MemoryEx ASM function

[Shrek]

I'm trying to achieve the following:

Callback = function(arg1,arg2,arg3,arg4)
 return 0 
end

--[[

 -- ASM
 
 -- Function that a pointer can be obtained that will call Lua 'Callback' function.
 -- Receives 4 args and passes them to Lua function.
 -- Returns what 'Callback' returns.
 
]]

but don't really know if it's possible, the point is to get a function pointer for use with an external dll but the function calls a Lua function so Lua can be used instead of ASM.

[Shrek]

The arguments are:

LPVOID
INT
UNIT
LPVOID

[Imagine Programming]

It is possible, but it's incredibly difficult to call a Lua function from one of the ASM blocks. I've done it from an LH ASM segment once, but it involved seeking for the lua functions in memory (lua_push, lua_call etc) and it was quite the hassle.

What are you trying to do inside the callback function? You might be able to do that from within ASM as well.

[Shrek]

I'm not really sure what I'm going to do inside the function as its the behaviour callback function for that dll I emailed you about, given the possibilities for the callback appear endless I was just hoping to have the AMS library's and MemoryEx functions along with Lua available.


APM has a __DLL.NewCallback function so Im going to try making a plugin that I could then over right the Lua function name and see how things work.

[webultra]

I don't know if this can help you, it's an alien module callback example (included when you download luaforwindows):

-- using Alien to find out what the caption title of SciTE is,
-- and iterating over all top-level windows.
-- Ensure that SciTE is running first!
require 'alien'
local user = alien.load 'user32.dll'

-- these are the API calls needed. Note two NB things:
-- (1) functions dealing with text ending with 'A' are for ASCII
-- (2) need to specify abi to get proper __stdcall
user.FindWindowA:types {"string","string",abi="stdcall"}
user.GetWindowTextA:types {"int","string","int",abi="stdcall"}

find  = user.FindWindowA
gettext = user.GetWindowTextA

-- find the handle of the SciTE window using its class name
hwnd = find("SciTEWindow",nil)

-- and grab the text of that window (will be the caption)
-- create a buffer and it will be filled!
buf = alien.buffer(128)
gettext(hwnd,buf,128)
print(buf:tostring())

-- Iterating over all top-level windows.
-- again, note the abi for both EnumWindows and the callback! EnumWindows is
-- expecting an _integer_ back from the callback, where 1 means 'true' means
-- 'continue going'
function each_hwnd (hwnd,p)
    print(hwnd)
    return 1
end

each_hwnd_callback = alien.callback(each_hwnd,{"int","pointer",abi="stdcall"})

user.EnumWindows:types {"callback","pointer",abi="stdcall"}

user.EnumWindows(each_hwnd_callback,nil)