ACC Programmer's Reference Guide

ZCOM C I/F Library Routines
ZREAD (3X)
Chapter 4298
PAR AMETER S
zap Pointer to program ZCOM address. Source to get input
messages.
mode ZcREAD_W_WAIT (0) - Read with wait.
The ztimr() call can be used to set a timeout period that will
cause the zread() call to unsuspend and continue after the
timeout period has elapsed.
ZcREAD_WO_WAIT (1) - Read without wait.
Note: If mode = 0, the program is suspended until there is a
message on the input queue. If mode = 1, and there is no
message on the queue, error ZENODATA (-24) is returned.
Otherwise, the message is placed in ibuf.
If bit ZCOM_ZREAD_SHARE (0x2000) is set, the input may
be shared by multiple processes. This allows multiple
processes to read (and wait) on the same ZLU. When a
message arrives, only one of the waiting processes will return
with the data.
If bit ZCOM_ZREAD_QUIET (0x4000) is set, the automatic
response mechanism is suppressed. Normally, when a
message is sent (e.g., by zsend(3X)) with a mode requesting
response, a response is generated automatically when the
message is read by zread. This bit is used to suppress this
response, and the caller is responsible for checking the
request mode and sending a response back to the originator if
necessary. This feature is intended for multiplexing programs
and should be used with care. This bit is not used in
zpeek(3X).
mhp
(Return
Param)
Pointer to message header. It is the message header received
with the data buffer. NULL may be specified if the caller does
not require the returned message header. It is described in
the subsection on ‘Message Header’ in the Multiprotocol ACC
Programmers’ Reference Guide. See the data structure
zmhd_type in zcomsys.h for more detail.
ibuf (Return
Param)
Buffer for the received data.
len Maximum length in bytes of the buffer ibuf.