Inside Macintosh: Networking /

Chapter 12 - Multinode Architecture

Summary of Multinode Architecture

The multinode architecture MPP parameter block data structure and symbolic constants for routines and result codes are not defined in the MPW interface files. (The write-data structure and the address block record are defined in the MPW interface files for use with other protocols, but you can use them for multinode also.)

You must declare the MPP parameter block for multinode in your application. If you want to use the symbolic constants for the routines and result codes, you need to declare them also.

You use the Device Manager's PBControl function to call the RemoveNode and NetWrite routines from the Pascal and C languages. You must issue the AddNode routine as an immediate synchronous control call from the Pascal and C languages. You must define a function as part of your application. (See Listing 12-1 on page 12-8 for an example of how to do this in Pascal.) From assembly language, you can directly make an immed _Control trap macro call.

Pascal Summary

Constants

(Declare the following constants in your application.)

CONST
   {csCodes}
   netWrite    = 261;               {send packet through multinode}
   addNode     = 262;               {request a multinode}
   removeNode  = 263;               {remove multinode}

Data Types

The Write-Data Structure

TYPE  WDSElement = 
   RECORD
      entryLength:   Integer;
      entryPtr:      Ptr;
   END;

The Address Block Record

TYPE AddrBlock = 
   PACKED RECORD
      aNet:          Integer;    {network number for multinode}
      aNode:         Byte;       {multinode ID}
      aSocket:       Byte;       {socket number; always 0}
   END;

The Multinode Parameter Block

(Declare this data type in your application.)

TYPEMNParmType = (AddNodeParm,RemoveNodeParm);
TYPE MNParamBlock = 
   PACKED RECORD
      qLink:         QElemPtr;         {reserved}
      qType:         Integer;          {reserved}
      ioTrap:        Integer;          {reserved}
      ioCmdAddr:     Ptr;              {reserved}
      ioCompletion:  ProcPtr;          {completion routine}
      ioResult:      OSErr;            {result code}
      ioNamePtr:     StringPtr;        {reserved}
      ioVRefNum:     Integer;          {reserved}
      ioRefNum:      Integer;          {driver reference number}
      csCode:        Integer;          {call command code}
         filler1:       Byte;          {reserved}
         checkSumFlag:  Byte;          {perform checksum on datagram}
         wdsPointer:    Ptr;           {pointer to write-data structure}
         filler2:       Integer;       {reserved}
         CASE MNParmType OF
            AddNodeParm:
            (reqNodeAddr:  AddrBlock;     {preferred address requested}
             actNodeAddr:  AddrBlock;     {actual node address returned}
             recvRoutine:  ProcPtr;       {pointer to packet receive routine}
             reqCableLo:   Integer;       {preferred network range for the }
             reqCableHi:   Integer;       { node being acquired}
             reserved:     PACKED ARRAY[1..70] OF Byte);
            RemoveNodeParm:
            (nodeAddr:     AddrBlock);    {node address to be deleted}
END;
MNParmBlkPtr = ^MNParamBlock;

C Summary

Constants

(Declare the following constants in your application.)

/*csCodes*/
enum {
   netWrite       = 261,               /*send packet through multinode*/
   addNode        = 262,               /*request a multinode*/
   removeNode     = 263                /*remove multinode*/
};

Data Types

The Write-Data Structure

struct   WDSElement { 
   short    entryLength;
   Ptr      entryPtr;
} WDSElement;

The Address Block Record

struct AddrBlock { 
      short             aNet;          /*network number for multinode*/
      unsigned char     aNode;         /*multinode ID*/
      unsigned char     aSocket;       /*socket number; always 0*/
};

typedef struct AddrBlock AddrBlock;

The MPP Parameter Block for Multinode

(Declare this data type in your application.)

typedef struct {
   MPPATPHeader
      char              filler1;       /*reserved*/
      unsigned char     checkSumFlag;  /*perform checksum on datagram*/
      Ptr               wdsPointer;    /*pointer to write-data structure*/
      char              filler2[2];    /*reserved*/
      union {
         AddrBlock      reqNodeAddr;   /*preferred address requested*/
         AddrBlock      nodeAddr;      /*node address to be deleted*/
               } MNaddrs;
      AddrBlock      actNodeAddr;      /*actual node address acquired*/
      Ptr            recvRoutine;      /*address of packet receive routine*/
      short          reqCableLo;       /*preferred network range for the */
      short          reqCableHi;       /* node being acquired*/
      char           reserved[70];
} MNParamBlock;
typedef MNParamBlock*MNParmBlkPtr;

Assembly-Language Summary

MPP Parameter Block Common Fields for Multinode Routines

0	qLink	long	reserved
4	qType	word	reserved
6	ioTrap	word	reserved
8	ioCmdAddr	long	reserved
12	ioCompletion	long	address of completion routine
16	ioResult	word	result code
18	ioNamePtr	long	reserved
22	ioVRefNum	word	reserved
24	ioRefNum	word	driver reference number

AddNode

26	csCode	word	routine selector; always 262 for this routine
36	reqNodeAddr	long	requested multinode address
40	actNodeAddr	long	actual multinode address assigned
44	recvRoutine	long	address of the application's receive routine
48	reqCableLo	word	beginning of requested network number range for the multinode
50	reqCableHi	word	end of the requested network number range for the multinode
52	reserved	array	70 reserved bytes required by the .MPP driver

Parameter Variant

(Note that to execute the AddNode routine from assembly language, you call the _Control trap macro and issue the routine request as an immediate call.)

RemoveNode

26	csCode	word	routine selector; always 263 for this routine
36	nodeAddr	long	actual multinode address assigned

Parameter Variant

NetWrite

26	csCode	word	routine selector; always 261 for this routine
29	checkSumFlag	byte	a flag indicating whether the checksum should be calculated or the existing checksum left unmodified
30	wdsPointer	long	a pointer to the write-data structure for this routine

Parameter Variant

Result Codes

noErr	0	No error
paramErr	-50	Bad parameter value
ddpLenErr	-92	Datagram is too long
noBridgeErr	-93	No router found
excessCollsns	-95	Excessive collisions on write
tryAddNodeAgainErr	-1021	The .MPP driver was not able to add node; try again
mnNotSupported	-1022	Multinode is not supported by the current AppleTalk connection file of type 'adev'
noMoreMultiNodes	-1023	No node address is available on the network