create EIA 608 byte pairs

create.cr

to_encode = "abcdABCD"
outy = Array(UInt8).new
to_encode.each_char{|c|
  if c.in_set?("A-Z")
    outy << 0x41_u8 + (c - 'A') # https://en.wikipedia.org/wiki/EIA-608#Characters
  elsif c.in_set?("a-z")
    outy << 0x61_u8 + (c - 'a')
  else
    raise "don't translate more chars yet"
  end
}

# add parity bit
outy.map!{|c|
  parity = true;
  (0..7).each{|bit_count|
    if c.bit(bit_count) == 1
      parity = !parity
    end
  }
  if parity
    c = c | 0b10000000; # add parity bit
  end
  c
}

outy.each{|c| puts "%08b" % c }
File.open(ARGV[0], "w") { |f|
  outy.each{|c| # punt!
    f.write_byte c
  }
}
puts "wrote to #{ARGV[0]}"