[Boost-bugs] [Boost C++ Libraries] #11590: cpp_int initialization inefficient

Subject: [Boost-bugs] [Boost C++ Libraries] #11590: cpp_int initialization inefficient
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2015-08-27 12:50:08

#11590: cpp_int initialization inefficient
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 Reporter:  Manfred Weis <manfredweis@…>  |      Owner:  johnmaddock
     Type:  Patches                       |     Status:  new
Milestone:  To Be Determined              |  Component:  multiprecision
  Version:  Boost 1.57.0                  |   Severity:  Optimization
 Keywords:                                |
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 I tried to create an cpp_int with about 10 million digits from a hex
 string "0x1....1"; it literally take ages.
 The reasons seems to be the repeated shift and add conversion from the
 characters; while that is inevitable for decimal digits, a hex encoded
 string would allow to directly determine the final position and shift in
 the corresponding limb.

 TODO: check supplied string for valid hex encoding, allocate enough zero-
 initialized limbs and then directly set the value of the corresponding
 limb.

 A further improvement would be to supply a conversion from a sequence of
 values that are stored in some linear container.

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Ticket URL: <https://svn.boost.org/trac/boost/ticket/11590>
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