ffi.d

enum StrZ(alias S) = S~'\0';
alias Cdeclº(Rº, Pº...) = extern(C) Rº function(Pº);
alias Stdcallº(Rº, Pº...) = extern(Windows) Rº function(Pº);

auto cinvoke(wstring LibName, string FuncName, Rº = void, Pº...)(Pº Params) {
	alias Ptr = LibSymPtr!(LibName, FuncName);
	assert(Ptr !is null);
	return (cast(Cdeclº!(Rº, Pº)) Ptr)(Params);
};

auto pinvoke(wstring LibName, string FuncName, Rº = void, Pº...)(Pº Params) {
	alias Ptr = LibSymPtr!(LibName, FuncName);
	assert(Ptr !is null);
	return (cast(Stdcallº!(Rº, Pº)) Ptr)(Params);
};

template LibSymPtr(wstring LibName, string SymName) {
	alias LibSymPtr = S.SymPtr;
	struct S {
		static __gshared void* SymPtr;
		shared static this() {
			SymPtr = import_sym(StrZ!LibName.ptr, StrZ!SymName.ptr);
		};
	};
};

version (Windows) void* import_sym(in wchar* LibName, in char* SymName) {
	import W32_ = core.sys.windows.windows;
	import std.exception : enforce_ = enforce;
	import std.string : fromStringz_ = fromStringz;
	auto Lib = W32_.GetModuleHandleW(LibName);
	if (!Lib) {
		Lib = W32_.LoadLibraryW(LibName);
	};
	void* Ptr =  W32_.GetProcAddress(Lib, SymName);
	enforce_(Ptr !is null, `failed to import symbol `~SymName.fromStringz_);
	return Ptr;
};

unittest {
	void* Info;
	pinvoke!(`ntdll`, `LdrFindEntryForAddress`)(
		0x400000, &Info
	);
	import std.stdio;
	writeln(Info);
};