Minetest FFI mapgen

diff --git a/src/script/lua_api/l_vmanip.cpp b/src/script/lua_api/l_vmanip.cpp
index ca837b6..abf3353 100644
--- a/src/script/lua_api/l_vmanip.cpp
+++ b/src/script/lua_api/l_vmanip.cpp
@@ -30,6 +30,14 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "mapgen/mapgen.h"
 #include "voxelalgorithms.h"

+#if USE_LUAJIT
+extern "C" void VoxelManip_get(void **lvmp, MapNode **data)
+{
+   MMVManip *vm = (*(LuaVoxelManip **)lvmp)->vm;
+   *data = vm->m_data;
+}
+#endif
+
 // garbage collector
 int LuaVoxelManip::gc_object(lua_State *L)
 {

---------------------------------------------------------
-- File: testmod/init.lua (added to secure.trusted_mods)

local ie = minetest.request_insecure_environment()
local ffi = ie.require("ffi")
ffi.cdef[[
typedef struct {
    uint16_t id;
    uint8_t param1;
    uint8_t param2;
} MapNode;
void VoxelManip_get(void **vm, MapNode **data);
]]

local c_air = minetest.get_content_id("air")
local c_ice = minetest.get_content_id("default:ice")
local avg = 0

function generate_this_stuff(minp, maxp, seed)
    local uffi = false

    local t1 = os.clock()
    local sidelen1d = maxp.x - minp.x + 1
    local sidelen3d = {x=sidelen1d, y=sidelen1d, z=sidelen1d}

    local vm, emin, emax = minetest.get_mapgen_object("voxelmanip")
    local area = VoxelArea:new{MinEdge=emin, MaxEdge=emax}
    local data

    if uffi then
        local __data = ffi.new("MapNode*[0]")
        ffi.C.VoxelManip_get(vm, __data)
        data = __data[0]
    else
        data = vm:get_data()
    end

    local nvals_caves = minetest.get_perlin_map({
        offset = 0,
        scale = 1,
        spread = {x=64, y=64, z=64},
        octaves = 4,
        seed = -11842,
        persist = 0.4,
        flags = "eased"
    }, sidelen3d):get3dMap_flat(minp)

    local nixyz = 1
    for z = minp.z, maxp.z do
    for y = minp.y, maxp.y do
        local vi = area:index(minp.x, y, z)
        for x = minp.x, maxp.x do
            local cave = nvals_caves[nixyz] + math.max(-1, y / 32)

            if uffi then
                if cave < 0 then
                    data[vi].id = c_ice
                else
                    data[vi].id = c_air
                end
                data[vi].param2 = 0
            else
                if cave < 0 then
                    data[vi] = c_ice
                else
                    data[vi] = c_air
                end
            end

            nixyz = nixyz + 1
            vi = vi + 1
        end
    end
    end

    if not uffi then
        vm:set_data(data)
        vm:set_lighting({day=0, night=0})
    end

    vm:calc_lighting()
    vm:write_to_map()
    vm:update_liquids()
    local dtime = (os.clock() - t1) * 1000
    avg = (avg == 0) and dtime or (avg * 25 + dtime) / 26


    minetest.log("action", "this = " ..
        math.ceil(dtime) .. " ms, avg = " ..
        math.ceil(avg) .. " ms")
end

minetest.after(0, table.insert,
    minetest.registered_on_generateds, 1, generate_this_stuff)