Author: Dann Corbit
Date: 15:22:10 04/09/02
Go up one level in this thread
On April 09, 2002 at 17:32:15, Alvaro Jose Povoa Cardoso wrote:
>Does anyone kow how to do a fast 32bit bitboard mirroring?
>bit 0 -> bit 31
>bit 1 -> bit 30
>bit 2 -> bit 29
>...etc
>
>I would like to do it fast.
>
>Best regards,
>Alvaro Cardoso
Another simple technique is:
1. Swap 2 byte unsigned ints (unsavory union hack) {non-portable, allowed to
cause nasal demons to fly out of your nose but works most of the time anyway}
2. Swap unsigned chars within those ints (same)
3. Swap bits within the bytes by table lookup of 256 entries.
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