From: Brian Candler <b.candler@...>
Date: 2010-03-22T18:31:01+09:00
Subject: Re: Decompressing LZW compression from PDF file

> Example of working LZW decompression in python is here:
> http://pastebin.ca/1849009
> My translated code in ruby is here: http://pastebin.ca/1849012

Which version of ruby are you using? If it's 1.9 then your @fp[@inc] may 
fall foul of the character encoding rules. Try this in your initialize:

    puts @fp.encoding
    @fp.force_encoding("ASCII-8BIT")

However if you pass in a StringIO rather than a String then you can just 
copy what python is doing:

    x = @fp.read(1)
    @buff = x[0].unpack("C").first

and read(1) always reads single bytes. This has the advantage of being 
able to decompress directly from files, without reading them into RAM 
first.

Minor suggestion: it might be more rubyish to return nil rather than 
raise EOFError, which would simplify your run loop to

    result = ""
    while code = readbits(@nbits)
        result << feed(code)
    end
    return result

Regards,

Brian.
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