; decimation in time - reorder data
; pre-transform bit swap
; uses lookup table for speed
;
permute:
	mov	dph,#high pert
	mov	p2,#high real
	mov	r1,#low real		; 'L'
perm2:	mov	dpl,r1
	movx	a,@dptr
	cjne	a,dpl,brv2		; cmp with E
brv2:	jc	swp1
	mov	r0,a
	movx	a,@r1
	mov	r2,a
	movx	a,@r0
	movx	@r1,a
	mov	a,r2
	movx	@r0,a
swp1:	inc	r1			; inc 'L'
	mov	a,r1
	jnz	perm2