Isn't a circular array implemented with a modula to begin with? I don’t see how you bypass it

  m3=m5=m7=1
  for ...
    ...
    m3 = m3==2?0:m3+1
    m5 = m5==4?0:m5+1
    m7 = m7==6?0:m7+1

You keep two counters.