/*
   =============================================================================
	mtinit.c -- Multi-Tasker -- initialization, etc.
	Version 31 -- 1988-04-15 -- 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		_MT_Swp();	/* swapper TRAP handler -- swap */
extern	short		_MT_Nxt();	/* swapper TRAP handler -- next */
extern	short		setipl();	/* set processor IPL function */

extern	TCB		*MT_TCBs;	/* TCB chain pointer */
extern	TCB		*MT_CurP;	/* current TCB pointer */
extern	TCB		*MT_RdyQ;	/* ready queue pointer */
extern	TCB		_MTptcb[2];	/* private TCBs */

extern	unsigned	MT_IDct;	/* next available task ID */

extern	unsigned	*_MT_Vc1;	/* old swapper TRAP vector 1 */
extern	unsigned	*_MT_Vc2;	/* old swapper TRAP vector 2 */

long			_MT_Stk[48];	/* a stack for _MT_Nil() */

TCB			_MT_TCB;	/* dummy TCB for shutdown */

/* 
*/

/*
   =============================================================================
	_MT_Nil() -- the NIL task  (must always be present on the ready queue)
   =============================================================================
*/

_MT_Nil()
{
	register short i, j;

	while (TRUE) {

		setipl(2);	/* make sure we're interruptable */

		for (i = 0; i < 10; i++)
			++j;

		DB_CMNT("_MT_Nil");
		MTSwap();
	}
}

/*
   =============================================================================
	MTInit() -- initialize the mutitasker and setup the task 0 default TCB
   =============================================================================
*/

MTInit()
{
	register short i, oldipl;
	register TCB *tcp;

	DB_ENTR("MTInit");
	oldipl = setipl(7);		/* DISABLE INTERRUPTS */

	MT_TCBs = &_MTptcb[1];		/* setup the TCB chain pointer */
	MT_RdyQ = &_MTptcb[0];		/* task 0 is on the ready queue */

	memsetw(&_MTptcb[0], 0, sizeof (TCB) / 2);	/* clear task 0 TCB */
	memsetw(&_MTptcb[1], 0, sizeof (TCB) / 2);	/* clear task 1 TCB */

	_MTptcb[0].flags    = MTF_OCC | MTF_RDY;	/* set task 0 ready ... */
	_MTptcb[0].slice    = -1L;			/* ... not time-sliced */
	_MTptcb[0].pc       = _MT_Nil;			/* ... NIL task */
	_MTptcb[0].sp       = &_MT_Stk[48];		/* ... set stack space */
	_MTptcb[0].reg[15]  = &_MT_Stk[48];		/* ... and a7 */
	_MTptcb[0].sr       = MT_NilSR;			/* ... set sr */

	MT_CurP = &_MTptcb[1];		/* task 1 is the current task */

	_MTptcb[1].fwd   = &_MTptcb[0];		/* point at next TCB */
	_MTptcb[1].flags = MTF_OCC | MTF_RUN;	/* set task 1 running ... */
	_MTptcb[1].pri   = MT_DfPri;		/* ... default priority */
	_MTptcb[1].slice = -1L;			/* ... not time-sliced */
	_MTptcb[1].tid   = 1;			/* ... set task ID */

	MT_IDct = 2;			/* next task ID = 2 */

	_MT_Vc1 = BIOS(B_SETV, 40, _MT_Swp);	/* set swapper TRAP vector 1 */
	_MT_Vc2 = BIOS(B_SETV, 41, _MT_Nxt);	/* set swapper TRAP vector 2 */

	setipl(oldipl);			/* RESTORE INTERRUPTS */
	DB_EXIT("MTInit");
}