On Friday 16 March 2007 21:29, David Brown wrote:
Ian Lynagh wrote:
On Sun, Mar 11, 2007 at 08:18:44PM +0000, Dominic Steinitz wrote:
I have re-written the sha1 code so that it is (hopefully) easy to see
that it
faithfully implements the algorithm (see http://www.itl.nist.gov/fipspubs/fip180-1.htm). Having got rid of the
space
leak, I have been trying to improve performance.
Currently, the haskell code is 2 orders of magnitude slower than the
sha1sum
that ships with my linux.
I don't know if this is useful to you, but darcs has some SHA1 code that IIRC is much closer to C's performance. It currently uses darcs' own FastPackedString library, but porting it to ByteString should be fairly easy.
See SHA1.lhs in http://www.abridgegame.org/repos/darcs-unstable
It might even be able to be made faster still by calling lower-level functions than {shift,rotate}{L,R} directly.
I ended up deciding to call SHA1 routines out of openssl. For applications where this is possible, it does very well, I got about 2.5 times the speed out of it, compared to ordinary C implementations.
But, since harchive spends most of its CPU computing SHA1 hashes (and almost all of the rest in zlib), it is worth a complex binding there.
Dave Ian, Dave,
Thanks. My goal is to have natural haskell code that's reasonably efficient. I don't have a problem to solve that needs an efficient implementation of SHA1. I'm going to try apfelmus' suggestions next and then (if I ever get yhc to build) start looking at what gets generated. Dominic.