Subject: [boost] Multiprecision vs. xint
From: Phil Endecott (spam_from_boost_dev_at_[hidden])
Date: 2012-06-15 07:27:13
I'd like to encourage people who are looking at the proposed
Multiprecision library to remind themselves of the xint review last
year. See e.g.
http://thread.gmane.org/gmane.comp.lib.boost.devel/215968 (my review)
To what extent do we believe that this new library addresses the
weaknesses of the last proposal?
It would be great if Vladimir Prus, review manager for xint, could
write a review of Multiprecision.
Here's my take on it:
Multiprecision addresses many of the problems of xint, and also extends
the scope into areas that xint did not address at all. However it
still suffers some of the same problems: if I want an int128_t that is
just 128 bits of data, it doesn't help me. Furthermore, it doesn't
help me to build the int128_t that I want. Although Multiprecision is
divided into "front" and "back"-ends, this division is not in the right
place to let me substitute my own backend that just provides the 128
bits of storage. In the xint reviews, we suggested that the algorithms
should be decoupled from the data structures and the same applies
here. Similarly, this implementation doesn't provide hooks that would
allow me to substitute e.g. assembler implementations of the algorithms.
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