** With this file I supply 68030 fixpoint calculation. To use this
** instead of the normal 68000 function, assemble it via
** 		asm -m2 fixpoint030
** You then should set the 68030 option with the Options program
** and click on the "build" icon.
** The function is short enough to fit completely into the 68030
** program cache and should be *REALLY* fast.

	CSECT	DATA,1,,2,2

	XREF	_maxcol
	XREF	_MAXITER

	CSECT	TEXT,0,,1,2

	XDEF	_Iter_FXP

_Iter_FXP:
	movem.l	D3-D7,-(SP)		;save registers
	move.l	D1,D3			;p = r
	move.l	D2,D4			;q = i
	move.w	_MAXITER(A4),D0
	ext.l	D0

__while:
	move.l	D1,D6			;calc. rČ
	muls.l	D1,D5:D6
	asl.l	#8,D5			;normalize
	rol.l	#8,D6
	move.b	D6,D5

	move.l	D2,D7			;calc. iČ
	muls.l	D2,D6:D7
	asl.l	#8,D6			;normalize
	rol.l	#8,D7
	move.b	D7,D6

	add.l	D6,D5

;now D5 contains rČ+iČ

	cmp.l	A2,D5			;test for upper bound
	bge	__done			;exceeded => end

	move.l	D1,D5			;calc. x+i
	add.l	D2,D5

	move.l	D1,D6			;calc. x-i
	sub.l	D2,D6

	muls.l	D5,D5:D6		;calc. (x+i)*(x-i)
	asl.l	#8,D5			;normalize
	rol.l	#8,D6
	move.b	D6,D5

	add.l	D3,D5			;add p

;D5 now contains (x+i)(x-i)+p

	muls.l	D1,D6:D2		;calc. 2xi+q
	asl.l	#8,D6			;normalize
	rol.l	#8,D2
	move.b	D2,D6
	add.l	D6,D6			;*2
	add.l	D4,D6			;add q

;D6 now contains 2xi+q

	move.l	D5,D1			;r = (x+i)(x-i)+p
	move.l	D6,D2			;i = 2xi+q

	dbra	D0,__while		;to start of loop

	moveq	#0,D0			;return 0, if MAXITER was exceeded
	movem.l	(SP)+,D3-D7
	rts

__done:
	divu.w	_maxcol(A4),D0		;return ( count % maxcol )
	clr.w	D0
	swap	D0

	movem.l	(SP)+,D3-D7
	rts

	END