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utfebcdic.h: Add comment
authorKarl Williamson <public@khwilliamson.com>
Sat, 2 Mar 2013 19:33:42 +0000 (12:33 -0700)
committerKarl Williamson <public@khwilliamson.com>
Thu, 29 Aug 2013 15:56:00 +0000 (09:56 -0600)
utfebcdic.h

index 0489621..6a23433 100644 (file)
@@ -719,8 +719,14 @@ END_EXTERN_C
                                          && NATIVE_UTF8_TO_I8(c) != 0xE0)
 #define UTF8_IS_CONTINUATION(c)                ((NATIVE_UTF8_TO_I8(c) & 0xE0) == 0xA0)
 #define UTF8_IS_CONTINUED(c)           (NATIVE_UTF8_TO_I8(c) >= 0xA0)
+
 #define UTF8_IS_DOWNGRADEABLE_START(c) (NATIVE_UTF8_TO_I8(c) >= 0xC5     \
                                          && NATIVE_UTF8_TO_I8(c) <= 0xC7)
+/* Saying it this way adds a runtime test, but removes 2 run-time lookups */
+/*#define UTF8_IS_DOWNGRADEABLE_START(c)       ((c) == I8_TO_NATIVE_UTF8(0xC5)     \
+                                         || (c) == I8_TO_NATIVE_UTF8(0xC6)  \
+                                         || (c) == I8_TO_NATIVE_UTF8(0xC7))
+*/
 #define UTF8_IS_ABOVE_LATIN1(c)        (NATIVE_UTF8_TO_I8(c) >= 0xC8)
 
 /* Can't exceed 7 on EBCDIC platforms */