jsr    r0,arg2 / get arguments special and name
        tst    mnti / is the i-number of the cross device file zero?
        bne    errora / no, error
        jsr    r0,getspl / get special files device number in r1
        mov    (sp)+,u.namep / put the name of file to be placed on the
                             / device
        mov    r1,-(sp) / save the device number
        jsr    r0,namei / get the i-number of the file
               br errora
        mov    r1,mnti / put it in mnti
1:
        tstb   sb1+1 / is 15th bit of I/O queue entry for dismountable
                     / device set?
        bne    1b / (inhibit bit) yes, skip writing
        mov    (sp),mntd / no, put the device number in mntd
        movb   (sp),sb1 / put the device number in the lower byte of the
                        / I/O queue entry
        mov    (sp)+,cdev / put device number in cdev
        bis    $2000,sb1 / set the read bit
        jsr    r0,ppoke / read in entire file system
1:
        tstb   sb1+1 / done reading?
        bne    1b / no, wait
        br     sysreta / yes

sysumount: / special dismount file system
        jsr    r0,arg; u.namep / point u.namep to special
        jsr    r0,getspl / get the device number in r1
        cmp    r1,mntd / is it equal to the last device mounted?
        bne    errora / no error
1:
        tstb   sb1+1 / yes, is the device still doing I/O (inhibit
                     / bit set)?
        bne    1b / yes, wait
        clr    mntd / no, clear these
        clr    mnti
        br     sysreta / return

getspl: / get device number from a special file name
        jsr    r0,namei / get the i-number of the special file
               br errora / no such file
        sub    $4,r1 / i-number-4 rk=1,tap=2+n
        ble    errora / less than 0?  yes, error
        cmp    r1,$9. / greater than 9  tap 7
        bgt    errora / yes, error
        rts    r0 / return with device number in r1

errora:
        jmp    error / see 'error' routine

sysreta:
        jmp    sysret / see 'sysret' routine