phc-discussions - RE: [PHC] Combining sliding window and bit-reversal

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Message-ID: <012301cf1bbe$43bc16d0$cb344470$@cfl.rr.com>
Date: Mon, 27 Jan 2014 19:17:00 -0500
From: "Gary W. Hvizdak" <gary.hvizdak@....rr.com>
To: <discussions@...sword-hashing.net>
Subject: RE: [PHC] Combining sliding window and bit-reversal

Bill Cox wrote ...

The Catena code does it this way:

- swap 4 bytes little-endian to big-endian style - 4 cycles max, or 1
in parallel.
- swap each upper nibble with the lower nibble:
    x = ((x & F0F0F0F0) >> 4) | ((x & 0x0F0F0F0F) << 4)
- swap bit pairs...

--

This looks like it's reversing at the byte level.  I had assumed the
objective was to reverse the entire 64 bits?

Gary