{ signal: [
  {    name: 'clk',   wave: 'p..Pp..P'},
  ['Master',
    ['ctrl',
      {name: 'write', wave: '01.0....'},
      {name: 'read',  wave: '0...1..0'}
    ],
    {  name: 'addr',  wave: 'x3.x4..x', data: 'A1 A2'},
    {  name: 'wdata', wave: 'x3.x....', data: 'D1'   },
  ],
  {},
  ['Slave',
    ['ctrl',
      {name: 'ack',   wave: 'x01x0.1x'},
    ],
    {  name: 'rdata', wave: 'x.....4x', data: 'Q2'},
  ]
]}