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From: Robert Dewar <robert_dewar@my-deja.com>
Newsgroups: comp.lang.ada
Subject: Re: bitstreams
Date: Tue, 16 Jan 2001 00:59:12 GMT
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In article <93vik8$u08$1@nnrp1.deja.com>,
  mark_lundquist@my-deja.com wrote:
> Note that shift and rotate functions are primitive operations
> of the Signed_<n> and Unsigned_<n> families of types (RM B.2)
         ^^^^^^^^^^

A surprising mistake :-) It is of course the case that these
functions do NOT apply to signed numbers (where there meaning
would be obscure or at least implementation defined, because
of the sign bit issue).

One interesting bit of non-portability comes from whether it
is possible to define these operators for *USER* defined
unsigned types. The RM does not require this capability, but
in GNAT you can define your own intrinsic shift functions for
your own modular types, and GNAT will permit this. I do not
know if other Ada 95 compilers provide this capability.



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