Bugs or features?
tg at swox.com
Sat Feb 16 01:19:57 CET 2008
I am just wondering if this is by design or if this is a bug?
The question if this is the intended functionality of the >>= operator
for negative numbers. This differs from how it is defined for native
types like int for example.
This is a sticky issue.
In the C standard, the behaviour of right shift of negative numbers is
undefined. But in practice, almost every compiler defines it as
rounding towards -oo. The one exception I am aware of is Cray's
compilers for their vector systems. (They shift the numbers logically
always, which is not very helpful.)
I am inclined to changing gmpxx.h to make it follow the common
behaviour, although that is not formally standardized.
What do people think? I am mainly interested in the opinion of people
that actually use gmpxx.h.
(The change is trivial, just change the t to an f in mpz_tdiv_q_2exp
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