From: Robert Klemme <shortcutter@...>
Date: 2008-06-14T21:59:20+09:00
Subject: Re: Binary string packing/unpacking issues

On 14.06.2008 13:56, Lucas L. wrote:
> Dave Bass wrote:
>> "Pixels".each_byte { |b| printf("%08b\n", b) }
> 
> That's good for the first problem, thanks.
> Now for the more difficult one of efficiently manipulating small 
> portions of the packed binary data.

With Ruby 1.8 you can easily manipulate individual bytes directly:

irb(main):006:0> s="abc"
=> "abc"
irb(main):007:0> s[2]
=> 99
irb(main):008:0> s[2].to_s 2
=> "1100011"
irb(main):009:0> s[2] |= 4
=> 103
irb(main):010:0> s
=> "abg"
irb(main):011:0> s[2].to_s 2
=> "1100111"

I don't have a 1.9 handy so I can't tell you how to do it there.  But 
the basic lesson should be, that you can leave your data in a String and 
manipulate it directly there.

Kind regards

	robert