From: Paul Brannan <pbrannan@...>
Date: 2001-10-05T01:14:52+09:00
Subject: [ruby-talk:22092] Re: Help with Array#pack

On Fri, 5 Oct 2001, Jason Voegele wrote:

> command = [1, 0, 1|2, 0x1000, 99, 0]
>
> These six entries in the array should correspond to the six fields in
> the message header above.  So the above array should be converted to
> the binary string:
>
> BYTE 1 | BYTE 2 | BYTES 3&4 | BYTES 5-8 | BYTES 9-12 | BYTES 13-16
> ------ | ------ | --------- | --------- | ---------- | -----------
>    1   |   0    |    3      |    4096   |     99     |     0

Try this:

  def pack(arr)
    arr.pack("CCnnnn")
  end

  def display(x)
    x.each_byte do |b|
      puts b
    end
  end

  x = pack([1, 0, 1|2, 0x1000, 99, 0])
  display x

The 'C' means unsigned char, and the 'n' means 16-bit short (in
network-byte-order, which is very important).

Paul