Inside Macintosh: Operating System Utilities /

Chapter 6 - Queue Utilities

Summary of the Queue Utilities

Pascal Summary

Constants

CONST    {queue types}
   vType    = 1;           {vertical retrace queue type}
   ioQType  = 2;           {file I/O or driver I/O queue type}
   drvQType = 3;           {drive queue type}
   evType   = 4;           {event queue type}
   fsQType  = 5;           {volume-control-block queue type}
   sIQType  = 6;           {slot interrupt queue type}
   dtQType  = 7;           {deferred task queue type}
   nmType   = 8;           {notification queue type}
   slpQType = 16;          {sleep queue type}

Data Types

TYPE QHdr =    {queue header record}
   RECORD
      qFlags:     Integer;       {information on queue}
      qHead:      QElemPtr;      {pointer to the first queue element}
      qTail:      QElemPtr;      {pointer to the last queue element}
   END;
   QHdrPtr = ^QHdr;
   QTypes = (  {queue types}
      dummyType,                 {reserved}
      vType,                     {vertical retrace queue type}
      ioQType,                   {file I/O or driver I/O queue type}
      drvQType,                  {drive queue type}
      evType,                    {event queue type}
      fsQType,                   {volume-control-block queue type}
      sIQType,                   {slot interrupt queue type}
      dtQType,                   {deferred task queue type}
      {nmType,}                  {notification queue type}
      {slpQType}                 {sleep queue type}
   );
   QElem =     {queue element record}
   RECORD
      CASE QTypes OF
         dtQType:    (dtQElem:   DeferredTask);    {deferred task }
                                                   { queue element}
         vType:      (vblQElem:  VBLTask);         {vertical retrace }
                                                   { queue element}
         ioQType:    (ioQElem:   ParamBlockRec);   {file I/O queue element}
         drvQType:   (drvQElem:  DrvQEl);          {drive queue element}
         evType:     (evQElem:   EvQEl);           {event queue element}
         fsQType:    (vcbQElem:  VCB);             {volume-control-block }
                                                   { queue element}
         {sIQType:   (siQElem:   SlotIntQElement;} {slot interupt }
                                                   { queue element}
         {nmType:    (nmQElem:   NMRec);}          {notification }
                                                   { queue element}
         {slpQType:  (slpQElem:  SleepQRec);}      {sleep queue element}
   END;
   QElemPtr = ^QElem;

Routines

PROCEDURE Enqueue		(qElement: QElemPtr; qHeader: QHdrPtr);
FUNCTION Dequeue		(qElement: QElemPtr; qHeader: QHdrPtr): OSErr;

C Summary

Constants

enum {      /*queue types*/
   vType    = 1,              /*vertical retrace queue type*/
   ioQType  = 2,              /*file I/O or driver I/O queue type*/
   drvQType = 3,              /*drive queue type*/
   evType   = 4,              /*event queue type*/
   fsQType  = 5,              /*volume-control-block queue type*/
   sIQType  = 6,              /*slot interrupt queue type*/
   dtQType  = 7,              /*deferred task queue type*/
};
enum {      /*value for the notification queue type*/
   nmType   = 8               /*notification queue type*/
};
enum {      /*value for the sleep queue type*/
   slpQType = 16              /*sleep queue type*/
};

Data Types

struct QHdr {  /*queue header record*/
   short          qFlags;     /*information on queue*/
   QElemPtr       qHead;      /*pointer to the first queue element*/
   QElemPtr       qTail;      /*pointer to the last queue element*/
};
typedef struct QHdr QHdr;
typedef QHdr *QHdrPtr;
typedef unsigned short QTypes;   /*queue types*/
struct QElem { /*queue element record*/
   struct QElem   *qLink;     /*pointer to the next queue element*/
   short          qType;      /*type of queue element*/
   short          qData[1];   /*variable array of data; type of data and */
                              /* length depend on the queue type, */
                              /* specified in the qType field*/
};
typedef struct QElem QElem;
typedef QElem *QElemPtr;

Routines

pascal void Enqueue		(QElemPtr qElement, QHdrPtr qHeader);
pascal OSErr Dequeue		(QElemPtr qElement, QHdrPtr qHeader);

Assembly-Language Summary

QHdr Data Structure

0	qFlags	word	information on queue
2	qHead	long	pointer to first queue entry
6	qTail	long	pointer to last queue entry

QElem Data Structure

0	qLink	long	pointer to the next queue element
4	qType	word	type of queue element
6	qData	word	variable array of data; type of data and length depend on the queue type, specified in the qType field

Result Codes

noErr	0	No error
qErr	-1	Entry is not in specified queue