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 1fa27e38051b97ee4ee09225615041f9921dca56..97ac774c8e2ff329c962e1a77ac9cb5409896b51 100644
--- a/core/src/fpdfapi/fpdf_page/fpdf_page_parser_old.cpp
+++ b/core/src/fpdfapi/fpdf_page/fpdf_page_parser_old.cpp
@@ -7,6 +7,7 @@
 #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>
 
@@ -802,7 +803,7 @@ CFX_ByteString CPDF_StreamParser::ReadString() {
         break;
       case 1:
         if (ch >= '0' && ch <= '7') {
-          iEscCode = ch - '0';
+          iEscCode = FXSYS_toDecimalDigit(ch);
           status = 2;
           break;
         }
@@ -827,7 +828,7 @@ CFX_ByteString CPDF_StreamParser::ReadString() {
         break;
       case 2:
         if (ch >= '0' && ch <= '7') {
-          iEscCode = iEscCode * 8 + ch - '0';
+          iEscCode = iEscCode * 8 + FXSYS_toDecimalDigit(ch);
           status = 3;
         } else {
           buf.AppendChar(iEscCode);
@@ -837,7 +838,7 @@ CFX_ByteString CPDF_StreamParser::ReadString() {
         break;
       case 3:
         if (ch >= '0' && ch <= '7') {
-          iEscCode = iEscCode * 8 + ch - '0';
+          iEscCode = iEscCode * 8 + FXSYS_toDecimalDigit(ch);
           buf.AppendChar(iEscCode);
           status = 0;
         } else {
@@ -870,50 +871,33 @@ CFX_ByteString CPDF_StreamParser::ReadHexString() {
   if (!PositionIsInBounds())
     return CFX_ByteString();
 
-  int ch = m_pBuf[m_Pos++];
   CFX_ByteTextBuf buf;
-  FX_BOOL bFirst = TRUE;
+  bool bFirst = true;
   int code = 0;
-  while (1) {
-    if (ch == '>') {
-      break;
-    }
-    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())
+  while (PositionIsInBounds()) {
+    int ch = m_pBuf[m_Pos++];
+
+    if (ch == '>')
       break;
 
-    ch = m_pBuf[m_Pos++];
+    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 (!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();
 }