void readSegment(Jbig2Segment s)
{
int ptr = _ra.FilePointer;
if (s.DataLength == 0xffffffffL)
{
// TODO figure this bit out, 7.2.7
return;
}
byte[] data = new byte[(int)s.DataLength];
_ra.Read(data);
s.Data = data;
if (s.Type == PAGE_INFORMATION)
{
int last = _ra.FilePointer;
_ra.Seek(ptr);
int pageBitmapWidth = _ra.ReadInt();
int pageBitmapHeight = _ra.ReadInt();
_ra.Seek(last);
Jbig2Page p = (Jbig2Page)_pages[s.Page];
if (p == null)
{
throw new InvalidOperationException("referring to widht/height of page we havent seen yet? " + s.Page);
}
p.PageBitmapWidth = pageBitmapWidth;
p.PageBitmapHeight = pageBitmapHeight;
}
}
Jbig2Segment readHeader()
{
int ptr = _ra.FilePointer;
// 7.2.1
int segmentNumber = _ra.ReadInt();
Jbig2Segment s = new Jbig2Segment(segmentNumber);
// 7.2.3
int segmentHeaderFlags = _ra.Read();
bool deferredNonRetain = ((segmentHeaderFlags & 0x80) == 0x80);
s.DeferredNonRetain = deferredNonRetain;
bool pageAssociationSize = ((segmentHeaderFlags & 0x40) == 0x40);
int segmentType = (segmentHeaderFlags & 0x3f);
s.Type = segmentType;
//7.2.4
int referredToByte0 = _ra.Read();
int countOfReferredToSegments = (referredToByte0 & 0xE0) >> 5;
int[] referredToSegmentNumbers;
bool[] segmentRetentionFlags = null;
if (countOfReferredToSegments == 7)
{
// at least five bytes
_ra.Seek(_ra.FilePointer - 1);
countOfReferredToSegments = (_ra.ReadInt() & 0x1fffffff);
segmentRetentionFlags = new bool[countOfReferredToSegments + 1];
int i = 0;
int referredToCurrentByte = 0;
do
{
int j = i % 8;
if (j == 0)
{
referredToCurrentByte = _ra.Read();
}
segmentRetentionFlags[i] = ((((0x1 << j) & referredToCurrentByte) >> j) == 0x1);
i++;
} while (i <= countOfReferredToSegments);
}
else if (countOfReferredToSegments <= 4)
{
// only one byte
segmentRetentionFlags = new bool[countOfReferredToSegments + 1];
referredToByte0 &= 0x1f;
for (int i = 0; i <= countOfReferredToSegments; i++)
{
segmentRetentionFlags[i] = ((((0x1 << i) & referredToByte0) >> i) == 0x1);
}
}
else if (countOfReferredToSegments == 5 || countOfReferredToSegments == 6)
{
throw new InvalidOperationException("count of referred-to segments had bad value in header for segment " + segmentNumber + " starting at " + ptr);
}
s.SegmentRetentionFlags = segmentRetentionFlags;
s.CountOfReferredToSegments = countOfReferredToSegments;
// 7.2.5
referredToSegmentNumbers = new int[countOfReferredToSegments + 1];
for (int i = 1; i <= countOfReferredToSegments; i++)
{
if (segmentNumber <= 256)
{
referredToSegmentNumbers[i] = _ra.Read();
}
else if (segmentNumber <= 65536)
{
referredToSegmentNumbers[i] = _ra.ReadUnsignedShort();
}
else
{
referredToSegmentNumbers[i] = (int)_ra.ReadUnsignedInt(); // TODO wtf ack
}
}
s.ReferredToSegmentNumbers = referredToSegmentNumbers;
// 7.2.6
int segmentPageAssociation;
int pageAssociationOffset = _ra.FilePointer - ptr;
if (pageAssociationSize)
{
segmentPageAssociation = _ra.ReadInt();
}
else
{
segmentPageAssociation = _ra.Read();
}
if (segmentPageAssociation < 0)
{
throw new InvalidOperationException("page " + segmentPageAssociation + " invalid for segment " + segmentNumber + " starting at " + ptr);
}
s.Page = segmentPageAssociation;
// so we can change the page association at embedding time.
s.PageAssociationSize = pageAssociationSize;
s.PageAssociationOffset = pageAssociationOffset;
if (segmentPageAssociation > 0 && !_pages.ContainsKey(segmentPageAssociation))
{
_pages[segmentPageAssociation] = new Jbig2Page(segmentPageAssociation, this);
}
if (segmentPageAssociation > 0)
{
((Jbig2Page)_pages[segmentPageAssociation]).AddSegment(s);
}
else
{
_globals[s] = null;
}
// 7.2.7
long segmentDataLength = _ra.ReadUnsignedInt();
// TODO the 0xffffffff value that might be here, and how to understand those afflicted segments
s.DataLength = segmentDataLength;
int endPtr = _ra.FilePointer;
_ra.Seek(ptr);
byte[] headerData = new byte[endPtr - ptr];
_ra.Read(headerData);
s.HeaderData = headerData;
return(s);
}
