write_table - write design as connectivity table

    write_table [options] [filename]

Write the current design as connectivity table. The output is a tab-separated
ASCII table with the following columns:

  module name
  cell name
  cell type
  cell port
  direction
  signal

module inputs and outputs are output using cell type and port '-' and with
'pi' (primary input) or 'po' (primary output) or 'pio' as direction.