Make defn of OFFUNI_IS_INVARIANT common

This can be derived from other values, removing an EBCDIC dependency

1 files changed, 5 insertions, 8 deletions

diff --git a/utf8.h b/utf8.h
index 2402c6fa72..4cf52e45d2 100644
--- a/utf8.h
+++ b/utf8.h
@@ -274,14 +274,6 @@ platforms.  FF signals to use 13 bytes for the encoded character.  This breaks
 the paradigm that the number of leading bits gives how many total bytes there
 are in the character.
 
-=cut
-*/
-
-/* Is the representation of the Unicode code point 'cp' the same regardless of
- * being encoded in UTF-8 or not? */
-#define OFFUNI_IS_INVARIANT(cp)     isASCII(cp)
-
-/*
 =for apidoc Am|bool|UVCHR_IS_INVARIANT|UV cp
 
 Evaluates to 1 if the representation of code point C<cp> is the same whether or
@@ -342,6 +334,11 @@ C<cp> is Unicode if above 255; otherwise is platform-native.
             (((NATIVE_UTF8_TO_I8(c) & UTF_IS_CONTINUATION_MASK)             \
                                                 == UTF_CONTINUATION_MARK)))
 
+/* Is the representation of the Unicode code point 'cp' the same regardless of
+ * being encoded in UTF-8 or not? This is a fundamental property of
+ * UTF-8,EBCDIC */
+#define OFFUNI_IS_INVARIANT(c) (((WIDEST_UTYPE)(c)) < UTF_CONTINUATION_MARK)
+
 /* Internal macro to be used only in this file to aid in constructing other
  * publicly accessible macros.
  * The number of bytes required to express this uv in UTF-8, for just those