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Inside Macintosh: Devices /

Chapter 2 - Slot Manager / Slot Manager Reference

Data Structures

Slot Interrupt Queue Element

The Slot Manager maintains a queue of interrupt handlers for each slot. You use the SIntInstall and SIntRemove functions (described on page 2-70 and page 2-71, respectively) to install and remove routines in the queue. The SlotIntQElement data type defines a slot interrupt queue element.

TYPE SlotIntQElement =           {slot interrupt queue element}
RECORD
   sqLink:        Ptr;           {pointer to next queue element}
   sqType:        Integer;       {queue type ID; must be sIQType}
   sqPrio:        Integer;       {priority value in low byte}
   sqAddr:        ProcPtr;       {interrupt handler}
   sqParm:        LongInt;       {optional A1 parameter}
END;

Field Description

sqLink

A pointer to the next queue element. This field is maintained by the Slot Manager.

sqType

The queue type identifier, which you set to the defined type sIQType.

sqPrio

The relative priority level of the interrupt handler. Only the low-order byte of this field is used. The high-order byte must be set to 0. Valid priority levels are 0 through 199. Priority levels 200 through 255 are reserved for Apple devices.

sqAddr

A pointer to the interrupt handler.

sqParm

An optional value that the Slot Manager places in register A1 before calling the interrupt handler. This field is typically used to store a handle to a driver's device control entry.