make To/From8bit() inline for performance reasons

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@47578 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/unichar.h

@@ -137,8 +137,27 @@ public:
 
 
 private:
-    static value_type From8bit(char c);
-    static char To8bit(value_type c);
+    // notice that we implement these functions inline for 7-bit ASCII
+    // characters purely for performance reasons
+    static value_type From8bit(char c)
+    {
+        if ( (unsigned char)c < 0x80 )
+            return c;
+
+        return FromHi8bit(c);
+    }
+
+    static char To8bit(value_type c)
+    {
+        if ( c < 0x80 )
+            return c;
+
+        return ToHi8bit(c);
+    }
+
+    // helpers of the functions above called to deal with non-ASCII chars
+    static value_type FromHi8bit(char c);
+    static char ToHi8bit(value_type c);
 
 private:
     value_type m_value;