pattern=klass()
function pattern:init(p)
 self.pflags=pflags:new(p)

 self.nflags={}
 for i=0,31 do  -- because the user could change the length
  self.nflags[i]=nflags:new{}
 end
end
function pattern:plot(ix, n)
 assert_range(ix,0,self.pflags.len,"ix")
 self.nflags[ix]=nflags:new(n)
end
function pattern:silent()
 for i=0,31 do
  if (self.nflags[i].v!=0) return
 end
 return true
end
function pattern:key()
 local key=0
 for i=0,self.pflags.len-1 do
  key ^= self.nflags[i]:encode()>>(i%16)
 end
 return key
end
function pattern:eq(other)
 if (self.pflags:encode() != other.pflags:encode()) return

 for i=0,self.pflags.len-1 do
  if (self.nflags[i]:encode()!= other.nflags[i]:encode()) return
 end
 return true
end
function pattern:map_to(ix)
 self.map_ix=ix

 local at=0x3200+ix*68
 poke4(at+64,self.pflags:encode())

 for i=0,31 do
  poke2(at+i*2,self.nflags[i]:encode())
 end
end