Re: Bit manipulation

["Ken Garlington" <Ken.Garlington@computer.org>]

As I recall, there was also an implied desire to avoid a loop. How about:

package Word_Bitstring is
  type Object is array (1 .. 32) of Boolean;
  pragma Pack(Object);

  function Swap (O : Object) return Object;
end Word_Bitstring;

package body Word_Bitstring is
  function Swap (O : Object) return Object is
  begin
    return O(32) & O(31) & O(30) & O(29) &
           O(28) & O(27) & O(26) & O(25) &
           O(24) & O(23) & O(22) & O(21) &
           O(20) & O(19) & O(18) & O(17) &
           O(16) & O(15) & O(14) & O(13) &
           O(12) & O(11) & O(10) & O(09) &
           O(08) & O(07) & O(06) & O(05) &
           O(04) & O(03) & O(02) & O(01);
  end Swap;
end Word_Bitstring;

Seems a little error prone, but it might be reasonably efficient. Try it and
see!

"Redryder" <john.f.anderson@mindspring.com> wrote in message
news:3A0DF35D.729DDE15@mindspring.com...
: Jeff,
:  It goes like this: BIT 0 to BIT 31, BIT 31 to BIT 0 ,  and so on.
: John
:
: Jeff Carter wrote:
:
: > Redryder wrote:
: > >
: > > I need to swap the bits in a 32-bit word.
: >
: > I could perhaps be of more assistance if I knew what you mean by "swap
: > the bits".
: >
: > --
: > Jeff Carter
: > "I unclog my nose towards you."
: > Monty Python & the Holy Grail
: