Revert "Revert "Revert "Cleanup some numeric code."""

core/src/fpdfapi/fpdf_page/fpdf_page_parser_old.cpp

Index: core/src/fpdfapi/fpdf_page/fpdf_page_parser_old.cpp
diff --git a/core/src/fpdfapi/fpdf_page/fpdf_page_parser_old.cpp b/core/src/fpdfapi/fpdf_page/fpdf_page_parser_old.cpp
index 5e312e3eecb1c00d2440491faf50b7d78709286b..187d6152e96ceccc76c7f7ee4be604d6aa1d40da 100644
--- a/core/src/fpdfapi/fpdf_page/fpdf_page_parser_old.cpp
+++ b/core/src/fpdfapi/fpdf_page/fpdf_page_parser_old.cpp
@@ -7,7 +7,6 @@
 #include "../../../include/fpdfapi/fpdf_page.h"
 #include "../../../include/fpdfapi/fpdf_module.h"
 #include "../../../include/fxcodec/fx_codec.h"
-#include "../../../include/fxcrt/fx_ext.h"
 #include "pageint.h"
 #include <limits.h>
 
@@ -789,7 +788,7 @@ CFX_ByteString CPDF_StreamParser::ReadString() {
         break;
       case 1:
         if (ch >= '0' && ch <= '7') {
-          iEscCode = FXSYS_toDecimalDigit(ch);
+          iEscCode = ch - '0';
           status = 2;
           break;
         }
@@ -814,7 +813,7 @@ CFX_ByteString CPDF_StreamParser::ReadString() {
         break;
       case 2:
         if (ch >= '0' && ch <= '7') {
-          iEscCode = iEscCode * 8 + FXSYS_toDecimalDigit(ch);
+          iEscCode = iEscCode * 8 + ch - '0';
           status = 3;
         } else {
           buf.AppendChar(iEscCode);
@@ -824,7 +823,7 @@ CFX_ByteString CPDF_StreamParser::ReadString() {
         break;
       case 3:
         if (ch >= '0' && ch <= '7') {
-          iEscCode = iEscCode * 8 + FXSYS_toDecimalDigit(ch);
+          iEscCode = iEscCode * 8 + ch - '0';
           buf.AppendChar(iEscCode);
           status = 0;
         } else {
@@ -857,33 +856,50 @@ CFX_ByteString CPDF_StreamParser::ReadHexString() {
   if (!PositionIsInBounds())
     return CFX_ByteString();
 
+  int ch = m_pBuf[m_Pos++];
   CFX_ByteTextBuf buf;
-  bool bFirst = true;
+  FX_BOOL bFirst = TRUE;
   int code = 0;
-  while (PositionIsInBounds()) {
-    int ch = m_pBuf[m_Pos++];
-
-    if (ch == '>')
+  while (1) {
+    if (ch == '>') {
       break;
-
-    if (!std::isxdigit(ch))
-      continue;
-
-    int val = FXSYS_toHexDigit(ch);
-    if (bFirst) {
-      code = val * 16;
-    } else {
-      code += val;
-      buf.AppendByte((uint8_t)code);
     }
-    bFirst = !bFirst;
+    if (ch >= '0' && ch <= '9') {
+      if (bFirst) {
+        code = (ch - '0') * 16;
+      } else {
+        code += ch - '0';
+        buf.AppendChar((char)code);
+      }
+      bFirst = !bFirst;
+    } else if (ch >= 'A' && ch <= 'F') {
+      if (bFirst) {
+        code = (ch - 'A' + 10) * 16;
+      } else {
+        code += ch - 'A' + 10;
+        buf.AppendChar((char)code);
+      }
+      bFirst = !bFirst;
+    } else if (ch >= 'a' && ch <= 'f') {
+      if (bFirst) {
+        code = (ch - 'a' + 10) * 16;
+      } else {
+        code += ch - 'a' + 10;
+        buf.AppendChar((char)code);
+      }
+      bFirst = !bFirst;
+    }
+    if (!PositionIsInBounds())
+      break;
+
+    ch = m_pBuf[m_Pos++];
   }
-  if (!bFirst)
+  if (!bFirst) {
     buf.AppendChar((char)code);
-
-  if (buf.GetLength() > MAX_STRING_LENGTH)
+  }
+  if (buf.GetLength() > MAX_STRING_LENGTH) {
     return CFX_ByteString(buf.GetBuffer(), MAX_STRING_LENGTH);
-
+  }
   return buf.GetByteString();
 }