flag_buf_ptr
memcpy(flag_buf_ptr(tb, tb->used), flags, space);
memset(flag_buf_ptr(tb, tb->used), flags[0], space);
memset(flag_buf_ptr(tb, tb->used), TTY_NORMAL, space);
f = flag_buf_ptr(head, head->lookahead);
f = flag_buf_ptr(head, head->read);
*flag_buf_ptr(tb, tb->used) = flag;