Function luaD_precall

third-party/lua-5.2.4/src/ldo.c:296–359

** returns true if function has been executed (C function) */

** returns true if function has been executed (C function)
*/
int luaD_precall (lua_State *L, StkId func, int nresults) {
  lua_CFunction f;
  CallInfo *ci;
  int n;  /* number of arguments (Lua) or returns (C) */
  ptrdiff_t funcr = savestack(L, func);
  switch (ttype(func)) {
    case LUA_TLCF:  /* light C function */
      f = fvalue(func);
      goto Cfunc;
    case LUA_TCCL: {  /* C closure */
      f = clCvalue(func)->f;
     Cfunc:
      luaD_checkstack(L, LUA_MINSTACK);  /* ensure minimum stack size */
      ci = next_ci(L);  /* now 'enter' new function */
      ci->nresults = nresults;
      ci->func = restorestack(L, funcr);
      ci->top = L->top + LUA_MINSTACK;
      lua_assert(ci->top <= L->stack_last);
      ci->callstatus = 0;
      luaC_checkGC(L);  /* stack grow uses memory */
      if (L->hookmask & LUA_MASKCALL)
        luaD_hook(L, LUA_HOOKCALL, -1);
      lua_unlock(L);
      n = (*f)(L);  /* do the actual call */
      lua_lock(L);
      api_checknelems(L, n);
      luaD_poscall(L, L->top - n);
      return 1;
    }
    case LUA_TLCL: {  /* Lua function: prepare its call */
      StkId base;
      Proto *p = clLvalue(func)->p;
      n = cast_int(L->top - func) - 1;  /* number of real arguments */
      luaD_checkstack(L, p->maxstacksize);
      for (; n < p->numparams; n++)
        setnilvalue(L->top++);  /* complete missing arguments */
      if (!p->is_vararg) {
        func = restorestack(L, funcr);
        base = func + 1;
      }
      else {
        base = adjust_varargs(L, p, n);
        func = restorestack(L, funcr);  /* previous call can change stack */
      }
      ci = next_ci(L);  /* now 'enter' new function */
      ci->nresults = nresults;
      ci->func = func;
      ci->u.l.base = base;
      ci->top = base + p->maxstacksize;
      lua_assert(ci->top <= L->stack_last);
      ci->u.l.savedpc = p->code;  /* starting point */
      ci->callstatus = CIST_LUA;
      L->top = ci->top;
      luaC_checkGC(L);  /* stack grow uses memory */
      if (L->hookmask & LUA_MASKCALL)
        callhook(L, ci);
      return 0;
    }