Lua的全局状态机

LUA_API lua_State *lua_newstate (lua_Alloc f, void *ud) {
  int i;
  lua_State *L;
  global_State *g;
  LG *l = cast(LG *, (*f)(ud, NULL, LUA_TTHREAD, sizeof(LG)));
  if (l == NULL) return NULL;
  L = &l->l.l;
  g = &l->g;
  L->tt = LUA_VTHREAD;
  g->currentwhite = bitmask(WHITE0BIT);
  L->marked = luaC_white(g);
  preinit_thread(L, g);
  g->allgc = obj2gco(L);  /* by now, only object is the main thread */
  L->next = NULL;
  incnny(L);  /* main thread is always non yieldable */
  g->frealloc = f;
  g->ud = ud;
  g->warnf = NULL;
  g->ud_warn = NULL;
  g->mainthread = L;
  g->seed = luai_makeseed(L);
  g->gcrunning = 0;  /* no GC while building state */
  g->strt.size = g->strt.nuse = 0;
  g->strt.hash = NULL;
  setnilvalue(&g->l_registry);
  g->panic = NULL;
  g->gcstate = GCSpause;
  g->gckind = KGC_INC;
  g->gcstopem = 0;
  g->gcemergency = 0;
  g->finobj = g->tobefnz = g->fixedgc = NULL;
  g->firstold1 = g->survival = g->old1 = g->reallyold = NULL;
  g->finobjsur = g->finobjold1 = g->finobjrold = NULL;
  g->sweepgc = NULL;
  g->gray = g->grayagain = NULL;
  g->weak = g->ephemeron = g->allweak = NULL;
  g->twups = NULL;
  g->totalbytes = sizeof(LG);
  g->GCdebt = 0;
  g->lastatomic = 0;
  setivalue(&g->nilvalue, 0);  /* to signal that state is not yet built */
  setgcparam(g->gcpause, LUAI_GCPAUSE);
  setgcparam(g->gcstepmul, LUAI_GCMUL);
  g->gcstepsize = LUAI_GCSTEPSIZE;
  setgcparam(g->genmajormul, LUAI_GENMAJORMUL);
  g->genminormul = LUAI_GENMINORMUL;
  for (i=0; i < LUA_NUMTAGS; i++) g->mt[i] = NULL;
  if (luaD_rawrunprotected(L, f_luaopen, NULL) != LUA_OK) {
    /* memory allocation error: free partial state */
    close_state(L);
    L = NULL;
  }
  return L;
}