mov r17,r16 ;Swap odd and even 1-bit fields
andi r16,$55
lsl r16
andi r17,$AA
lsr r17
or r16,r17
mov r17,r16 ;Swap odd and even 2-bit fields
andi r16,$33
lsl r16
lsl r16
andi r17,$CC
lsr r17
lsr r17
or r16,r17
swap r16 ;Swap odd and even 4-bit fields
ret