optimize isSpace for negative 8 bit bytes

bb383e22 · Dick Hollenbeck · 56796a95 · bb383e22
Commit bb383e22 authored Oct 08, 2012 by Dick Hollenbeck
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dsnlexer.cpp common/dsnlexer.cpp +3 -1

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--- a/common/dsnlexer.cpp
+++ b/common/dsnlexer.cpp
@@ -375,7 +375,9 @@ int DSNLEXER::NeedNUMBER( const char* aExpectation ) throw( IO_ERROR )
 */
 static bool isSpace( int cc )
 {
-    if( cc <= ' ' )
+    // cc was signed extended from signed char, so it is often negative.
+    // Treat negative as large positive to exclude rapidly.
+    if( unsigned( cc ) <= ' ' )
    {
        switch( cc )
        {