1 files changed, 166 insertions, 0 deletions
diff --git a/core/src/fxcodec/jbig2/JBig2_ArithDecoder.cpp b/core/src/fxcodec/jbig2/JBig2_ArithDecoder.cpp
new file mode 100644
index 0000000000..34c79f9fa3
--- /dev/null
+++ b/core/src/fxcodec/jbig2/JBig2_ArithDecoder.cpp
@@ -0,0 +1,166 @@
+// Copyright 2014 PDFium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
+
+#include "JBig2_ArithDecoder.h"
+
+#include "../../../include/fxcrt/fx_basic.h"
+#include "JBig2_BitStream.h"
+#include "JBig2_Define.h"
+
+namespace {
+
+struct JBig2ArithQe {
+  unsigned int Qe;
+  unsigned int NMPS;
+  unsigned int NLPS;
+  unsigned int nSwitch;
+};
+
+const JBig2ArithQe kQeTable[] = {
+    // Stupid hack to keep clang-format from reformatting this badly.
+    {0x5601, 1, 1, 1},
+    {0x3401, 2, 6, 0},
+    {0x1801, 3, 9, 0},
+    {0x0AC1, 4, 12, 0},
+    {0x0521, 5, 29, 0},
+    {0x0221, 38, 33, 0},
+    {0x5601, 7, 6, 1},
+    {0x5401, 8, 14, 0},
+    {0x4801, 9, 14, 0},
+    {0x3801, 10, 14, 0},
+    {0x3001, 11, 17, 0},
+    {0x2401, 12, 18, 0},
+    {0x1C01, 13, 20, 0},
+    {0x1601, 29, 21, 0},
+    {0x5601, 15, 14, 1},
+    {0x5401, 16, 14, 0},
+    {0x5101, 17, 15, 0},
+    {0x4801, 18, 16, 0},
+    {0x3801, 19, 17, 0},
+    {0x3401, 20, 18, 0},
+    {0x3001, 21, 19, 0},
+    {0x2801, 22, 19, 0},
+    {0x2401, 23, 20, 0},
+    {0x2201, 24, 21, 0},
+    {0x1C01, 25, 22, 0},
+    {0x1801, 26, 23, 0},
+    {0x1601, 27, 24, 0},
+    {0x1401, 28, 25, 0},
+    {0x1201, 29, 26, 0},
+    {0x1101, 30, 27, 0},
+    {0x0AC1, 31, 28, 0},
+    {0x09C1, 32, 29, 0},
+    {0x08A1, 33, 30, 0},
+    {0x0521, 34, 31, 0},
+    {0x0441, 35, 32, 0},
+    {0x02A1, 36, 33, 0},
+    {0x0221, 37, 34, 0},
+    {0x0141, 38, 35, 0},
+    {0x0111, 39, 36, 0},
+    {0x0085, 40, 37, 0},
+    {0x0049, 41, 38, 0},
+    {0x0025, 42, 39, 0},
+    {0x0015, 43, 40, 0},
+    {0x0009, 44, 41, 0},
+    {0x0005, 45, 42, 0},
+    {0x0001, 45, 43, 0},
+    {0x5601, 46, 46, 0}};
+
+}  // namespace
+
+CJBig2_ArithDecoder::CJBig2_ArithDecoder(CJBig2_BitStream* pStream) {
+  m_pStream = pStream;
+  INITDEC();
+}
+
+CJBig2_ArithDecoder::~CJBig2_ArithDecoder() {
+}
+
+int CJBig2_ArithDecoder::DECODE(JBig2ArithCtx* pCX) {
+  if (!pCX || pCX->I >= FX_ArraySize(kQeTable)) {
+    return 0;
+  }
+
+  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);
+  }
+  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) {
+    B1 = m_pStream->getNextByte_arith();
+    if (B1 > 0x8f) {
+      CT = 8;
+    } else {
+      m_pStream->incByteIdx();
+      B = B1;
+      C = C + 0xfe00 - (B << 9);
+      CT = 7;
+    }
+  } else {
+    m_pStream->incByteIdx();
+    B = m_pStream->getCurByte_arith();
+    C = C + 0xff00 - (B << 8);
+    CT = 8;
+  }
+}