private static IntPtr DoCreateBuffer(string encoding)
{
IntPtr buffer;
switch (encoding)
{
case "c":
case "C":
buffer = Marshal.AllocHGlobal(4); // note that libffi expects buffers to be at least as big as a word
break;
case "s":
case "S":
buffer = Marshal.AllocHGlobal(4);
break;
case "i":
case "I":
case "l":
case "L":
buffer = Marshal.AllocHGlobal(4);
break;
case "q":
case "Q":
buffer = Marshal.AllocHGlobal(8);
break;
case "f":
buffer = Marshal.AllocHGlobal(Marshal.SizeOf(typeof(float)));
break;
case "d":
buffer = Marshal.AllocHGlobal(Marshal.SizeOf(typeof(double)));
break;
case "v":
case "Vv":
buffer = IntPtr.Zero;
break;
case "@":
case "@?":
case "#":
case ":":
buffer = Marshal.AllocHGlobal(Marshal.SizeOf(typeof(IntPtr)));
break;
default:
char type = DoGetEncodingType(encoding);
if (type == '^' || type == '*' || type == '[' || type == '(') // xxx*, char*, array, union
{
buffer = Marshal.AllocHGlobal(Marshal.SizeOf(typeof(IntPtr)));
}
else if (type == '{')
{
int i = encoding.IndexOf('=');
if (i >= 0)
{
string sname = encoding.Substring(1, i - 1);
Type stype;
if (TypeEncoder.TryGetStruct(sname, out stype))
{
int bytes = Marshal.SizeOf(stype);
buffer = Marshal.AllocHGlobal(bytes);
}
else
{
throw new InvalidCallException("Don't know how to marshal " + sname + " to a native type. Is it marked with RegisterAttribute?");
}
}
else
{
throw new InvalidCallException("'" + encoding + "' doesn't have a struct name.");
}
}
else
{
throw new InvalidCallException("Don't know how to marshal " + encoding + " to a native type.");
}
break;
}
return(buffer);
}
// Return an ffi_type* which will be used when values of the encoding
// type are marshaled through libffi.
public static IntPtr GetFfiType(Type type)
{
string encoding = TypeEncoder.Encode(type);
return(DoGetFfiType(encoding));
}