From: Sebastian Hungerecker <sepp2k@...>
Date: 2010-05-17T07:12:44+09:00
Subject: Re: Array conversion

On 16.05.2010 23:58, Paul A. wrote:
> I have a array of 32 bits digests such as this one:
>
>    array = [1717922406, 543519338, 543585641, 1701343776, 1718969704,
> 544368245, 1751457906, 1713399157]
>
> And I would like to convert it into another array of 128 bits digests.
>
> According so test, I think the such array is:
> [136107835579490162288229994478942319136,
> 136190811075650685875822190301307495797]
>
> Do you know if there is a simple way to do a such array conversion.
>    

Group the array into slices of 4 and then "concatenate" each slice
by shifting and adding:

array.each_slice(4).map do |slice|
   slice.inject(0) do |sum,ele|
     (sum<<32) + ele
   end
end
#=> [136107835579490162288229994478942319136, 
136190811075650685875822190301307495797]