;pass1
	ldx sort+0
	ldy spry,x        ; get sprite y coord
	lax and#0fmul16,y ;get bucket startadress 
	ora bucket1+15,x  ;get adress INside the bucket
	inc bucket1+15,x  ;inc nr of elements
	tax		
smod	sty bucket1,x	  ;store spr to bucket



;pass2

	ldx bucket1+15
	beq next	;empty bucket dont bother
blp1	

	ldy bucket1,x
	lda spry,y         ;get spr y
	and #%11110000     ;upper 4 bits only this time
	tay                ;which is exactly our pointer
	ora bucket2+15,y   ;addy inside bucket
	inc bucket2+15,y   ;inc bucket counter
	tay                ;final bucket addy
	sta bucket2,y      ;store sprite
	dex
	bne blp1	   ;any more in bucket1?

next

;pass3
        ldy #$00 ; nr of sprites counter this is done only once

	ldx bucket2+15
	beq next             ;empty bucket?
blp2
	lda bucket2,x        ;get sprite nr
smod	sta final,y          ;store to final list
	iny                  ;final spr count
	dex           
	bne blp2             ;any more in curr. bucket?

	;; initialize the buckets
	ldx #$81
	!for i,0,16 {
	sta lsd_bucket+i
	}
	lda #$fe
	!for i,0,6 {
	sax msd_bucket+i*2+0
	stx msd_bucket+i*2+1
	sbx #-3
	}

	;; lsd sort
	lda #$0f
	!for i,0,32 {
	ldx actor_ypos+i
	sbx #$00
	ldy lsd_bucket,x
	sty actor_link+i
	ldy #i
	sty lsd_bucket,x
	}

	;; msd sort
	!for i,0,13 {
	ldx lsd_bucket+i
	bmi .next

.msd	ldy actor_ypos,x
	lda msd_table,y
	tay

	lda msd_bucket,y
	stx msd_bucket,y

	ldy actor_link,x
	sta actor_link,x
	bmi .next

	ldx actor_ypos,y
	lda msd_table,x
	tax

	lda msd_bucket,x
	sty msd_bucket,x

	ldx actor_link,y
	sta actor_link,y
	bne .msd

.next	}

	;; finally in the mux writer.
	;; for each sprite, alternating x and y
	ldx actor_link,y
	bpl .ok
.bucket	lda msd_bucket-$80,x
	tax
	bmi .bucket
.ok	...