HP UX 11i v1 I/O Cards manual Messages, Mode ZcREADWWAIT 0 Read with wait, Used in zpeek3X

ZCOM C I/F Library Routines

ZREAD (3X)

PARAMETERS

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.

270 Chapter 4