Add helper methods in CJBig2_GRRDProc.

Refactor identical code used in decode_Template0_unopt() into their own
methods.

Change-Id: I37348a280ecc66d91fdcd3c9aabe49d2a8065417
Reviewed-on: https://pdfium-review.googlesource.com/11950
Reviewed-by: Ryan Harrison <rharrison@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>

4 files changed, 70 insertions, 86 deletions

diff --git a/core/fxcodec/jbig2/JBig2_GrrdProc.cpp b/core/fxcodec/jbig2/JBig2_GrrdProc.cpp
index 049e50a1a9..71bd8e53e4 100644
--- a/core/fxcodec/jbig2/JBig2_GrrdProc.cpp
+++ b/core/fxcodec/jbig2/JBig2_GrrdProc.cpp
@@ -45,71 +45,31 @@ std::unique_ptr<CJBig2_Image> CJBig2_GRRDProc::decode_Template0_unopt(
   for (uint32_t h = 0; h < GRH; h++) {
     if (TPGRON)
       LTP = LTP ^ pArithDecoder->DECODE(&grContext[0x0010]);
+
+    uint32_t lines[5];
+    lines[0] = GRREG->getPixel(1, h - 1);
+    lines[0] |= GRREG->getPixel(0, h - 1) << 1;
+    lines[1] = 0;
+    lines[2] = GRREFERENCE->getPixel(-GRREFERENCEDX + 1, h - GRREFERENCEDY - 1);
+    lines[2] |= GRREFERENCE->getPixel(-GRREFERENCEDX, h - GRREFERENCEDY - 1)
+                << 1;
+    lines[3] = GRREFERENCE->getPixel(-GRREFERENCEDX + 1, h - GRREFERENCEDY);
+    lines[3] |= GRREFERENCE->getPixel(-GRREFERENCEDX, h - GRREFERENCEDY) << 1;
+    lines[3] |= GRREFERENCE->getPixel(-GRREFERENCEDX - 1, h - GRREFERENCEDY)
+                << 2;
+    lines[4] = GRREFERENCE->getPixel(-GRREFERENCEDX + 1, h - GRREFERENCEDY + 1);
+    lines[4] |= GRREFERENCE->getPixel(-GRREFERENCEDX, h - GRREFERENCEDY + 1)
+                << 1;
+    lines[4] |= GRREFERENCE->getPixel(-GRREFERENCEDX - 1, h - GRREFERENCEDY + 1)
+                << 2;
     if (!LTP) {
-      uint32_t line1 = GRREG->getPixel(1, h - 1);
-      line1 |= GRREG->getPixel(0, h - 1) << 1;
-      uint32_t line2 = 0;
-      uint32_t line3 =
-          GRREFERENCE->getPixel(-GRREFERENCEDX + 1, h - GRREFERENCEDY - 1);
-      line3 |= GRREFERENCE->getPixel(-GRREFERENCEDX, h - GRREFERENCEDY - 1)
-               << 1;
-      uint32_t line4 =
-          GRREFERENCE->getPixel(-GRREFERENCEDX + 1, h - GRREFERENCEDY);
-      line4 |= GRREFERENCE->getPixel(-GRREFERENCEDX, h - GRREFERENCEDY) << 1;
-      line4 |= GRREFERENCE->getPixel(-GRREFERENCEDX - 1, h - GRREFERENCEDY)
-               << 2;
-      uint32_t line5 =
-          GRREFERENCE->getPixel(-GRREFERENCEDX + 1, h - GRREFERENCEDY + 1);
-      line5 |= GRREFERENCE->getPixel(-GRREFERENCEDX, h - GRREFERENCEDY + 1)
-               << 1;
-      line5 |= GRREFERENCE->getPixel(-GRREFERENCEDX - 1, h - GRREFERENCEDY + 1)
-               << 2;
       for (uint32_t w = 0; w < GRW; w++) {
-        uint32_t CONTEXT = line5;
-        CONTEXT |= line4 << 3;
-        CONTEXT |= line3 << 6;
-        CONTEXT |= GRREFERENCE->getPixel(w - GRREFERENCEDX + GRAT[2],
-                                         h - GRREFERENCEDY + GRAT[3])
-                   << 8;
-        CONTEXT |= line2 << 9;
-        CONTEXT |= line1 << 10;
-        CONTEXT |= GRREG->getPixel(w + GRAT[0], h + GRAT[1]) << 12;
+        uint32_t CONTEXT =
+            decode_Template0_unopt_CalculateContext(*GRREG, lines, w, h);
         int bVal = pArithDecoder->DECODE(&grContext[CONTEXT]);
-        GRREG->setPixel(w, h, bVal);
-        line1 = ((line1 << 1) | GRREG->getPixel(w + 2, h - 1)) & 0x03;
-        line2 = ((line2 << 1) | bVal) & 0x01;
-        line3 = ((line3 << 1) |
-                 GRREFERENCE->getPixel(w - GRREFERENCEDX + 2,
-                                       h - GRREFERENCEDY - 1)) &
-                0x03;
-        line4 =
-            ((line4 << 1) |
-             GRREFERENCE->getPixel(w - GRREFERENCEDX + 2, h - GRREFERENCEDY)) &
-            0x07;
-        line5 = ((line5 << 1) |
-                 GRREFERENCE->getPixel(w - GRREFERENCEDX + 2,
-                                       h - GRREFERENCEDY + 1)) &
-                0x07;
+        decode_Template0_unopt_SetPixel(GRREG.get(), lines, w, h, bVal);
       }
     } else {
-      uint32_t line1 = GRREG->getPixel(1, h - 1);
-      line1 |= GRREG->getPixel(0, h - 1) << 1;
-      uint32_t line2 = 0;
-      uint32_t line3 =
-          GRREFERENCE->getPixel(-GRREFERENCEDX + 1, h - GRREFERENCEDY - 1);
-      line3 |= GRREFERENCE->getPixel(-GRREFERENCEDX, h - GRREFERENCEDY - 1)
-               << 1;
-      uint32_t line4 =
-          GRREFERENCE->getPixel(-GRREFERENCEDX + 1, h - GRREFERENCEDY);
-      line4 |= GRREFERENCE->getPixel(-GRREFERENCEDX, h - GRREFERENCEDY) << 1;
-      line4 |= GRREFERENCE->getPixel(-GRREFERENCEDX - 1, h - GRREFERENCEDY)
-               << 2;
-      uint32_t line5 =
-          GRREFERENCE->getPixel(-GRREFERENCEDX + 1, h - GRREFERENCEDY + 1);
-      line5 |= GRREFERENCE->getPixel(-GRREFERENCEDX, h - GRREFERENCEDY + 1)
-               << 1;
-      line5 |= GRREFERENCE->getPixel(-GRREFERENCEDX - 1, h - GRREFERENCEDY + 1)
-               << 2;
       for (uint32_t w = 0; w < GRW; w++) {
         int bVal = GRREFERENCE->getPixel(w, h);
         if (!(TPGRON && (bVal == GRREFERENCE->getPixel(w - 1, h - 1)) &&
@@ -120,38 +80,53 @@ std::unique_ptr<CJBig2_Image> CJBig2_GRRDProc::decode_Template0_unopt(
               (bVal == GRREFERENCE->getPixel(w - 1, h + 1)) &&
               (bVal == GRREFERENCE->getPixel(w, h + 1)) &&
               (bVal == GRREFERENCE->getPixel(w + 1, h + 1)))) {
-          uint32_t CONTEXT = line5;
-          CONTEXT |= line4 << 3;
-          CONTEXT |= line3 << 6;
-          CONTEXT |= GRREFERENCE->getPixel(w - GRREFERENCEDX + GRAT[2],
-                                           h - GRREFERENCEDY + GRAT[3])
-                     << 8;
-          CONTEXT |= line2 << 9;
-          CONTEXT |= line1 << 10;
-          CONTEXT |= GRREG->getPixel(w + GRAT[0], h + GRAT[1]) << 12;
+          uint32_t CONTEXT =
+              decode_Template0_unopt_CalculateContext(*GRREG, lines, w, h);
           bVal = pArithDecoder->DECODE(&grContext[CONTEXT]);
         }
-        GRREG->setPixel(w, h, bVal);
-        line1 = ((line1 << 1) | GRREG->getPixel(w + 2, h - 1)) & 0x03;
-        line2 = ((line2 << 1) | bVal) & 0x01;
-        line3 = ((line3 << 1) |
-                 GRREFERENCE->getPixel(w - GRREFERENCEDX + 2,
-                                       h - GRREFERENCEDY - 1)) &
-                0x03;
-        line4 =
-            ((line4 << 1) |
-             GRREFERENCE->getPixel(w - GRREFERENCEDX + 2, h - GRREFERENCEDY)) &
-            0x07;
-        line5 = ((line5 << 1) |
-                 GRREFERENCE->getPixel(w - GRREFERENCEDX + 2,
-                                       h - GRREFERENCEDY + 1)) &
-                0x07;
+        decode_Template0_unopt_SetPixel(GRREG.get(), lines, w, h, bVal);
       }
     }
   }
   return GRREG;
 }
 
+uint32_t CJBig2_GRRDProc::decode_Template0_unopt_CalculateContext(
+    const CJBig2_Image& GRREG,
+    const uint32_t* lines,
+    uint32_t w,
+    uint32_t h) const {
+  uint32_t CONTEXT = lines[4];
+  CONTEXT |= lines[3] << 3;
+  CONTEXT |= lines[2] << 6;
+  CONTEXT |= GRREFERENCE->getPixel(w - GRREFERENCEDX + GRAT[2],
+                                   h - GRREFERENCEDY + GRAT[3])
+             << 8;
+  CONTEXT |= lines[1] << 9;
+  CONTEXT |= lines[0] << 10;
+  CONTEXT |= GRREG.getPixel(w + GRAT[0], h + GRAT[1]) << 12;
+  return CONTEXT;
+}
+
+void CJBig2_GRRDProc::decode_Template0_unopt_SetPixel(CJBig2_Image* GRREG,
+                                                      uint32_t* lines,
+                                                      uint32_t w,
+                                                      uint32_t h,
+                                                      int bVal) {
+  GRREG->setPixel(w, h, bVal);
+  lines[0] = ((lines[0] << 1) | GRREG->getPixel(w + 2, h - 1)) & 0x03;
+  lines[1] = ((lines[1] << 1) | bVal) & 0x01;
+  lines[2] = ((lines[2] << 1) | GRREFERENCE->getPixel(w - GRREFERENCEDX + 2,
+                                                      h - GRREFERENCEDY - 1)) &
+             0x03;
+  lines[3] = ((lines[3] << 1) |
+              GRREFERENCE->getPixel(w - GRREFERENCEDX + 2, h - GRREFERENCEDY)) &
+             0x07;
+  lines[4] = ((lines[4] << 1) | GRREFERENCE->getPixel(w - GRREFERENCEDX + 2,
+                                                      h - GRREFERENCEDY + 1)) &
+             0x07;
+}
+
 std::unique_ptr<CJBig2_Image> CJBig2_GRRDProc::decode_Template0_opt(
     CJBig2_ArithDecoder* pArithDecoder,
     JBig2ArithCtx* grContext) {
diff --git a/core/fxcodec/jbig2/JBig2_GrrdProc.h b/core/fxcodec/jbig2/JBig2_GrrdProc.h
index 43f535335d..a9a14398fe 100644
--- a/core/fxcodec/jbig2/JBig2_GrrdProc.h
+++ b/core/fxcodec/jbig2/JBig2_GrrdProc.h
@@ -33,6 +33,15 @@ class CJBig2_GRRDProc {
   std::unique_ptr<CJBig2_Image> decode_Template0_unopt(
       CJBig2_ArithDecoder* pArithDecoder,
       JBig2ArithCtx* grContext);
+  uint32_t decode_Template0_unopt_CalculateContext(const CJBig2_Image& GRREG,
+                                                   const uint32_t* lines,
+                                                   uint32_t w,
+                                                   uint32_t h) const;
+  void decode_Template0_unopt_SetPixel(CJBig2_Image* GRREG,
+                                       uint32_t* lines,
+                                       uint32_t w,
+                                       uint32_t h,
+                                       int bVal);
 
   std::unique_ptr<CJBig2_Image> decode_Template0_opt(
       CJBig2_ArithDecoder* pArithDecoder,
diff --git a/core/fxcodec/jbig2/JBig2_Image.cpp b/core/fxcodec/jbig2/JBig2_Image.cpp
index f026ce660b..e07eb32fe3 100644
--- a/core/fxcodec/jbig2/JBig2_Image.cpp
+++ b/core/fxcodec/jbig2/JBig2_Image.cpp
@@ -74,7 +74,7 @@ CJBig2_Image::~CJBig2_Image() {
   }
 }
 
-int CJBig2_Image::getPixel(int32_t x, int32_t y) {
+int CJBig2_Image::getPixel(int32_t x, int32_t y) const {
   if (!m_pData)
     return 0;
 
diff --git a/core/fxcodec/jbig2/JBig2_Image.h b/core/fxcodec/jbig2/JBig2_Image.h
index 807468aa0b..1f418fb7e2 100644
--- a/core/fxcodec/jbig2/JBig2_Image.h
+++ b/core/fxcodec/jbig2/JBig2_Image.h
@@ -32,7 +32,7 @@ class CJBig2_Image {
   int32_t height() const { return m_nHeight; }
   int32_t stride() const { return m_nStride; }
 
-  int getPixel(int32_t x, int32_t y);
+  int getPixel(int32_t x, int32_t y) const;
   int32_t setPixel(int32_t x, int32_t y, int bVal);
 
   void copyLine(int32_t hTo, int32_t hFrom);