A new hard disk device with removable media has been added to a MINIX 3 system. This device must spin up to speed every time the media are changed, and the spin up time is quite long. It is anticipated media changes will be made frequently while the system is running. Suddenly the waitfor routine in at
wini.c is unsatisfactory. Design a new waitfor routine in which, if the bit pattern being awaited is not found after 1 second of busy waiting, a phase will be entered in which the disk driver will sleep for 1 second, test the port, and go back to sleep for another second until either the soughtfor pattern is found or the preset TIMEOUT period expires.