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I have special problem. I use Xamarin.iOS and try to call a function of a DLL library. The original function is defined as 

LUALIB_API int luaL_loadbuffer (lua_State *L, 
                                const char *buff, 
                                size_t size,
                                const char *name)

and imported in C# as

[CLSCompliant (false)]
[DllImport(LIBNAME,CallingConvention=CallingConvention.Cdecl)]
public static extern int luaL_loadbuffer(IntPtr luaState, 
                                         string buff, 
                                         uint size, 
                                         string name);

If you can see, the library is Lua 5.1, the C# side is KeraLua, a wrapper for the library. From Lua you could call this function with a string in buff, like "a=2", which than is compiled to binary code for Lua. But you can also call this function with a binary chunk (precompiled chunk) in buff. Than buff is a byte array.

Now my problem is, that strings work perfect. But binary chunks are converted wrong. I had to convert the byte array into a string, which is in C# encoded in UTF-16. If I than call the function, this "string" is converted from UTF-16 to UTF-8. This is no problem, when buff contains text, but with binary data, the result is wrong.

An example: an integer in the binary data, which looks in the byte array as D6 21 00 00, converted to string with

StringBuilder s = new StringBuilder();
foreach (byte b in byteArray)
  s.Append((char)b);

results in D6 21 00 00. Than call the function and get in the library C3 96 21 00 00, which is obviously wrong. This is because UTF-16 D6 is in UTF-8 C3 96 and is changed while calling the function.

Coming to end, how should I define/call the function, so that this conversion didn't happen? Using Encoding.Ansi or Encoding.ASCII didn't work.

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1 回答 1

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Using .NET you can create two managed methods (either overloads or using different names by changing the DllImport attribute properties) that points to the same native function.

The first would use a string parameter. That's what you already have.

The second would use a byte[] parameter. That would ensure the data is not decoded (and modified) before going to native. Something like:

[DllImport(LIBNAME,CallingConvention=CallingConvention.Cdecl)]
public static extern int luaL_loadbuffer(IntPtr luaState, 
                                     byte[] buff, 
                                     uint size, 
                                     string name);
于 2013-05-16T12:45:24.317 回答