From: William James <w_a_x_man@...>
Date: 2007-09-22T16:25:03+09:00
Subject: Re: I am new to Ruby and I could use some expert advice as to how I can make this code run faster.


Ruby Maniac wrote:
> I am new to Ruby and I could use some expert advice as to how I can
> make this code run faster.
>
> def scramble(fname)
>     f = File.new(fname, "rb")
>     _fname = fname + ".scrambled"
>     begin
>         File.exist?(_fname) if File.delete(_fname)
>     rescue
>     end
>     ff = File.new(_fname, "wb+")
>     for l in f
>         l.each_byte{|c| ff.write((c | 0x80).chr) }
>     end
>     f.close()
>     ff.close()
> end

About 2.8 times as fast.

def scramble( fname )
  _fname = fname + ".scrambled"
  mask = 0x8080808080808080
  data = File.open( fname, "rb" ){|f| f.read }
  pad = (8 - (data.size % 8)) % 8
  data << "p" * pad
  File.open( _fname, "wb"){|ff|
    array = data.unpack('Q*')
    array.map!{|x| x | mask }
    ff.write( array.pack('Q*')[0 ... -pad] )
  }
end