lua_State *luaE_newthread (lua_State *L) {
  lua_State *L1 = mallocstate(L);
  luaC_link(L, valtogco(L1), LUA_TTHREAD);
  preinit_state(L1);
  L1->l_G = L->l_G;
  stack_init(L1, L);  /* init stack */
  setobj2n(gt(L1), gt(L));  /* share table of globals */
  return L1;
}

void luaF_close (lua_State *L, StkId level) {
  UpVal *p;
  while ((p = ngcotouv(L->openupval)) != NULL && p->v >= level) {
    setobj2n(&p->value, p->v);  /* save current value (write barrier) */
    p->v = &p->value;  /* now current value lives here */
    L->openupval = p->next;  /* remove from `open' list */
    luaC_link(L, valtogco(p), LUA_TUPVAL);
  }
}

lua_State *luaE_newthread (lua_State *L) {
  lua_State *L1 = tostate(luaM_malloc(L, state_size(lua_State)));
  luaC_link(L, obj2gco(L1), LUA_TTHREAD);
  preinit_state(L1, G(L));
  stack_init(L1, L);  /* init stack */
  setobj2n(L, gt(L1), gt(L));  /* share table of globals */
  L1->hookmask = L->hookmask;
  L1->basehookcount = L->basehookcount;
  L1->hook = L->hook;
  resethookcount(L1);
  lua_assert(iswhite(obj2gco(L1)));
  return L1;
}

LUA_API void lua_pushcclosure (lua_State *L, lua_CFunction fn, int n) {
  Closure *cl;
  lua_lock(L);
  luaC_checkGC(L);
  api_checknelems(L, n);
  cl = luaF_newCclosure(L, n);
  cl->c.f = fn;
  L->top -= n;
  while (n--)
    setobj2n(&cl->c.upvalue[n], L->top+n);
  setclvalue(L->top, cl);
  api_incr_top(L);
  lua_unlock(L);
}

lua_State *luaE_newthread (lua_State *L) {
  lua_State *L1 = tostate(luaM_malloc(L, state_size(lua_State)));
  luaC_link(L, obj2gco(L1), LUA_TTHREAD);
  setthvalue(L, L->top, L1); /* put thread on stack */
  incr_top(L);
  preinit_state(L1, G(L));
  stack_init(L1, L);  /* init stack */
  setobj2n(L, gt(L1), gt(L));  /* share table of globals */
  L1->hookmask = L->hookmask;
  L1->basehookcount = L->basehookcount;
  L1->hook = L->hook;
  resethookcount(L1);
  lua_assert(!isdead(G(L), obj2gco(L1)));
  L->top--; /* remove thread from stack */
  return L1;
}

LUA_API void lua_pushcclosure (lua_State *L, lua_CFunction fn, int n) {
  lua_lock(L);
  if (n == 0) {
    setfvalue(L->top, fn);
  }
  else {
    Closure *cl;
    api_checknelems(L, n);
    api_check(L, n <= MAXUPVAL, "upvalue index too large");
    luaC_checkGC(L);
    cl = luaF_newCclosure(L, n);
    cl->c.f = fn;
    L->top -= n;
    while (n--)
      setobj2n(L, &cl->c.upvalue[n], L->top + n);
    setclCvalue(L, L->top, cl);
  }
  api_incr_top(L);
  lua_unlock(L);
}

lua_State *luaE_newthread (lua_State *L) {
  lua_State *L1 = mallocstate(L);
  luaC_link(L, valtogco(L1), LUA_TTHREAD);
  preinit_state(L1);
  L1->l_G = L->l_G;
#if LUA_REFCOUNT
  L1->gclist_head.next = (GCObject*)&L->gclist_tail;
  L1->gclist_head.prev = NULL;
  L1->gclist_tail.next = NULL;
  L1->gclist_tail.prev = (GCObject*)&L->gclist_head;
  L1->gclist_head.tt = LUA_TNIL;
  L1->gclist_head.marked = 0;
  L1->gclist_head.ref = 0;
  L1->gclist_tail.tt = LUA_TNIL;
  L1->gclist_tail.marked = 0;
  L1->gclist_tail.ref = 0;
  L1->ref = 0;
#endif LUA_REFCOUNT
  stack_init(L1, L);  /* init stack */
  setobj2n(gt(L1), gt(L));  /* share table of globals */
  return L1;
}