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

core/src/fpdfapi/fpdf_font/fpdf_font.cpp

Index: core/src/fpdfapi/fpdf_font/fpdf_font.cpp
diff --git a/core/src/fpdfapi/fpdf_font/fpdf_font.cpp b/core/src/fpdfapi/fpdf_font/fpdf_font.cpp
index 2d5e9780ad2bf683d9366a449c7ce27a7f1571c1..0529d3d35b7e1605e548d568f22a356885c05159 100644
--- a/core/src/fpdfapi/fpdf_font/fpdf_font.cpp
+++ b/core/src/fpdfapi/fpdf_font/fpdf_font.cpp
@@ -8,7 +8,6 @@
 #include "../../../include/fpdfapi/fpdf_page.h"
 #include "../../../include/fpdfapi/fpdf_pageobj.h"
 #include "../../../include/fpdfapi/fpdf_resource.h"
-#include "../../../include/fxcrt/fx_ext.h"
 #include "../../../include/fxge/fx_freetype.h"
 #include "../fpdf_page/pageint.h"
 #include "font_int.h"
@@ -514,19 +513,32 @@ FX_DWORD CPDF_ToUnicodeMap::ReverseLookup(FX_WCHAR unicode) {
 FX_DWORD CPDF_ToUnicodeMap::StringToCode(const CFX_ByteStringC& str) {
   const FX_CHAR* buf = str.GetCStr();
   int len = str.GetLength();
-  if (len == 0)
+  if (len == 0) {
     return 0;
-
+  }
   int result = 0;
   if (buf[0] == '<') {
-    for (int i = 1; i < len && std::isxdigit(buf[i]); ++i)
-      result = result * 16 + FXSYS_toHexDigit(buf[i]);
+    for (int i = 1; i < len; i++) {
+      int digit;
+      if (buf[i] >= '0' && buf[i] <= '9') {
+        digit = buf[i] - '0';
+      } else if (buf[i] >= 'a' && buf[i] <= 'f') {
+        digit = buf[i] - 'a' + 10;
+      } else if (buf[i] >= 'A' && buf[i] <= 'F') {
+        digit = buf[i] - 'A' + 10;
+      } else {
+        break;
+      }
+      result = result * 16 + digit;
+    }
     return result;
   }
-
-  for (int i = 0; i < len && std::isdigit(buf[i]); ++i)
-    result = result * 10 + FXSYS_toDecimalDigit(buf[i]);
-
+  for (int i = 0; i < len; i++) {
+    if (buf[i] < '0' || buf[i] > '9') {
+      break;
+    }
+    result = result * 10 + buf[i] - '0';
+  }
   return result;
 }
 static CFX_WideString StringDataAdd(CFX_WideString str) {
@@ -553,15 +565,26 @@ CFX_WideString CPDF_ToUnicodeMap::StringToWideString(
     const CFX_ByteStringC& str) {
   const FX_CHAR* buf = str.GetCStr();
   int len = str.GetLength();
-  if (len == 0)
+  if (len == 0) {
     return CFX_WideString();
-
+  }
   CFX_WideString result;
   if (buf[0] == '<') {
     int byte_pos = 0;
     FX_WCHAR ch = 0;
-    for (int i = 1; i < len && std::isxdigit(buf[i]); ++i) {
-      ch = ch * 16 + FXSYS_toHexDigit(buf[i]);
+    for (int i = 1; i < len; i++) {
+      int digit;
+      if (buf[i] >= '0' && buf[i] <= '9') {
+        digit = buf[i] - '0';
+      } else if (buf[i] >= 'a' && buf[i] <= 'f') {
+        digit = buf[i] - 'a' + 10;
+      } else if (buf[i] >= 'A' && buf[i] <= 'F') {
+        digit = buf[i] - 'A' + 10;
+      } else {
+        break;
+      }
+      ch = ch * 16 + digit;
+
       byte_pos++;
       if (byte_pos == 4) {
         result += ch;
@@ -571,6 +594,8 @@ CFX_WideString CPDF_ToUnicodeMap::StringToWideString(
     }
     return result;
   }
+  if (buf[0] == '(') {
+  }
   return result;
 }
 void CPDF_ToUnicodeMap::Load(CPDF_Stream* pStream) {