Re: [Boost-bugs] [Boost C++ Libraries] #9235: Construction from binary data

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #9235: Construction from binary data
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2013-10-12 16:27:01

#9235: Construction from binary data
-------------------------------+----------------------------
  Reporter:  psiha             |      Owner:  johnmaddock
      Type:  Feature Requests  |     Status:  reopened
 Milestone:  To Be Determined  |  Component:  multiprecision
   Version:  Boost 1.54.0      |   Severity:  Optimization
Resolution:                    |   Keywords:
-------------------------------+----------------------------
Changes (by johnmaddock):

 * type:  Bugs => Feature Requests

Comment:

 It's not quite as trivial as you think: the internal data layout is highly
 platform/compiler dependent.  For example a 128-bit integer is represented
 as 4 32 bit words on MSVC, but as a single 128-bit value on GCC-x64 (which
 has {{{__int128}}}).

 Re (1), conversion from a hex string is fast, but decimal string
 conversion is heavyweight: of course they use the same routine though.
 Your example(4) is solved by user-defined literals I believe - it's the
 optimally efficient solution as it's all done at compile-time.  For (3)
 would get_byte/set_byte non-member functions (similar to the existing bit
 twiddling functions) do the job?  Note that these would only be efficient
 for unsigned types: signed types would require a check for negative values
 and the associated error handling - and yes that means exceptions.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/9235#comment:5>
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