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Inside Macintosh: Interapplication Communication /

Chapter 11 - Program-to-Program Communications Toolbox / PPC Toolbox Reference

PPC Toolbox Routines / Opening and Closing a Port

PPCOpen

You open a port using the PPCOpen function.

FUNCTION PPCOpen (pb: PPCOpenPBPtr; async: Boolean): OSErr;

pb

A pointer to a PPCOpen parameter block.

async

A value that specifies whether the function is to be executed asynchronously (TRUE) or synchronously (FALSE).

-->	ioCompletion	PPCCompProcPtr	Address of a completion routine
<--	ioResult	OSErr	Result code
<--	portRefNum	PPCPortRefNum	Port reference number of port opened
-->	serviceType	PPCServiceType	Service type requested--must be ppcServiceRealTime
-->	resFlag	SignedByte	Reserved field--must be 0
-->	portName	PPCPortPtr	Pointer to a PPCPortRec
-->	locationName	LocationNamePtr	Pointer to a LocationNameRec
-->	networkVisible	Boolean	Make this port network visible
<--	nbpRegistered	Boolean	Port location was registered on the network

DESCRIPTION

If your application calls the PPCOpen function asynchronously, you must specify in the ioCompletion field either the address of a completion routine or NIL. If you set ioCompletion to NIL, you should poll the ioResult field of the PPC parameter block (from your application's main event loop) to determine whether the PPC Toolbox has completed the requested operation. A value in the ioResult field other than 1 indicates that the call is complete. Note that it is unsafe to poll the ioResult field at interrupt time since the PPC Toolbox may be in the process of completing a call. See "PPC Toolbox Calling Conventions" beginning on page 11-14 for detailed information.

If you call the PPCOpen function asynchronously, you must not change any of the fields in the parameter block until the call completes. The port name and location name pointed to by the PPCOpen parameter block record are owned by the PPC Toolbox until the call completes. These objects must not be deallocated or moved in memory while the call is in progress.

The portRefNum field returns the PPC port identifier. Use this port reference number to initiate a session for this particular port. Set the serviceType field to indicate that this port accepts sessions in real time. For System 7, this field must always be set to the ppcServiceRealTime constant. You must set the resFlag field to 0.

The portName field must contain a pointer to a PPC port record that specifies the name of the PPC port to be opened.

The locationName field should contain a pointer to a location name record that designates the location of the PPC port to be opened. If the locationName pointer is NIL, then the default name PPC Toolbox is used. If a location name record is used, then the locationKindSelector field in the location name record must be ppcNBPTypeLocation, and an alias location name specified by the location name record's nbpType field is used.

The networkVisible field indicates whether the port should be made visible (for browsing as well as incoming network requests). If you specify FALSE, this port is not visible in the listing of available ports across a network (although it is still included within the local machine's listing of available ports).

The nbpRegistered field returns TRUE if the location name specified was registered on the network.

ASSEMBLY-LANGUAGE INFORMATION

The trap macro and routine selector for the PPCOpen function are

Trap macro	Selector
_PPC	$0001

The registers on entry and exit for this routine are

Registers on entry
A0	Pointer to a parameter block
D0	Selector (1)

Registers on exit
D0	Result code

RESULT CODES

noErr	0	No error
notInitErr	-900	PPC Toolbox has not been initialized yet
nameTypeErr	-902	Invalid or inappropriate locationKindSelector in location name
noPortErr	-903	Unable to open port or bad port reference number
noGlobalsErr	-904	System unable to allocate memory, critical error
badReqErr	-909	Bad parameter or invalid state for this operation
portNameExistsErr	-910	Another port is already open with this name
badPortNameErr	-919	PPC port record is invalid
badServiceMethodErr	-930	Service method is other than ppcServiceRealTime
badLocNameErr	-931	Location name is invalid
nbpDuplicateName	-1027	Location name represents a duplicate on this computer

SEE ALSO

For an example of the use of the PPCOpen function, see Listing 11-2 on page 11-21.