/*
   =============================================================================
	mtrun.c -- Multi-Tasker -- task initialization, etc.
	Version 8 -- 1988-04-12 -- D.N. Lynx Crowe
	(c) Copyright 1988 -- D.N. Lynx Crowe
   =============================================================================
*/

#include "stddefs.h"
#include "biosdefs.h"
#include "mtdefs.h"
#include "debug.h"

extern	short		setipl();	/* set processor IPL function */
extern	short		MTExit();	/* task termination function */

extern	struct _mt_def	*_MT_;		/* Multi-Tasker structure pointer */

/* 
*/

/*
   =============================================================================
	MTRun() -- initialize and start a task

		SUCCESS		TCB created and placed on ready queue
		FAILURE		no TCB available for task
   =============================================================================
*/

short
MTRun(tid, pri, stat, slice, pstack, func, par)
unsigned tid;
register unsigned pri;
unsigned stat;
long slice, pstack;
short (*func)();
long par;
{
	register short oldipl;
	register TCB *rcur, *rprv, *tcp;

	DB_ENTR("MTRun");

	if ((struct _mt_def *)NIL EQ _MT_)
		_MT_ = (struct _mt_def *)XBIOS(X_MTDEFS);

	tcp = _MT_->mtp->TCBs;			/* point at the first TCB */
	oldipl = setipl(7);			/* DISABLE INTERRUPTS */

	while (tcp) {				/* search for a free TCB */

		if (NOT (tcp->flags & MTF_OCC)) {

			/* setup the TCB */

			tcp->tos = pstack;		/* put top of stack in TCB */

			pstack -= 4L;			/* adjust stack pointer */
			*(long *)pstack = par;		/* store task parameter */

			pstack -= 4L;			/* adjust stack pointer */
			*(long *)pstack = MTExit;	/* store return address */

			tcp->flags    = MTF_OCC;	/* flags = TCB occupied */
			tcp->tid      = tid;		/* ID */
			tcp->pri      = pri;		/* priority */
			tcp->slice    = slice;		/* time slice */
			tcp->sp       = pstack;		/* stack pointer */
			tcp->reg[15]  = pstack;		/* a7 */
			tcp->pc       = func;		/* program counter */
			tcp->sr       = stat;		/* status register */
/* 
*/
			rcur = (TCB *)&_MT_->mtp->RdyQ;	/* point at the head of the queue */

			while (TRUE) {

				rprv = rcur;		/* previous TCB = current TCB */
				rcur = rprv->next;	/* current TCB = next TCB */

				if (rcur EQ (TCB *)NIL)	/* enqueue here if next was NIL */
					break;

				if (pri > rcur->pri)	/* enqueue here if priority is greater */
					break;
			}

			rprv->next  = tcp;		/* set next of previous TCB to new TCB */
			tcp->next   = rcur;		/* set next of new TCB to old next */
			tcp->flags |= MTF_RDY;		/* set the ready flag in the new TCB */

			setipl(oldipl);		/* RESTORE INTERUPTS */
			DB_EXIT("MTRun - SUCCESS");
			return(SUCCESS);	/* return -- SUCCESS */
		}

		tcp = tcp->fwd;			/* look at next TCB */
	}

	setipl(oldipl);				/* RESTORE INTERRUPTS */
	DB_EXIT("MTRun - FAILURE");
	return(FAILURE);			/* return -- FAILURE */
}