Reference Guide

ZCOM C I/F Library Routines
LTQDGET (3X)
Chapter 4 151
LTQDGET (3X)
NAME ltqdget – Retrieve data buffer in terminal data queue
SYNOPSIS
#include <zcom/zcomsys.h>
#include <zcom/zcomcall.h> /* if compiled with ANSI C
(recommended) */
int32 ltqdget (zap, queue, ibuf, len, rlenp)
zaddr_type *zap;
uint32 queue;
char *ibuf;
int32 len;
int32 *rlenp;
DESCRIPTION Routine ltqdget retrieves the data message stored in the data queue of
the logical terminal tables. It returns the first message in the specified
queue and releases the buffers back to the ZCOM subsystem free data
buffer pool. See the man page for ltqdput on how to store a message in
the data queue.
The data queue is designed to store a relatively large or unpredictable
amount of terminal data in a FIFO order. When compared to logical data
storage (refer to zltstore and zltup), the data queues allow terminal data
to be stored dynamically, that is, memory is used only when data is
stored. However, it is penalized by incurring more processing overhead in
data update and retrieval. In addition, access is restricted to a FIFO
order.
The libraries libzcom_c.a and libpthread.a must be linked into the calling
program by giving the options “-lzcom_c -lpthread” to cc(1) or ld(1).
Threads
Considerations
This routine may be called from a multi-threaded application using the
POSIX (1003.1c) kernel threads API package. This routine has the
following characteristics when called by a multi-threaded application:
cancellation point Thread cancellation can occur when a thread
calls this routine.