExplicitVR)
{
break;
}
}
if (_tag.IsPrivate)
{
if (_tag.Element != 0x0000 && _tag.Element <= 0x00ff)
{
_vr = DicomVR.LO; // force private creator to LO
}
}
}
while (_state == ParseState.Length)
{
if (_tag == DicomTag.Item || _tag == DicomTag.ItemDelimitationItem || _tag == DicomTag.SequenceDelimitationItem)
{
if (!source.Require(4, ParseDataset, state))
{
_result = DicomReaderResult.Suspended;
return;
}
_length = source.GetUInt32();
_state = ParseState.Value;
break;
}
if (IsExplicitVR)
{
if (_vr.Is16bitLength)
{
if (!source.Require(2, ParseDataset, state))
{
_result = DicomReaderResult.Suspended;
return;
}
_length = source.GetUInt16();
}
else
{
if (!source.Require(6, ParseDataset, state))
{
_result = DicomReaderResult.Suspended;
return;
}
source.Skip(2);
_length = source.GetUInt32();
}
}
else
{
if (!source.Require(4, ParseDataset, state))
{
_result = DicomReaderResult.Suspended;
return;
}
_length = source.GetUInt32();
// assume that undefined length in implicit dataset is SQ
if (_length == UndefinedLength && _vr == DicomVR.UN)
{
_vr = DicomVR.SQ;
}
}
_state = ParseState.Value;
}
if (_state == ParseState.Value)
{
// check dictionary for VR after reading length to handle 16-bit lengths
// check before reading value to handle SQ elements
if (_vr == DicomVR.UN && IsExplicitVR)
{
var entry = Dictionary[_tag];
if (entry != null)
{
_vr = entry.ValueRepresentations.FirstOrDefault();
}
if (_vr == null)
{
_vr = DicomVR.UN;
}
}
if (_tag == DicomTag.ItemDelimitationItem)
{
// end of sequence item
return;
}
while (_vr == DicomVR.SQ && _tag.IsPrivate)
{
if (!IsPrivateSequence(source))
{
_vr = DicomVR.UN;
break;
}
if (IsPrivateSequenceBad(source))
{
_badPrivateSequence = true;
_explicit = !_explicit;
}
break;
}
if (_vr == DicomVR.SQ)
{
// start of sequence
_observer.OnBeginSequence(source, _tag, _length);
_state = ParseState.Tag;
if (_length != UndefinedLength)
{
_implicit = false;
source.PushMilestone(_length);
}
else
{
_implicit = true;
}
PushState(state);
ParseItemSequence(source, null);
continue;
}
if (_length == UndefinedLength)
{
_observer.OnBeginFragmentSequence(source, _tag, _vr);
_state = ParseState.Tag;
PushState(state);
ParseFragmentSequence(source, null);
continue;
}
if (!source.Require(_length, ParseDataset, state))
{
_result = DicomReaderResult.Suspended;
return;
}
IByteBuffer buffer = source.GetBuffer(_length);
if (!_vr.IsString)
{
buffer = EndianByteBuffer.Create(buffer, source.Endian, _vr.UnitSize);
}
_observer.OnElement(source, _tag, _vr, buffer);
// parse private creator value and add to lookup table
if (_tag.IsPrivate && _tag.Element != 0x0000 && _tag.Element <= 0x00ff)
{
var creator = DicomEncoding.Default.GetString(buffer.Data, 0, buffer.Data.Length).TrimEnd((char)DicomVR.LO.PaddingValue);
var card = (uint)(_tag.Group << 16) + (uint)(_tag.Element);
_private[card] = creator;
}
ResetState();
}
}
if (source.HasReachedMilestone())
{
// end of explicit length sequence item
source.PopMilestone();
return;
}
if (_result != DicomReaderResult.Processing)
{
return;
}
// end of processing
_result = DicomReaderResult.Success;
} catch (Exception e) {
_exception = e;
_result = DicomReaderResult.Error;
} finally {
if (_result != DicomReaderResult.Processing && _result != DicomReaderResult.Suspended)
{
_async.Set();
}
}
}
private void ParseItemSequence(IByteSource source, object state)
{
try {
_result = DicomReaderResult.Processing;
while (!source.IsEOF && !source.HasReachedMilestone())
{
if (_state == ParseState.Tag)
{
source.Mark();
if (!source.Require(8, ParseItemSequence, state))
{
_result = DicomReaderResult.Suspended;
return;
}
ushort group = source.GetUInt16();
ushort element = source.GetUInt16();
_tag = new DicomTag(group, element);
if (_tag != DicomTag.Item && _tag != DicomTag.SequenceDelimitationItem)
{
// assume invalid sequence
source.Rewind();
if (!_implicit)
{
source.PopMilestone();
}
_observer.OnEndSequence();
if (_badPrivateSequence)
{
_explicit = !_explicit;
_badPrivateSequence = false;
}
return;
}
_length = source.GetUInt32();
if (_tag == DicomTag.SequenceDelimitationItem)
{
// end of sequence
_observer.OnEndSequence();
if (_badPrivateSequence)
{
_explicit = !_explicit;
_badPrivateSequence = false;
}
ResetState();
return;
}
_state = ParseState.Value;
}
if (_state == ParseState.Value)
{
if (_length != UndefinedLength)
{
if (!source.Require(_length, ParseItemSequence, state))
{
_result = DicomReaderResult.Suspended;
return;
}
source.PushMilestone(_length);
}
_observer.OnBeginSequenceItem(source, _length);
ResetState();
ParseDataset(source, state);
ResetState();
_observer.OnEndSequenceItem();
continue;
}
}
// end of explicit length sequence
if (source.HasReachedMilestone())
{
source.PopMilestone();
}
_observer.OnEndSequence();
if (_badPrivateSequence)
{
_explicit = !_explicit;
_badPrivateSequence = false;
}
} catch (Exception e) {
_exception = e;
_result = DicomReaderResult.Error;
} finally {
if (_result != DicomReaderResult.Processing && _result != DicomReaderResult.Suspended)
{
_async.Set();
}
}
}
private void ParsePreamble(IByteSource source, object state)
{
try {
if (!source.Require(132, ParsePreamble, state))
{
return;
}
// mark file origin
_source.Mark();
// test for DICM preamble
_source.Skip(128);
if (_source.GetUInt8() == 'D' &&
_source.GetUInt8() == 'I' &&
_source.GetUInt8() == 'C' &&
_source.GetUInt8() == 'M')
{
_fileFormat = DicomFileFormat.DICOM3;
}
// test for incorrect syntax in file meta info
do
{
if (_fileFormat == DicomFileFormat.DICOM3)
{
// move milestone to after preamble
_source.Mark();
}
else
{
// rewind to origin milestone
_source.Rewind();
}
// test for file meta info
var group = _source.GetUInt16();
if (group > 0x00ff)
{
_source.Endian = Endian.Big;
_syntax = DicomTransferSyntax.ExplicitVRBigEndian;
group = Endian.Swap(group);
}
if (group > 0x00ff)
{
// invalid starting tag
_fileFormat = DicomFileFormat.Unknown;
_source.Rewind();
break;
}
if (_fileFormat == DicomFileFormat.Unknown)
{
if (group == 0x0002)
{
_fileFormat = DicomFileFormat.DICOM3NoPreamble;
}
else
{
_fileFormat = DicomFileFormat.DICOM3NoFileMetaInfo;
}
}
var element = _source.GetUInt16();
var tag = new DicomTag(group, element);
// test for explicit VR
var vrt = Encoding.ASCII.GetBytes(tag.DictionaryEntry.ValueRepresentations[0].Code);
var vrs = _source.GetBytes(2);
if (vrt[0] != vrs[0] || vrt[1] != vrs[1])
{
// implicit VR
if (_syntax.Endian == Endian.Little)
{
_syntax = DicomTransferSyntax.ImplicitVRLittleEndian;
}
else
{
_syntax = DicomTransferSyntax.ImplicitVRBigEndian;
}
}
_source.Rewind();
} while (_fileFormat == DicomFileFormat.Unknown);
if (_fileFormat == DicomFileFormat.Unknown)
{
throw new DicomReaderException("Attempted to read invalid DICOM file");
}
var obs = new DicomReaderCallbackObserver();
if (_fileFormat != DicomFileFormat.DICOM3)
{
obs.Add(DicomTag.RecognitionCodeRETIRED, (object sender, DicomReaderEventArgs ea) => {
try {
string code = Encoding.ASCII.GetString(ea.Data.Data);
if (code == "ACR-NEMA 1.0")
{
_fileFormat = DicomFileFormat.ACRNEMA1;
}
else if (code == "ACR-NEMA 2.0")
{
_fileFormat = DicomFileFormat.ACRNEMA2;
}
} catch {
}
});
}
obs.Add(DicomTag.TransferSyntaxUID, (object sender, DicomReaderEventArgs ea) => {
try {
string uid = Encoding.ASCII.GetString(ea.Data.Data);
_syntax = DicomTransferSyntax.Parse(uid);
} catch {
}
});
_source.Endian = _syntax.Endian;
_reader.IsExplicitVR = _syntax.IsExplicitVR;
if (_fileFormat == DicomFileFormat.DICOM3NoFileMetaInfo)
{
_reader.BeginRead(_source, new DicomReaderMultiObserver(obs, _dataObserver), null, OnDatasetParseComplete, null);
}
else
{
_reader.BeginRead(_source, new DicomReaderMultiObserver(obs, _fmiObserver), FileMetaInfoStopTag, OnFileMetaInfoParseComplete, null);
}
} catch (Exception e) {
if (_exception == null)
{
_exception = e;
}
_result = DicomReaderResult.Error;
} finally {
if (_result != DicomReaderResult.Processing && _result != DicomReaderResult.Suspended)
{
_async.Set();
}
}
}
private static bool IsPrivateSequenceBad(IByteSource source, bool isExplicitVR)
{
source.Mark();
try
{
// Skip "item" tags; continue skipping until length is non-zero (#223)
while (new DicomTag(source.GetUInt16(), source.GetUInt16()) == DicomTag.Item // group, element
& source.GetUInt32() == 0) // length (using & instead of && enforces RHS to be evaluated regardless of LHS)
{
}
source.GetUInt16(); // group
source.GetUInt16(); // element
var bytes = source.GetBytes(2);
var vr = Encoding.UTF8.GetString(bytes, 0, bytes.Length);
DicomVR dummy;
if (DicomVR.TryParse(vr, out dummy)) return !isExplicitVR;
// unable to parse VR
if (isExplicitVR) return true;
}
finally
{
source.Rewind();
}
return false;
}
private static void Preprocess(
IByteSource source,
ref DicomFileFormat fileFormat,
ref DicomTransferSyntax syntax)
{
// mark file origin
source.Mark();
// test for DICM preamble
source.Skip(128);
if (source.GetUInt8() == 'D' && source.GetUInt8() == 'I' && source.GetUInt8() == 'C' &&
source.GetUInt8() == 'M')
{
fileFormat = DicomFileFormat.DICOM3;
}
// test for incorrect syntax in file meta info
do
{
if (fileFormat == DicomFileFormat.DICOM3)
{
// move milestone to after preamble
source.Mark();
}
else
{
// rewind to origin milestone
source.Rewind();
}
// test for file meta info
var group = source.GetUInt16();
if (@group > 0x00ff)
{
source.Endian = Endian.Big;
syntax = DicomTransferSyntax.ExplicitVRBigEndian;
@group = Endian.Swap(@group);
}
if (@group > 0x00ff)
{
// invalid starting tag
fileFormat = DicomFileFormat.Unknown;
source.Rewind();
break;
}
if (fileFormat == DicomFileFormat.Unknown)
{
fileFormat = @group == 0x0002
? DicomFileFormat.DICOM3NoPreamble
: DicomFileFormat.DICOM3NoFileMetaInfo;
}
var element = source.GetUInt16();
var tag = new DicomTag(@group, element);
// test for explicit VR
var vrt = Encoding.UTF8.GetBytes(tag.DictionaryEntry.ValueRepresentations[0].Code);
var vrs = source.GetBytes(2);
if (vrt[0] != vrs[0] || vrt[1] != vrs[1])
{
// implicit VR
syntax = syntax.Endian == Endian.Little
? DicomTransferSyntax.ImplicitVRLittleEndian
: DicomTransferSyntax.ImplicitVRBigEndian;
}
source.Rewind();
}while (fileFormat == DicomFileFormat.Unknown);
if (fileFormat == DicomFileFormat.Unknown)
{
throw new DicomReaderException("Attempted to read invalid DICOM file");
}
// Adopt transfer syntax endianess to byte source.
source.Endian = syntax.Endian;
}
private static bool IsPrivateSequenceBad(IByteSource source, bool isExplicitVR)
{
source.Mark();
try
{
source.GetUInt16(); // group
source.GetUInt16(); // element
source.GetUInt32(); // length
source.GetUInt16(); // group
source.GetUInt16(); // element
var bytes = source.GetBytes(2);
var vr = Encoding.UTF8.GetString(bytes, 0, bytes.Length);
DicomVR dummy;
if (DicomVR.TryParse(vr, out dummy)) return !isExplicitVR;
// unable to parse VR
if (isExplicitVR) return true;
}
finally
{
source.Rewind();
}
return false;
}
private void ParseItemSequence(IByteSource source, object state) {
try {
_result = DicomReaderResult.Processing;
while (!source.IsEOF && !source.HasReachedMilestone()) {
if (_state == ParseState.Tag) {
source.Mark();
if (!source.Require(8, ParseItemSequence, state)) {
_result = DicomReaderResult.Suspended;
return;
}
ushort group = source.GetUInt16();
ushort element = source.GetUInt16();
_tag = new DicomTag(group, element);
if (_tag != DicomTag.Item && _tag != DicomTag.SequenceDelimitationItem) {
// assume invalid sequence
source.Rewind();
if (!_implicit)
source.PopMilestone();
_observer.OnEndSequence();
if (_badPrivateSequence) {
_explicit = !_explicit;
_badPrivateSequence = false;
}
return;
}
_length = source.GetUInt32();
if (_tag == DicomTag.SequenceDelimitationItem) {
// end of sequence
_observer.OnEndSequence();
if (_badPrivateSequence) {
_explicit = !_explicit;
_badPrivateSequence = false;
}
ResetState();
return;
}
_state = ParseState.Value;
}
if (_state == ParseState.Value) {
if (_length != UndefinedLength) {
if (!source.Require(_length, ParseItemSequence, state)) {
_result = DicomReaderResult.Suspended;
return;
}
source.PushMilestone(_length);
}
_observer.OnBeginSequenceItem(source, _length);
ResetState();
ParseDataset(source, state);
ResetState();
_observer.OnEndSequenceItem();
continue;
}
}
// end of explicit length sequence
if (source.HasReachedMilestone())
source.PopMilestone();
_observer.OnEndSequence();
if (_badPrivateSequence) {
_explicit = !_explicit;
_badPrivateSequence = false;
}
} catch (Exception e) {
_exception = e;
_result = DicomReaderResult.Error;
} finally {
if (_result != DicomReaderResult.Processing && _result != DicomReaderResult.Suspended) {
_async.Set();
}
}
}
private bool ParseTag(IByteSource source)
{
if (this.parseStage == ParseStage.Tag)
{
source.Mark();
if (!source.Require(4))
{
this.result = DicomReaderResult.Suspended;
return false;
}
var group = source.GetUInt16();
var element = source.GetUInt16();
DicomPrivateCreator creator = null;
if (@group.IsOdd() && element > 0x00ff)
{
var card = (uint)(@group << 16) + (uint)(element >> 8);
lock (this.locker)
{
string pvt;
if (this._private.TryGetValue(card, out pvt))
{
creator = this.dictionary.GetPrivateCreator(pvt);
}
}
}
this._tag = new DicomTag(@group, element, creator);
this._entry = this.dictionary[this._tag];
if (!this._tag.IsPrivate && this._entry != null && this._entry.MaskTag == null)
{
this._tag = this._entry.Tag; // Use dictionary tag
}
if (this.stop != null
&& this.stop(new ParseState { Tag = this._tag, SequenceDepth = this.sequenceDepth }))
{
this.result = DicomReaderResult.Stopped;
return false;
}
this.parseStage = ParseStage.VR;
}
return true;
}
private bool IsPrivateSequenceBad(IByteSource source) {
source.Mark();
try {
var group = source.GetUInt16();
var element = source.GetUInt16();
var tag = new DicomTag(group, element);
var length = source.GetUInt32();
group = source.GetUInt16();
element = source.GetUInt16();
tag = new DicomTag(group, element);
byte[] bytes = source.GetBytes(2);
string vr = Encoding.UTF8.GetString(bytes, 0, bytes.Length);
try {
DicomVR.Parse(vr);
return !_explicit;
} catch {
// unable to parse VR
if (_explicit)
return true;
}
} finally {
source.Rewind();
}
return false;
}
private bool ParseLength(IByteSource source)
{
while (this.parseStage == ParseStage.Length)
{
if (this._tag == DicomTag.Item || this._tag == DicomTag.ItemDelimitationItem
|| this._tag == DicomTag.SequenceDelimitationItem)
{
if (!source.Require(4))
{
this.result = DicomReaderResult.Suspended;
return false;
}
this.length = source.GetUInt32();
this.parseStage = ParseStage.Value;
break;
}
if (this.isExplicitVR)
{
if (this._vr == DicomVR.Implicit)
{
if (!source.Require(4))
{
this.result = DicomReaderResult.Suspended;
return false;
}
this.length = source.GetUInt32();
// assume that undefined length in implicit VR element is SQ
if (this.length == UndefinedLength)
{
this._vr = DicomVR.SQ;
}
}
else if (this._vr.Is16bitLength)
{
if (!source.Require(2))
{
this.result = DicomReaderResult.Suspended;
return false;
}
this.length = source.GetUInt16();
}
else
{
if (!source.Require(6))
{
this.result = DicomReaderResult.Suspended;
return false;
}
source.Skip(2);
this.length = source.GetUInt32();
// CP-246 (#177) handling
// assume that Undefined Length in explicit datasets with VR UN are sequences
// According to CP-246 the sequence shall be handled as ILE, but this will be handled later...
// in the current code this needs to be restricted to privates
if (this.length == UndefinedLength && this._vr == DicomVR.UN && this._tag.IsPrivate)
{
this._vr = DicomVR.SQ;
}
}
}
else
{
if (!source.Require(4))
{
this.result = DicomReaderResult.Suspended;
return false;
}
this.length = source.GetUInt32();
// assume that undefined length in implicit dataset is SQ
if (this.length == UndefinedLength && this._vr == DicomVR.UN)
{
this._vr = DicomVR.SQ;
}
}
this.parseStage = ParseStage.Value;
}
return true;
}
private void ParseDataset(IByteSource source, object state) {
try {
_result = DicomReaderResult.Processing;
while (!source.IsEOF && !source.HasReachedMilestone() && _result == DicomReaderResult.Processing) {
if (_state == ParseState.Tag) {
source.Mark();
if (!source.Require(4, ParseDataset, state)) {
_result = DicomReaderResult.Suspended;
return;
}
ushort group = source.GetUInt16();
ushort element = source.GetUInt16();
DicomPrivateCreator creator = null;
if (group.IsOdd() && element > 0x00ff) {
string pvt = null;
uint card = (uint)(group << 16) + (uint)(element >> 8);
if (_private.TryGetValue(card, out pvt))
creator = Dictionary.GetPrivateCreator(pvt);
}
_tag = new DicomTag(group, element, creator);
if (_stop != null && _tag.CompareTo(_stop) >= 0) {
_result = DicomReaderResult.Stopped;
return;
}
_state = ParseState.VR;
}
while (_state == ParseState.VR) {
if (_tag == DicomTag.Item || _tag == DicomTag.ItemDelimitationItem || _tag == DicomTag.SequenceDelimitationItem) {
_vr = DicomVR.NONE;
_state = ParseState.Length;
break;
}
if (IsExplicitVR) {
if (!source.Require(2, ParseDataset, state)) {
_result = DicomReaderResult.Suspended;
return;
}
byte[] bytes = source.GetBytes(2);
string vr = Encoding.UTF8.GetString(bytes, 0, bytes.Length);
try {
_vr = DicomVR.Parse(vr);
} catch {
// unable to parse VR
_vr = DicomVR.UN;
}
} else {
DicomDictionaryEntry entry = Dictionary[_tag];
if (entry != null) {
if (entry == DicomDictionary.UnknownTag)
_vr = DicomVR.UN;
else if (entry.ValueRepresentations.Contains(DicomVR.OB) && entry.ValueRepresentations.Contains(DicomVR.OW))
_vr = DicomVR.OW; // ???
else
_vr = entry.ValueRepresentations.FirstOrDefault();
}
}
if (_vr == null)
_vr = DicomVR.UN;
_state = ParseState.Length;
if (_vr == DicomVR.UN) {
if (_tag.Element == 0x0000) {
// Group Length to UL
_vr = DicomVR.UL;
break;
} else if (IsExplicitVR) {
break;
}
}
if (_tag.IsPrivate) {
if (_tag.Element != 0x0000 && _tag.Element <= 0x00ff && _vr == DicomVR.UN)
_vr = DicomVR.LO; // force private creator to LO
}
}
while (_state == ParseState.Length) {
if (_tag == DicomTag.Item || _tag == DicomTag.ItemDelimitationItem || _tag == DicomTag.SequenceDelimitationItem) {
if (!source.Require(4, ParseDataset, state)) {
_result = DicomReaderResult.Suspended;
return;
}
_length = source.GetUInt32();
_state = ParseState.Value;
break;
}
if (IsExplicitVR) {
if (_vr.Is16bitLength) {
if (!source.Require(2, ParseDataset, state)) {
_result = DicomReaderResult.Suspended;
return;
}
_length = source.GetUInt16();
} else {
if (!source.Require(6, ParseDataset, state)) {
_result = DicomReaderResult.Suspended;
return;
}
source.Skip(2);
_length = source.GetUInt32();
}
} else {
if (!source.Require(4, ParseDataset, state)) {
_result = DicomReaderResult.Suspended;
return;
}
_length = source.GetUInt32();
// assume that undefined length in implicit dataset is SQ
if (_length == UndefinedLength && _vr == DicomVR.UN)
_vr = DicomVR.SQ;
}
_state = ParseState.Value;
}
if (_state == ParseState.Value) {
// check dictionary for VR after reading length to handle 16-bit lengths
// check before reading value to handle SQ elements
if (_vr == DicomVR.UN && IsExplicitVR) {
var entry = Dictionary[_tag];
if (entry != null)
_vr = entry.ValueRepresentations.FirstOrDefault();
if (_vr == null)
_vr = DicomVR.UN;
}
if (_tag == DicomTag.ItemDelimitationItem) {
// end of sequence item
return;
}
while (_vr == DicomVR.SQ && _tag.IsPrivate) {
if (!IsPrivateSequence(source)) {
_vr = DicomVR.UN;
break;
}
if (IsPrivateSequenceBad(source)) {
_badPrivateSequence = true;
_explicit = !_explicit;
}
break;
}
if (_vr == DicomVR.SQ) {
// start of sequence
_observer.OnBeginSequence(source, _tag, _length);
_state = ParseState.Tag;
if (_length != UndefinedLength) {
_implicit = false;
source.PushMilestone(_length);
} else
_implicit = true;
PushState(state);
ParseItemSequence(source, null);
continue;
}
if (_length == UndefinedLength) {
_observer.OnBeginFragmentSequence(source, _tag, _vr);
_state = ParseState.Tag;
PushState(state);
ParseFragmentSequence(source, null);
continue;
}
if (!source.Require(_length, ParseDataset, state)) {
_result = DicomReaderResult.Suspended;
return;
}
IByteBuffer buffer = source.GetBuffer(_length);
if (!_vr.IsString)
buffer = EndianByteBuffer.Create(buffer, source.Endian, _vr.UnitSize);
_observer.OnElement(source, _tag, _vr, buffer);
// parse private creator value and add to lookup table
if (_tag.IsPrivate && _tag.Element != 0x0000 && _tag.Element <= 0x00ff) {
var creator = DicomEncoding.Default.GetString(buffer.Data, 0, buffer.Data.Length).TrimEnd((char)DicomVR.LO.PaddingValue);
var card = (uint)(_tag.Group << 16) + (uint)(_tag.Element);
_private[card] = creator;
}
ResetState();
}
}
if (source.HasReachedMilestone()) {
// end of explicit length sequence item
source.PopMilestone();
return;
}
if (_result != DicomReaderResult.Processing)
return;
// end of processing
_result = DicomReaderResult.Success;
} catch (Exception e) {
_exception = e;
_result = DicomReaderResult.Error;
} finally {
if (_result != DicomReaderResult.Processing && _result != DicomReaderResult.Suspended) {
_async.Set();
}
}
}
private void autoCheckTransferSyntax(IByteSource source, ushort group, ushort element, object state)
{
//start checking Transfer Syntax after reading premable bytes
if (group > 0x0002 && !bAutoDetectVRType)
{
bAutoDetectVRType = true;//just check once
source.Mark();//mark the original position of pointer
//try to parse VR
uint tmpLength = 0;
source.Skip(2);
if (!source.Require(2, ParseDataset, state))
{
_result = DicomReaderResult.Suspended;
source.Rewind();
return;
}
tmpLength = source.GetUInt16();
try
{
if (!source.Require(tmpLength, ParseDataset, state))
{
_result = DicomReaderResult.Suspended;
source.Rewind();
return;
}
source.Skip((int)tmpLength);
if (!source.Require(4, ParseDataset, state))
{
_result = DicomReaderResult.Suspended;
source.Rewind();
return;
}
ushort group2 = source.GetUInt16();
ushort element2 = source.GetUInt16();
DicomPrivateCreator creator2 = null;
if (group2.IsOdd() && element2 > 0x00ff)
{
string pvt2 = null;
uint card2 = (uint)(group2 << 16) + (uint)(element2 >> 8);
if (_private.TryGetValue(card2, out pvt2))
creator2 = Dictionary.GetPrivateCreator(pvt2);
}
var tmpTag = new DicomTag(group2, element2, creator2);
var tmpEntry = Dictionary[tmpTag];
if (!tmpTag.IsPrivate && tmpEntry != null && tmpEntry.MaskTag == null)
{
tmpTag = tmpEntry.Tag; // Use dictionary tag
IsExplicitVR = true;
}
else
{
IsExplicitVR = false;
}
source.Rewind();
}
catch (Exception exin)
{
source.Rewind();
//说明有错误，直接抛出异常
throw new DicomIoException("Auto Check Transfer Syntax Exception by zssure,Details:{0}", exin.StackTrace);
}
}
}
