using System;
using System.Reflection;
using System.Reflection.Emit;
using System.Runtime.InteropServices;
using System.Threading;
namespace Python.Runtime
{
///
/// Provides support for calling native code indirectly through
/// function pointers. Most of the important parts of the Python
/// C API can just be wrapped with p/invoke, but there are some
/// situations (specifically, calling functions through Python
/// type structures) where we need to call functions indirectly.
/// This class uses Reflection.Emit to generate IJW thunks that
/// support indirect calls to native code using various common
/// call signatures. This is mainly a workaround for the fact
/// that you can't spell an indirect call in C# (but can in IL).
/// Another approach that would work is for this to be turned
/// into a separate utility program that could be run during the
/// build process to generate the thunks as a separate assembly
/// that could then be referenced by the main Python runtime.
///
internal class NativeCall
{
[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
private delegate void Void_1_Delegate(IntPtr a1);
[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
private delegate int Int_3_Delegate(IntPtr a1, IntPtr a2, IntPtr a3);
public static void Void_Call_1(IntPtr fp, IntPtr a1)
{
var d = GetDelegate(fp);
d(a1);
}
public static IntPtr Call_3(IntPtr fp, IntPtr a1, IntPtr a2, IntPtr a3)
{
var d = GetDelegate(fp);
return d(a1, a2, a3);
}
public static int Int_Call_3(IntPtr fp, IntPtr a1, IntPtr a2, IntPtr a3)
{
var d = GetDelegate(fp);
return d(a1, a2, a3);
}
private static T GetDelegate(IntPtr fp) where T: Delegate
{
// Use Marshal.GetDelegateForFunctionPointer<> directly after upgrade the framework
return (T)Marshal.GetDelegateForFunctionPointer(fp, typeof(T));
}
}
}