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From: Richard Heathfield on 3 Jun 2010 06:50
bart.c wrote:
>
<snip>

> It seems reasonable to be able to request 'a' to be exactly 16-bits on
> any machine, whether that is natural for the architecture on not.

I'm not entirely convinced that that /is/ a reasonable request. It is
perfectly reasonable to ask for it to be *at least* 16 bits.

How, precisely, would you implement your exactly-16-bit type on a
machine whose natural word size is 64? Such a machine does exist, and C
implementations for it have to jump through all kinds of crazy hoops to
give programmers the 8-bit char they expect. I would not like to be the
one to tell the compiler team "well done lads, but now there's this
bloke on Usenet who wants 16-bit short ints..."

--
Richard Heathfield <http://www.cpax.org.uk>
Email: -http://www. +rjh@
"Usenet is a strange place" - dmr 29 July 1999
Sig line vacant - apply within
From: Richard Heathfield on 3 Jun 2010 09:24
Dann Corbit wrote:
> In article <2qmdnQNJioRrFZrRnZ2dnUVZ8nmdnZ2d(a)bt.com>,
> rjh(a)see.sig.invalid says...
>> bart.c wrote:
>> <snip>
>>
>>> It seems reasonable to be able to request 'a' to be exactly 16-bits on
>>> any machine, whether that is natural for the architecture on not.
>> I'm not entirely convinced that that /is/ a reasonable request. It is
>> perfectly reasonable to ask for it to be *at least* 16 bits.
>>
>> How, precisely, would you implement your exactly-16-bit type on a
>> machine whose natural word size is 64?
>
> typedef struct Integer16 { signed value:16; } Integer16 ;

That would make even simple addition rather tedious:

Integer16 x = { 6 }; /* braces required */
Integer16 y = { 42 };
Integer16 z;

z.value = x.value + y.value;

Blech!

--
Richard Heathfield <http://www.cpax.org.uk>
Email: -http://www. +rjh@
"Usenet is a strange place" - dmr 29 July 1999
Sig line vacant - apply within
From: Willem on 3 Jun 2010 12:54
Richard Heathfield wrote:
) Dann Corbit wrote:
)> In article <2qmdnQNJioRrFZrRnZ2dnUVZ8nmdnZ2d(a)bt.com>,
)> rjh(a)see.sig.invalid says...
)>> How, precisely, would you implement your exactly-16-bit type on a
)>> machine whose natural word size is 64?
)>
)> typedef struct Integer16 { signed value:16; } Integer16 ;
)
) That would make even simple addition rather tedious:
)
) Integer16 x = { 6 }; /* braces required */
) Integer16 y = { 42 };
) Integer16 z;
)
) z.value = x.value + y.value;

How easy would it be to add that syntax to the language ?

Something like:

typedef signed value:16 Integer16;

Or simply
unsigned x:10 = 1000;
unsigned y:10 = 42;
unsigned z:10 = x + y; /* z is now 18 */

I'm not sure but I think that this is a syntax violation in C90/C99,
so it could be added as a feature quite easily, no ?


SaSW, Willem
--
Disclaimer: I am in no way responsible for any of the statements
made in the above text. For all I know I might be
drugged or something..
No I'm not paranoid. You all think I'm paranoid, don't you !
#EOT
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