Inside Macintosh: Processes

Chapter 4 - Vertical Retrace Manager

Summary of the Vertical Retrace Manager

Pascal Summary

Data Type

TYPE VBLTask   =              {VBL queue element}
   RECORD
      qLink:      QElemPtr;   {next entry in vertical retrace queue}
      qType:      Integer;    {queue type}
      vblAddr:    ProcPtr;    {pointer to task procedure}
      vblCount:   Integer;    {interrupts until next execution}
      vblPhase:   Integer;    {task phase}
   END;

Vertical Retrace Manager Routines

Slot-Based Installation and Removal Routines

FUNCTION SlotVInstall(vblTaskPtr: QElemPtr; theSlot: Integer): OSErr;
FUNCTION SlotVRemove(vblTaskPtr: QElemPtr; theSlot: Integer): OSErr;

System-Based Installation and Removal Routines

FUNCTION VInstall(vblTaskPtr: QElemPtr): OSErr;
FUNCTION VRemove(vblTaskPtr: QElemPtr): OSErr;

Utility Routines

FUNCTION AttachVBL(theSlot: Integer): OSErr;
FUNCTION DoVBLTask(theSlot: Integer): OSErr;
FUNCTION GetVBLQHdr: QHdrPtr;

Application-Defined Routine

PROCEDURE MyVBLTask;

C Summary

Data Types

typedef pascal void (*VBLProcPtr)(void);
typedef struct {              /*VBL queue element*/
      QElemPtr    qLink;      /*next entry in vertical retrace queue*/
      short       qType;      /*queue type*/
      VBLProcPtr  vblAddr;    /*pointer to task procedure*/
      short       vblCount;   /*interrupts until next execution*/
      short       vblPhase;   /*task phase*/
} VBLTask;

Vertical Retrace Manager Routines

Slot-Based Installation and Removal Routines

pascal OSErr SlotVInstall(QElemPtr vblTaskPtr, short theSlot);
pascal OSErr SlotVRemove(QElemPtr vblTaskPtr, short theSlot);

System-Based Installation and Removal Routines

pascal OSErr VInstall(QElemPtr vblTaskPtr);
pascal OSErr VRemove(QElemPtr vblTaskPtr);

Utility Routines

pascal OSErr AttachVBL(short theSlot);
pascal OSErr DoVBLTask(short theSlot);
#define GetVBLQHdr()((QHdrPtr) 0x0160)

Application-Defined Routine

pascal void MyVBLTask(void);

Assembly-Language Summary

Constants

vType             EQU      1        ;VBL queue element type
inVBL             EQU      6        ;bit index for VBL active flag

Data Structures

VBL Queue Element

0	vblink	long	next entry in vertical retrace queue
4	vblType	word	queue type
6	vblAddr	long	address of task procedure
10	vblCount	word	interrupts until next execution
12	vblPhase	word	phase count

Global Variables

CrsrBusy	byte	Set to TRUE if the cursor is being changed.
jDoVBLTask	long	Jump vector for DoVBLTask routine.
ScrnVBLPtr	long	Pointer to the primary monitor's vertical retrace queue's header.
VBLQueue	10 bytes	Header of the vertical retrace queue.

Result Codes

noErr	0	No error
qErr	-1	Task entry isn't in the queue
vTypErr	-2	Invalid qType value (must be ORD(vType))
slotNumErr	-360	Invalid slot number