Optimize roll operator in CPDF_PSEngine some more.

core/fpdfapi/page/fpdf_page_func.cpp

 // 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 "core/fpdfapi/page/pageint.h"
 
 #include <limits.h>
 
 #include <algorithm>
 #include <memory>
 #include <utility>
 #include <vector>
 
 #include "core/fpdfapi/page/cpdf_psengine.h"
 #include "core/fpdfapi/parser/cpdf_array.h"
 #include "core/fpdfapi/parser/cpdf_dictionary.h"
 #include "core/fpdfapi/parser/cpdf_simple_parser.h"
 #include "core/fpdfapi/parser/cpdf_stream.h"
 #include "core/fpdfapi/parser/cpdf_stream_acc.h"
 #include "core/fxcrt/fx_safe_types.h"
 
+namespace {
+
+const struct PDF_PSOpName {

[Tom Sepez, 2016/10/13 16:21:30]

nit: as long as we're moving this, can we split this into two parts

struct PDF_PSOpName {...};
const PDF_PSOpName g_PSOpNames[] = {{...}};

or whatever ...

[Lei Zhang, 2016/10/13 22:48:19]

Done.

+  const FX_CHAR* name;
+  PDF_PSOP op;
+} PDF_PSOpNames[] = {{"add", PSOP_ADD},         {"sub", PSOP_SUB},
+                     {"mul", PSOP_MUL},         {"div", PSOP_DIV},
+                     {"idiv", PSOP_IDIV},       {"mod", PSOP_MOD},
+                     {"neg", PSOP_NEG},         {"abs", PSOP_ABS},
+                     {"ceiling", PSOP_CEILING}, {"floor", PSOP_FLOOR},
+                     {"round", PSOP_ROUND},     {"truncate", PSOP_TRUNCATE},
+                     {"sqrt", PSOP_SQRT},       {"sin", PSOP_SIN},
+                     {"cos", PSOP_COS},         {"atan", PSOP_ATAN},
+                     {"exp", PSOP_EXP},         {"ln", PSOP_LN},
+                     {"log", PSOP_LOG},         {"cvi", PSOP_CVI},
+                     {"cvr", PSOP_CVR},         {"eq", PSOP_EQ},
+                     {"ne", PSOP_NE},           {"gt", PSOP_GT},
+                     {"ge", PSOP_GE},           {"lt", PSOP_LT},
+                     {"le", PSOP_LE},           {"and", PSOP_AND},
+                     {"or", PSOP_OR},           {"xor", PSOP_XOR},
+                     {"not", PSOP_NOT},         {"bitshift", PSOP_BITSHIFT},
+                     {"true", PSOP_TRUE},       {"false", PSOP_FALSE},
+                     {"if", PSOP_IF},           {"ifelse", PSOP_IFELSE},
+                     {"pop", PSOP_POP},         {"exch", PSOP_EXCH},
+                     {"dup", PSOP_DUP},         {"copy", PSOP_COPY},
+                     {"index", PSOP_INDEX},     {"roll", PSOP_ROLL}};
+
+// See PDF Reference 1.7, page 170, table 3.36.
+bool IsValidBitsPerSample(uint32_t x) {
+  switch (x) {
+    case 1:
+    case 2:
+    case 4:
+    case 8:
+    case 12:
+    case 16:
+    case 24:
+    case 32:
+      return true;
+    default:
+      return false;
+  }
+}
+
+// See PDF Reference 1.7, page 170.
+FX_FLOAT PDF_Interpolate(FX_FLOAT x,
+                         FX_FLOAT xmin,
+                         FX_FLOAT xmax,
+                         FX_FLOAT ymin,
+                         FX_FLOAT ymax) {
+  FX_FLOAT divisor = xmax - xmin;
+  return ymin + (divisor ? (x - xmin) * (ymax - ymin) / divisor : 0);
+}
+
+class CPDF_PSFunc : public CPDF_Function {
+ public:
+  CPDF_PSFunc() : CPDF_Function(Type::kType4PostScript) {}
+  ~CPDF_PSFunc() override {}
+
+  // CPDF_Function
+  FX_BOOL v_Init(CPDF_Object* pObj) override;
+  FX_BOOL v_Call(FX_FLOAT* inputs, FX_FLOAT* results) const override;
+
+ private:
+  CPDF_PSEngine m_PS;
+};
+
+FX_BOOL CPDF_PSFunc::v_Init(CPDF_Object* pObj) {
+  CPDF_StreamAcc acc;
+  acc.LoadAllData(pObj->AsStream(), FALSE);
+  return m_PS.Parse(reinterpret_cast<const FX_CHAR*>(acc.GetData()),
+                    acc.GetSize());
+}
+
+FX_BOOL CPDF_PSFunc::v_Call(FX_FLOAT* inputs, FX_FLOAT* results) const {
+  CPDF_PSEngine& PS = const_cast<CPDF_PSEngine&>(m_PS);
+  PS.Reset();
+  for (uint32_t i = 0; i < m_nInputs; i++)
+    PS.Push(inputs[i]);
+  PS.Execute();
+  if (PS.GetStackSize() < m_nOutputs)
+    return FALSE;
+  for (uint32_t i = 0; i < m_nOutputs; i++)
+    results[m_nOutputs - i - 1] = PS.Pop();
+  return TRUE;
+}
+
+}  // namespace
+
 class CPDF_PSOP {
  public:
   explicit CPDF_PSOP(PDF_PSOP op) : m_op(op), m_value(0) {
     ASSERT(m_op != PSOP_CONST);
     ASSERT(m_op != PSOP_PROC);
   }
   explicit CPDF_PSOP(FX_FLOAT value) : m_op(PSOP_CONST), m_value(value) {}
   explicit CPDF_PSOP(std::unique_ptr<CPDF_PSProc> proc)
       : m_op(PSOP_PROC), m_value(0), m_proc(std::move(proc)) {}
 
@@ skipping 66 matching lines @@
     return;
   }
   m_Stack[m_StackCount++] = v;
 }
 FX_FLOAT CPDF_PSEngine::Pop() {
   if (m_StackCount == 0) {
     return 0;
   }
   return m_Stack[--m_StackCount];
 }
-const struct PDF_PSOpName {
-  const FX_CHAR* name;
-  PDF_PSOP op;
-} PDF_PSOpNames[] = {{"add", PSOP_ADD},         {"sub", PSOP_SUB},
-                     {"mul", PSOP_MUL},         {"div", PSOP_DIV},
-                     {"idiv", PSOP_IDIV},       {"mod", PSOP_MOD},
-                     {"neg", PSOP_NEG},         {"abs", PSOP_ABS},
-                     {"ceiling", PSOP_CEILING}, {"floor", PSOP_FLOOR},
-                     {"round", PSOP_ROUND},     {"truncate", PSOP_TRUNCATE},
-                     {"sqrt", PSOP_SQRT},       {"sin", PSOP_SIN},
-                     {"cos", PSOP_COS},         {"atan", PSOP_ATAN},
-                     {"exp", PSOP_EXP},         {"ln", PSOP_LN},
-                     {"log", PSOP_LOG},         {"cvi", PSOP_CVI},
-                     {"cvr", PSOP_CVR},         {"eq", PSOP_EQ},
-                     {"ne", PSOP_NE},           {"gt", PSOP_GT},
-                     {"ge", PSOP_GE},           {"lt", PSOP_LT},
-                     {"le", PSOP_LE},           {"and", PSOP_AND},
-                     {"or", PSOP_OR},           {"xor", PSOP_XOR},
-                     {"not", PSOP_NOT},         {"bitshift", PSOP_BITSHIFT},
-                     {"true", PSOP_TRUE},       {"false", PSOP_FALSE},
-                     {"if", PSOP_IF},           {"ifelse", PSOP_IFELSE},
-                     {"pop", PSOP_POP},         {"exch", PSOP_EXCH},
-                     {"dup", PSOP_DUP},         {"copy", PSOP_COPY},
-                     {"index", PSOP_INDEX},     {"roll", PSOP_ROLL}};
-
 FX_BOOL CPDF_PSEngine::Parse(const FX_CHAR* str, int size) {
   CPDF_SimpleParser parser((uint8_t*)str, size);
   CFX_ByteStringC word = parser.GetWord();
   if (word != "{") {
     return FALSE;
   }
   return m_MainProc.Parse(&parser, 0);
 }
 
 FX_BOOL CPDF_PSProc::Parse(CPDF_SimpleParser* parser, int depth) {
@@ skipping 244 matching lines @@
     }
     case PSOP_ROLL: {
       int j = static_cast<int>(Pop());
       int n = static_cast<int>(Pop());
       if (j == 0 || n == 0 || m_StackCount == 0)
         break;
       if (n < 0 || n > static_cast<int>(m_StackCount))
         break;
 
       j %= n;
-      if (j < 0) {
-        for (int i = 0; i < -j; i++) {
-          FX_FLOAT first = m_Stack[m_StackCount - n];
-          for (int ii = 0; ii < n - 1; ii++)
-            m_Stack[m_StackCount - n + ii] = m_Stack[m_StackCount - n + ii + 1];
-          m_Stack[m_StackCount - 1] = first;
-        }
-      } else {
-        for (int i = 0; i < j; i++) {
-          FX_FLOAT last = m_Stack[m_StackCount - 1];
-          int ii;
-          for (ii = 0; ii < n - 1; ii++)
-            m_Stack[m_StackCount - ii - 1] = m_Stack[m_StackCount - ii - 2];
-          m_Stack[m_StackCount - ii - 1] = last;
-        }
-      }
+      if (j > 0)
+        j -= n;
+      auto begin_it = std::begin(m_Stack) + m_StackCount - n;
+      auto end_it = begin_it + n;

[Tom Sepez, 2016/10/13 16:21:30]

Maybe it's easier to compute end_it first as
   std::begin() + m_StackCount
then begin_it = end_it - n;

[Lei Zhang, 2016/10/13 22:48:19]

I was trying to keep the arguments to std::rotate() in order. I just wrote it
out for what it is.

+      auto middle_it = begin_it - j;

[Tom Sepez, 2016/10/13 16:21:30]

I'm confused.  Middle comes before begin?

[Lei Zhang, 2016/10/13 22:48:19]

|j| is always negative here. I had it as an addition, but then I had to write:

j = (j > 0) ? n - j : -j;

+      std::rotate(begin_it, middle_it, end_it);
       break;
     }
     default:
       break;
   }
   return TRUE;
 }
 
-// See PDF Reference 1.7, page 170, table 3.36.
-bool IsValidBitsPerSample(uint32_t x) {
-  switch (x) {
-    case 1:
-    case 2:
-    case 4:
-    case 8:
-    case 12:
-    case 16:
-    case 24:
-    case 32:
-      return true;
-    default:
-      return false;
-  }
-}
-
-// See PDF Reference 1.7, page 170.
-FX_FLOAT PDF_Interpolate(FX_FLOAT x,
-                         FX_FLOAT xmin,
-                         FX_FLOAT xmax,
-                         FX_FLOAT ymin,
-                         FX_FLOAT ymax) {
-  FX_FLOAT divisor = xmax - xmin;
-  return ymin + (divisor ? (x - xmin) * (ymax - ymin) / divisor : 0);
-}
-
-class CPDF_PSFunc : public CPDF_Function {
- public:
-  CPDF_PSFunc() : CPDF_Function(Type::kType4PostScript) {}
-  ~CPDF_PSFunc() override {}
-
-  // CPDF_Function
-  FX_BOOL v_Init(CPDF_Object* pObj) override;
-  FX_BOOL v_Call(FX_FLOAT* inputs, FX_FLOAT* results) const override;
-
- private:
-  CPDF_PSEngine m_PS;
-};
-
-FX_BOOL CPDF_PSFunc::v_Init(CPDF_Object* pObj) {
-  CPDF_StreamAcc acc;
-  acc.LoadAllData(pObj->AsStream(), FALSE);
-  return m_PS.Parse(reinterpret_cast<const FX_CHAR*>(acc.GetData()),
-                    acc.GetSize());
-}
-
-FX_BOOL CPDF_PSFunc::v_Call(FX_FLOAT* inputs, FX_FLOAT* results) const {
-  CPDF_PSEngine& PS = const_cast<CPDF_PSEngine&>(m_PS);
-  PS.Reset();
-  for (uint32_t i = 0; i < m_nInputs; i++)
-    PS.Push(inputs[i]);
-  PS.Execute();
-  if (PS.GetStackSize() < m_nOutputs)
-    return FALSE;
-  for (uint32_t i = 0; i < m_nOutputs; i++)
-    results[m_nOutputs - i - 1] = PS.Pop();
-  return TRUE;
-}
-
 CPDF_SampledFunc::CPDF_SampledFunc() : CPDF_Function(Type::kType0Sampled) {}
 
 CPDF_SampledFunc::~CPDF_SampledFunc() {}
 
 FX_BOOL CPDF_SampledFunc::v_Init(CPDF_Object* pObj) {
   CPDF_Stream* pStream = pObj->AsStream();
   if (!pStream)
     return false;
 
   CPDF_Dictionary* pDict = pStream->GetDict();
@@ skipping 359 matching lines @@
   return m_Type == Type::kType2ExpotentialInterpolation
              ? static_cast<const CPDF_ExpIntFunc*>(this)
              : nullptr;
 }
 
 const CPDF_StitchFunc* CPDF_Function::ToStitchFunc() const {
   return m_Type == Type::kType3Stitching
              ? static_cast<const CPDF_StitchFunc*>(this)
              : nullptr;
 }