Xinu7/man/man3/queue.doc

QUEUE(3)            Xinu Programmer's Manual             QUEUE(3)



NAME
     queue - q-structure predicates and list manipulation pro-
     cedures

SYNOPSIS
     #include <q.h>

     int enqueue(proc, tail)
     int dequeue(proc)
     int firstid(head)
     int firstkey(head)
     int getfirst(head)
     int getlast(tail)
     int insert(proc, head, key)
     int insertd(proc, head, key)
     Bool isempty(head)
     int lastkey(tail)
     Bool nonempty(head)

     int head, tail;
     int proc;
     int key;

DESCRIPTION
     The _q structure holds doubly-linked lists of processes,
     including lists of processes that are ready, sleeping, and
     waiting on a semaphore.  These routines manipulate lists in
     the _q structure as follows.

     enqueue
          Add a process to a FIFO list given the process id in
          argument _p_r_o_c and the _q index of the tail of the list
          in argument _t_a_i_l.  _E_n_q_u_e_u_e returns argument _p_r_o_c to its
          caller.

     dequeue
          Remove a process from a list given the process id.  The
          list on which the process is found need not be speci-
          fied because it can be determined from the _q structure.
          _D_e_q_u_e_u_e will remove a process from both FIFO and
          ordered lists.  It returns its argument to the caller.

     firstid
          Return the process id of the first process on a list
          given the _q index of the list head in argument _h_e_a_d.

     firstkey
          Return the integer key associated with the first entry
          on a list given the _q index of the list in argument
          _h_e_a_d.

     getfirst



Version 6b               Printed 1/12/87                        1






QUEUE(3)            Xinu Programmer's Manual             QUEUE(3)



          Remove the first process from a list and return its
          process id given the _q index of the head of the list in
          argument _h_e_a_d.  _G_e_t_f_i_r_s_t returns EMPTY if the list is
          empty, and a process id otherwise.

     getlast
          Remove the last process on a list and return its pro-
          cess id given the _q index of the tail of the list in
          argument _t_a_i_l.  _G_e_t_l_a_s_t returns EMPTY if the list is
          empty, and a process id otherwise.

     insert
          Insert a process into an ordered list given the process
          id in argument _p_r_o_c, the _q index of the head of the
          list in argument _h_e_a_d, and an integer key for the pro-
          cess in argument _k_e_y.  Ordered lists are always ordered
          by increasing key values.  _I_n_s_e_r_t returns OK.

     insertd
          Insert a process in a delta list given the process id
          in argument _p_r_o_c, the _q index of the head of the list
          in argument _h_e_a_d, and an integer key in argument _k_e_y.
          _I_n_s_e_r_t_d returns OK.

     isempty
          Return TRUE if there are no processes on a list, FALSE
          otherwise, given the _q index of the head of the list in
          argument _h_e_a_d.

     lastkey
          Return the key of the last process in a list given the
          _q index of the tail of the list in argument _t_a_i_l.

     nonempty
          Return TRUE if there is at least one process on a list,
          FALSE otherwise, given the _q index of the head of the
          list in argument _h_e_a_d.

BUGS
     Most of these routines do not check for valid arguments or
     valid lists.  Also, they assume interrupts are disabled when
     called, and will corrupt the list structure if the caller
     fails to disable interrupts.












Version 6b               Printed 1/12/87                        2