get_arg
void *get_arg;
|| ASYNC_WAIT_CTX_get_callback(waitctx, &get_callback, &get_arg)
|| get_arg != (void *)&set_arg
|| (*get_callback)(get_arg) != 1
get_arg(c);
get_arg(c);
return get_arg(offset);
return get_arg(offset) | ((offset >> 16) & 0xff) << 8;