[Don_Adan]

Originally Posted by mcgeezer

OK, so for some odd reason I can't get the movem.w to work... I get wrong values coming in from the lookup table, at first I thought it could be the upper word of d2/d3/d4/d5 not being zero but I recall these are set anyway when a word operand is used.

	move.l	d4,a2
	move.l	d5,a3
	
.copy_tile_right:				; Right copy
	movem.w	(a0)+,d2/d3/d4/d5
	move.w	(a5,d2.l*2),(a1)		; Bitplane 1
	move.w	(a5,d3.l*2),8(a1)		; Bitplane 2
	move.w	(a5,d4.l*2),128*16(a1)		; Bitplane 3
	move.w	(a5,d5.l*2),(128*16)+8(a1)	; Bitplane 4
	add.l	d0,a1
	dbf	d1,.copy_tile_right

	move.l	a2,d4
	move.l	a3,d5

It makes no difference anyway because this code is slower than this:

.copy_tile_right:				; Right copy
	move.w	(a0)+,d2
	beq.s	.1b
	move.w	(a5,d2.l*2),(a1)		; Bitplane 1
	
.1b:	move.w	(a0)+,d2
	beq.s	.2b
	move.w	(a5,d2.l*2),8(a1)		; Bitplane 2
	
.2b:	move.w	(a0)+,d2
	beq.s	.3b
	move.w	(a5,d2.l*2),128*16(a1)		; Bitplane 3
	
.3b:	move.w	(a0)+,d2
	beq.s	.4b
	move.w	(a5,d2.l*2),(128*16)+8(a1)	; Bitplane 4
	
.4b:	add.l	d0,a1
	dbf	d1,.copy_tile_right

Thank you everyone for their input, it was really interesting!

Graeme

I think that if you want to reach maximum speed, you can use two versions. First for flip images with many null words values, and second for flip images with small numbers of null words. Two short routines and one 128KB table. For access to table for movem.w you must set A5 as A5 + 64K, because negative longword values (auto extending). Anyway D2.W*2 is enough.