fenix/PDF4QT
1
0
Fork 0
mirror of https://github.com/JakubMelka/PDF4QT.git synced 2025-06-05 21:59:17 +02:00
Code Issues Packages Projects Releases Wiki Activity

JBIG2 - arithmetic decoder bugfixing

Browse Source
This commit is contained in:
Jakub Melka
2019-10-29 15:34:09 +01:00
parent 34371706aa
commit 489033c4ce
4 changed files with 89 additions and 14 deletions
Download Patch File Download Diff File Expand all files Collapse all files

17
PdfForQtLib/sources/pdfjbig2decoder.h
View File

@ -43,7 +43,7 @@ enum class PDFJBIG2BitOperation
/// state is stored as 8-bit value, where only 7 bits are used. 6 bits are used
/// to store Qe value index (current row in the table, number 0-46), and lowest 1 bit
/// is used to store current MPS value (most probable symbol - 0/1).
class PDFJBIG2ArithmeticDecoderState
class PDFFORQTLIBSHARED_EXPORT PDFJBIG2ArithmeticDecoderState
{
public:
explicit inline PDFJBIG2ArithmeticDecoderState() = default;
@ -72,6 +72,10 @@ public:
return m_state[context] >> 1;
}
/// Returns Qe value for row index, according to document ISO/IEC 14492:2001,
/// annex E, table E.1 (Qe values and probability estimation process).
inline uint32_t getQe(size_t context) const;
/// Returns current bit value of MPS (most probable symbol)
inline uint8_t getMPS(size_t context) const
{
@ -96,13 +100,14 @@ private:
/// of decoder described in document ISO/IEC 14492:2001, T.88, annex G (arithmetic decoding
/// procedure). It uses 32-bit fixed point arithmetic instead of 16-bit fixed point
/// arithmetic described in the specification (it is much faster).
class PDFJBIG2ArithmeticDecoder
class PDFFORQTLIBSHARED_EXPORT PDFJBIG2ArithmeticDecoder
{
public:
explicit inline PDFJBIG2ArithmeticDecoder(PDFBitReader* reader) :
m_c(0),
m_a(0),
m_ct(0),
m_lastByte(0),
m_reader(reader)
{
@ -110,6 +115,11 @@ public:
void initialize() { perform_INITDEC(); }
uint32_t readBit(size_t context, PDFJBIG2ArithmeticDecoderState* state) { return perform_DECODE(context, state); }
uint32_t readByte(size_t context, PDFJBIG2ArithmeticDecoderState* state);
uint32_t getRegisterC() const { return m_c; }
uint32_t getRegisterA() const { return m_a; }
uint32_t getRegisterCT() const { return m_ct; }
private:
/// Performs INITDEC operation as described in the specification
@ -136,6 +146,9 @@ private:
/// Number of current unprocessed bits.
uint32_t m_ct;
/// Last processed byte
uint8_t m_lastByte;
/// Data source to read from
PDFBitReader* m_reader;
};