fix base64 computation for strings whose length modulo 3 is 2 (patch 1665520; bug 1661616) [backport from HEAD]

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_2_8_BRANCH@44660 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

docs/changes.txt

@@ -107,6 +107,7 @@ All:
 - Implemented background colour in wxRichTextCtrl.
 - Fixed crashes in helpview when opening a file.
 - Fixed detection of number of processors under Linux 2.6
+- Fixed Base64 computation in wxHTTP (p_michalczyk)
 
 wxMSW
 

src/common/http.cpp

@@ -139,7 +139,7 @@ wxString wxHTTP::GenerateAuthString(const wxString& user, const wxString& pass)
         if (len == 1) {
             buf << wxString::Format(wxT("%c="), base64[(from[0] << 4) & 0x30]);
         } else {
-            buf << wxString::Format(wxT("%c%c"), base64[(from[0] << 4) & 0x30] + ((from[1] >> 4) & 0xf), base64[(from[1] << 2) & 0x3c]);
+            buf << wxString::Format(wxT("%c%c"), base64[((from[0] << 4) & 0x30) | ((from[1] >> 4) & 0xf)], base64[(from[1] << 2) & 0x3c]);
         }
         buf << wxString::Format(wxT("="));
     }