core: fixed some (Chinese) encoding on Windows

Author: Arnaud Bouchez

src/core/mormot.core.os.windows.inc

@@ -177,14 +177,36 @@ end;
 const
   DefaultCharVar: AnsiChar = '?';
 
+function FullCodePage(CodePage: cardinal): boolean; {$ifdef HASINLINE} inline; {$endif}
+begin
+  case CodePage of
+    50220 .. 50229, 54936, 57002 .. 57011, 65000, CP_UTF8:
+      result := true; // as required by the Windows API
+  else
+    result := false;
+  end;
+end;
+
 function Unicode_AnsiToWide(A: PAnsiChar; W: PWideChar; LA, LW, CodePage: PtrInt): integer;
+var
+  flags: cardinal;
 begin
-  result := MultiByteToWideChar(CodePage, MB_PRECOMPOSED, A, LA, W, LW);
+  if FullCodePage(CodePage) then
+    flags := 0
+  else
+    flags := MB_PRECOMPOSED;
+  result := MultiByteToWideChar(CodePage, flags, A, LA, W, LW);
 end;
 
 function Unicode_WideToAnsi(W: PWideChar; A: PAnsiChar; LW, LA, CodePage: PtrInt): integer;
+var
+  defchar: PAnsiChar;
 begin
-  result := WideCharToMultiByte(CodePage, 0, W, LW, A, LA, @DefaultCharVar, nil);
+  if FullCodePage(CodePage) then
+    defchar := nil
+  else
+    defchar := @DefaultCharVar;
+  result := WideCharToMultiByte(CodePage, 0, W, LW, A, LA, defchar, nil);
 end;
 
 function Win32Utf8ToAnsi(P: pointer; L, CP: integer; var A: RawByteString): boolean;

src/mormot.commit.inc

@@ -1 +1 @@
-'2.3.9541'
+'2.3.9542'