From: Pito Salas <rps@...>
Date: 2009-07-17T04:20:04+09:00
Subject: Re: Help with making this prettier?

Chris Howe wrote:
> How about this:
> 
> def bit_field(from,to,val)
>  return ( val>>from ) & ( (2 << (to - from) ) - 1)
> end
> In binary 2<<(to-from) is going to be a 1 with (to-from+1) zeros after 
> it,
> subtracting 1 leaves you with just (to-from+1) 1's in the lower bits of 
> the
> number.
> 
> val>>from shifts the bit field over to the lower bits.
> 
> Bitwise anding the two together masks off the upper order bits of val,
> leaving you with the value you are looking for.

Thanks. Beautiful, and nice explanation too!

- Pito

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