Re: Conversion from floating point to signed 16 bits

[Martin <martin.dowie@btopenworld.com>]

On May 20, 4:47 pm, Adam Beneschan <a...@irvine.com> wrote:
> On May 20, 8:23 am, Martin <martin.do...@btopenworld.com> wrote:
>
>
>
> > On May 20, 4:18 pm, "Jeffrey R. Carter"
>
> > <spam.jrcarter....@nospam.acm.org> wrote:
> > > Martin wrote:
>
> > > > Or better - just use package Interfaces instead...
>
> > > No. Interfaces.Unsigned_16 is a modular type. The OP's Unsigned_16 is a signed
> > > integer type.
>
> > > --
> > > Jeff Carter
> > > "English bed-wetting types."
> > > Monty Python & the Holy Grail
> > > 15
>
> > So it is!!
>
> > A rather poorly named type then...tricky to think of a better name
> > though - perhaps the Interfaces names should have been Modular_16 /
> > etc. Too late now...back to Int16 and Uint16 it is then...
>
> As Jeff said, the OP's Unsigned_16 is a "signed integer type"
> according to the definitions in the Ada standard, which defines two
> kinds of integer types, "signed" and "modular".  There is no
> "unsigned" integer type.  However, a type like Unsigned_16 will
> usually be implemented (on an 8-bit-byte-addressable machine) as a 16-
> bit unsigned integer (objects of the type will occupy exactly two
> bytes, and the code will use instructions that operate on 16-bit
> unsigned integers where possible, if such instructions exist).  To me,
> that makes it hard to criticize the choice of name---practically
> speaking, it's an unsigned 16-bit integer type in normal industry
> parlance, and we can't expect Ada programmers to know the details of
> the standard's terminology as well as we language lawyers do.  As for
> the complaint that the type name be confused with types in
> Interfaces---maybe, maybe not.  It depends on who'll be reading the
> code.  I don't think we can decree that every name defined by the
> Standard is off-limits for programming use, so we have to draw a line
> somewhere.
>
>                                    -- Adam

Yes, the names in Interfaces do match those used by the C-style of
languages but it's a shame that because those other languages don't
have the rich variety that Ada does that we end up with a bit of a
mismatch.

I'm so used to Unsigned_16/etc being modular that whenever I see them
that's what I expect.

Cheers
-- Martin