.TH QUEUE 3 .SH NAME queue - q-structure predicates and list manipulation procedures .SH SYNOPSIS .B #include <q.h> .PP .nf .B int enqueue(proc, tail) .B int dequeue(proc) .B int firstid(head) .B int firstkey(head) .B int getfirst(head) .B int getlast(tail) .B int insert(proc, head, key) .B int insertd(proc, head, key) .B Bool isempty(head) .B int lastkey(tail) .B Bool nonempty(head) .br .sp .B int head, tail; .br .B int proc; .br .B int key; .br .SH DESCRIPTION The \f2q\f1 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 \f2q\f1 structure as follows. .TP .B enqueue Add a process to a FIFO list given the process id in argument \f2proc\f1 and the \f2q\f1 index of the tail of the list in argument \f2tail\f1. \f2Enqueue\f1 returns argument \f2proc\f1 to its caller. .TP .B dequeue Remove a process from a list given the process id. The list on which the process is found need not be specified because it can be determined from the \f2q\f1 structure. \f2Dequeue\f1 will remove a process from both FIFO and ordered lists. It returns its argument to the caller. .TP .B firstid Return the process id of the first process on a list given the \f2q\f1 index of the list head in argument \f2head\f1. .TP .B firstkey Return the integer key associated with the first entry on a list given the \f2q\f1 index of the list in argument \f2head\f1. .TP .B getfirst Remove the first process from a list and return its process id given the \f2q\f1 index of the head of the list in argument \f2head\f1. \f2Getfirst\f1 returns EMPTY if the list is empty, and a process id otherwise. .TP .B getlast Remove the last process on a list and return its process id given the \f2q\f1 index of the tail of the list in argument \f2tail\f1. \f2Getlast\f1 returns EMPTY if the list is empty, and a process id otherwise. .TP .B insert Insert a process into an ordered list given the process id in argument \f2proc\f1, the \f2q\f1 index of the head of the list in argument \f2head\f1, and an integer key for the process in argument \f2key\f1. Ordered lists are always ordered by increasing key values. \f2Insert\f1 returns OK. .TP .B insertd Insert a process in a delta list given the process id in argument \f2proc\f1, the \f2q\f1 index of the head of the list in argument \f2head\f1, and an integer key in argument \f2key\f1. \f2Insertd\f1 returns OK. .TP .B isempty Return TRUE if there are no processes on a list, FALSE otherwise, given the \f2q\f1 index of the head of the list in argument \f2head\f1. .TP .B lastkey Return the key of the last process in a list given the \f2q\f1 index of the tail of the list in argument \f2tail\f1. .TP .B nonempty Return TRUE if there is at least one process on a list, FALSE otherwise, given the \f2q\f1 index of the head of the list in argument \f2head\f1. .SH 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.