Dequeue
De queue Remove an element from a queue
#include <OSUtils.h> Operating System Utilities
OSErr De queue(qEntry, theQueue ); QElemPtr qEntry ; address of a queue element QHdrPtr theQueue ; address of a queue header De queue removes an element from a queue, adjusting the queue links to
bypass the element. The element itself is not de allocated.
qEntry is the address of a variable-length QElem structure whose size and contents depend upon the type of queue. This must be the same as a
qEntry value used in a previous call to En queue.
theQueue is the address of a 10-byte QHdr structure. This structure contains information about the queue-some type-specific flags and pointers to
the first and last element in the queue.
qErr (-1) Entry not in specified queue
Notes: De queue is used to remove any element from a queue. The caller is
responsible for deallocating the space used by the queue element (if that
memory needs to be freed).
The De queue routine turns off interrupts for critical sections of its code. This makes it ideal for queue management for interrupt- driven programs
which need to be concerned about simultaneous execution and deadlock.
An example of queue usage is contained in En queue.