// James Davis - jedavis@cs.stanford.edu - Copyright 1996

// Routines to make application access to deferred task manager easier

#include "DeferredTask.h"

typedef struct {
	DeferredTask theDTTask;
	long	theA5World;
	DeferredTaskUPP theRealTask;
} DTInfo, *DTInfoPtr;


// Preallocate some space for the DeferredTask structures. Since we cant ask for
// memory at interupt time we do it now in advance. Get as much as we might need.
// We just get an array of the max tasks that might be active
DTInfo DT_TaskInfoArray[DT_MAX_DEFERRED_TASKS];
long DT_TaskInfoCount=0; // the next taskrec to use

// Get our deferred task parameter out of A1 and put it where its useful
asm DTInfoPtr DT_GetTaskParm(void);
asm DTInfoPtr DT_GetTaskParm(void)
{
move.l A1,A0  // The dtParm field is pointed to by A1 when the routine is first called
              // Pointers are returned in A0 so move it there...
rts
}

// We need a stub task to reset the A5 world to our application and then call our
// real task.
pascal void DT_StubTask(void);
pascal void DT_StubTask(void)
{
DTInfoPtr dtinfo;
long oldA5;

dtinfo = DT_GetTaskParm();  // get the param out of A1
oldA5 = SetA5(dtinfo->theA5World);  // Restore the application A5

if (dtinfo->theRealTask != NULL)
	dtinfo->theRealTask();  // Call the task the user really wanted

oldA5 = SetA5(oldA5);  // reset the calling A5

}

// Install a deferredtask, should only be called from interupt code.
// assumes a valid aaplication a5 world on entry
void DT_InstallDeferredTask(DeferredTaskUPP deferredTask)
{
DTInfoPtr dtinfo;

// find the current taskrecord to use
dtinfo= &DT_TaskInfoArray[DT_TaskInfoCount];
DT_TaskInfoCount = (DT_TaskInfoCount+1)%DT_MAX_DEFERRED_TASKS;

dtinfo->theDTTask.qType=dtQType;  // deferred task type
dtinfo->theDTTask.dtAddr=DT_StubTask;  // call our stub which sub calls the intended routine
dtinfo->theDTTask.dtParam=(long)dtinfo; // our parameter to retrieve
dtinfo->theDTTask.dtReserved=0;  // just set it to 0, dont ask questions
dtinfo->theA5World=SetCurrentA5(); // save the current a5
SetA5(dtinfo->theA5World); // restore the A5 we just blitzed 
dtinfo->theRealTask=deferredTask;  // point to the task we want to run

// install the routine in the deferred task queue
DTInstall(&(dtinfo->theDTTask));
}