3 ms·

Actually, barrel shifters are not that small. Added are significantly cheaper in terms of chip area.

• tempguy9999 7y ago
  Seriously?? It's the same bit pattern, err, shifted. Adders have got to carry, at each stage (ripple carry?). I am amazed, thanks.
  • Robin_Message 7y ago
    Think of it this way: a barrel shifter has to be able to "carry" every bit to (potentially) every other bit.
    • tempguy9999 7y ago
      Yep, but also while aligned. Bits x and y are going to be the same distance apart, always, unless shifted off the end (where they can wrap or be lost). Thinking of this in the pub it seemed a butterfly thingy would be appropriate <https://en.wikipedia.org/wiki/Butterfly_network> https://en.wikipedia.org/wiki/Butterfly_network>. Further thinking suggested there'd be a ton of wires doing this, and perhaps it's the wiring that's taking up the silicon?
      • namibj 7y ago
        It's the multiplexers. Also, critical path is going towards limiting your speed: https://en.wikipedia.org/wiki/Barrel_shifter https://en.wikipedia.org/wiki/Barrel_shifter
  • deleted 7y ago
    [deleted]