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Re: [PATCH] Add a birdview-on-the-source-code section to the user manual

From
Johannes Schindelin <johannes.schindelin@gmx.de>
Date
May 9, 2007, 16:25 UTC
Message-ID
<Pine.LNX.4.64.0705091822590.4167@racer.site>
In-Reply-To
<Pine.LNX.4.64.0705091210570.18541@iabervon.org>
Hi,
On Wed, 9 May 2007, Daniel Barkalow wrote:
Show 20 quoted lines
> On Wed, 9 May 2007, Johannes Schindelin wrote:
> 
> > > To be honest, I wouldn't even be *thinking* about the endianity of SHA-1
> > > octet representation (you don't usually really deal with the hash as
> > > with a number, so expecting to have it in native endianity is not very
> > > natural; you just deal with it as with a data blob) and the
> > > "(big-endian)" would only confuse me and get me thinking about "huh, do
> > > they swap the bytes, or wait, they don't, ...?!".
> > > 
> > > But that's maybe just me.
> > 
> > But then, maybe it is just me? I got it completely wrong the first time, 
> > fully expecting the calculations to be carried out in host endianness for 
> > performance reasons.
> 
> I think the Mozilla implementation carries out calculations in host 
> endianness, and transfers data from the input to the internal state and 
> >from the internal state to the final hash with shifts and masks.
> 
> Which calculations are you seeing that involve byte order?

None. I only suspected them to be carried out in byte order. From what I know, there are some shifts involved, which might or might not be helped by 32-bit arithmetic.

I did not really look into it.
>From my prior debugging experiences on Intel, though, I automatically 

looked for the least significant bytes at the beginning of those "sha1" variables, and came up empty.

Ciao, Dscho

Previous: Daniel BarkalowNext: J. Bruce Fields
Message 22 of 33 in “Add a birdview-on-the-source-code section to the user manual”
  1. Add a birdview-on-the-source-code section to the user manualJohannes Schindelin, May 8, 2007
  2. Karl HasselströmMay 8, 2007
  3. Johannes SchindelinMay 8, 2007
  4. Karl HasselströmMay 8, 2007
  5. Johannes SchindelinMay 8, 2007
  6. Karl HasselströmMay 8, 2007
  7. Daniel BarkalowMay 9, 2007
  8. Karl HasselströmMay 9, 2007
  9. Johannes SchindelinMay 9, 2007
  10. Karl HasselströmMay 9, 2007
  11. J. Bruce FieldsMay 9, 2007
  12. Junio C HamanoMay 9, 2007
  13. Junio C HamanoMay 9, 2007
  14. Johannes SchindelinMay 9, 2007
  15. J. Bruce FieldsMay 9, 2007
  16. Karl HasselströmMay 9, 2007
  17. Johannes SchindelinMay 9, 2007
  18. Johannes SchindelinMay 9, 2007
  19. Petr BaudisMay 9, 2007
  20. Johannes SchindelinMay 9, 2007
  21. Daniel BarkalowMay 9, 2007
  22. Johannes SchindelinMay 9, 2007
  23. J. Bruce FieldsMay 9, 2007
  24. Johannes SchindelinMay 9, 2007
  25. J. Bruce FieldsMay 9, 2007
  26. Daniel BarkalowMay 9, 2007
  27. Johannes SchindelinMay 9, 2007
  28. Karl HasselströmMay 10, 2007
  29. J. Bruce FieldsMay 9, 2007
  30. Junio C HamanoMay 10, 2007
  31. Add a birdview-on-the-source-code section to the user manualJohannes Schindelin, May 10, 2007
  32. Junio C HamanoMay 10, 2007
  33. Karl HasselströmMay 10, 2007

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