Cleanup CJBig2_ArithDecoder.
R=tsepez@chromium.org
Review URL: https://codereview.chromium.org/1368153003 .
diff --git a/core/src/fxcodec/jbig2/JBig2_ArithDecoder.cpp b/core/src/fxcodec/jbig2/JBig2_ArithDecoder.cpp
index 34c79f9..a1aa5bf 100644
--- a/core/src/fxcodec/jbig2/JBig2_ArithDecoder.cpp
+++ b/core/src/fxcodec/jbig2/JBig2_ArithDecoder.cpp
@@ -8,7 +8,6 @@
#include "../../../include/fxcrt/fx_basic.h"
#include "JBig2_BitStream.h"
-#include "JBig2_Define.h"
namespace {
@@ -69,98 +68,85 @@
{0x0001, 45, 43, 0},
{0x5601, 46, 46, 0}};
+const unsigned int kDefaultAValue = 0x8000;
+
+int DecodeNMPS(JBig2ArithCtx* pCX, const JBig2ArithQe& qe) {
+ pCX->I = qe.NMPS;
+ return pCX->MPS;
+}
+
+int DecodeNLPS(JBig2ArithCtx* pCX, const JBig2ArithQe& qe) {
+ // TODO(thestig): |D|, |MPS| and friends probably should be booleans.
+ int D = 1 - pCX->MPS;
+ if (qe.nSwitch == 1)
+ pCX->MPS = 1 - pCX->MPS;
+ pCX->I = qe.NLPS;
+ return D;
+}
+
} // namespace
-CJBig2_ArithDecoder::CJBig2_ArithDecoder(CJBig2_BitStream* pStream) {
- m_pStream = pStream;
- INITDEC();
+CJBig2_ArithDecoder::CJBig2_ArithDecoder(CJBig2_BitStream* pStream)
+ : m_pStream(pStream) {
+ m_B = m_pStream->getCurByte_arith();
+ m_C = (m_B ^ 0xff) << 16;
+ BYTEIN();
+ m_C = m_C << 7;
+ m_CT = m_CT - 7;
+ m_A = kDefaultAValue;
}
CJBig2_ArithDecoder::~CJBig2_ArithDecoder() {
}
int CJBig2_ArithDecoder::DECODE(JBig2ArithCtx* pCX) {
- if (!pCX || pCX->I >= FX_ArraySize(kQeTable)) {
+ if (!pCX || pCX->I >= FX_ArraySize(kQeTable))
return 0;
+
+ const JBig2ArithQe& qe = kQeTable[pCX->I];
+ m_A -= qe.Qe;
+ if ((m_C >> 16) < m_A) {
+ if (m_A & kDefaultAValue)
+ return pCX->MPS;
+
+ const int D = m_A < qe.Qe ? DecodeNLPS(pCX, qe) : DecodeNMPS(pCX, qe);
+ ReadValueA();
+ return D;
}
- int D;
- const JBig2ArithQe* qe = &kQeTable[pCX->I];
- A = A - qe->Qe;
- if ((C >> 16) < A) {
- if (A & 0x8000) {
- D = pCX->MPS;
- } else {
- if (A < qe->Qe) {
- D = 1 - pCX->MPS;
- if (qe->nSwitch == 1) {
- pCX->MPS = 1 - pCX->MPS;
- }
- pCX->I = qe->NLPS;
- } else {
- D = pCX->MPS;
- pCX->I = qe->NMPS;
- }
- do {
- if (CT == 0) {
- BYTEIN();
- }
- A <<= 1;
- C <<= 1;
- CT--;
- } while ((A & 0x8000) == 0);
- }
- } else {
- C -= A << 16;
- if (A < qe->Qe) {
- A = qe->Qe;
- D = pCX->MPS;
- pCX->I = qe->NMPS;
- } else {
- A = qe->Qe;
- D = 1 - pCX->MPS;
- if (qe->nSwitch == 1) {
- pCX->MPS = 1 - pCX->MPS;
- }
- pCX->I = qe->NLPS;
- }
- do {
- if (CT == 0) {
- BYTEIN();
- }
- A <<= 1;
- C <<= 1;
- CT--;
- } while ((A & 0x8000) == 0);
- }
+ m_C -= m_A << 16;
+ const int D = m_A < qe.Qe ? DecodeNMPS(pCX, qe) : DecodeNLPS(pCX, qe);
+ m_A = qe.Qe;
+ ReadValueA();
return D;
}
-void CJBig2_ArithDecoder::INITDEC() {
- B = m_pStream->getCurByte_arith();
- C = (B ^ 0xff) << 16;
- BYTEIN();
- C = C << 7;
- CT = CT - 7;
- A = 0x8000;
-}
-
void CJBig2_ArithDecoder::BYTEIN() {
unsigned char B1;
- if (B == 0xff) {
+ if (m_B == 0xff) {
B1 = m_pStream->getNextByte_arith();
if (B1 > 0x8f) {
- CT = 8;
+ m_CT = 8;
} else {
m_pStream->incByteIdx();
- B = B1;
- C = C + 0xfe00 - (B << 9);
- CT = 7;
+ m_B = B1;
+ m_C = m_C + 0xfe00 - (m_B << 9);
+ m_CT = 7;
}
} else {
m_pStream->incByteIdx();
- B = m_pStream->getCurByte_arith();
- C = C + 0xff00 - (B << 8);
- CT = 8;
+ m_B = m_pStream->getCurByte_arith();
+ m_C = m_C + 0xff00 - (m_B << 8);
+ m_CT = 8;
}
}
+
+void CJBig2_ArithDecoder::ReadValueA() {
+ do {
+ if (m_CT == 0)
+ BYTEIN();
+ m_A <<= 1;
+ m_C <<= 1;
+ --m_CT;
+ } while ((m_A & kDefaultAValue) == 0);
+}
diff --git a/core/src/fxcodec/jbig2/JBig2_ArithDecoder.h b/core/src/fxcodec/jbig2/JBig2_ArithDecoder.h
index 02c81b3..a1e8910 100644
--- a/core/src/fxcodec/jbig2/JBig2_ArithDecoder.h
+++ b/core/src/fxcodec/jbig2/JBig2_ArithDecoder.h
@@ -23,14 +23,14 @@
int DECODE(JBig2ArithCtx* pCX);
private:
- void INITDEC();
void BYTEIN();
+ void ReadValueA();
- unsigned char B;
- unsigned int C;
- unsigned int A;
- unsigned int CT;
- CJBig2_BitStream* m_pStream;
+ unsigned char m_B;
+ unsigned int m_C;
+ unsigned int m_A;
+ unsigned int m_CT;
+ CJBig2_BitStream* const m_pStream;
};
#endif // CORE_SRC_FXCODEC_JBIG2_JBIG2_ARITHDECODER_H_
