Newsgroups: comp.lang.c
Path: utzoo!utgpu!watserv1!watmath!datangua
From: datangua@watmath.waterloo.edu (David Tanguay)
Subject: Re: What breaks? (was Re: 64 bit longs?)
Organization: University of Waterloo
Date: Fri, 18 Jan 91 09:41:33 GMT
Message-ID: <1991Jan18.094133.16879@watmath.waterloo.edu>
References: <54379@eerie.acsu.Buffalo.EDU> <1991Jan15.053356.2631@zoo.toronto.edu> <1991Jan15.202123.14223@gjetor.geac.COM> <14890@smoke.brl.mil> <1991Jan18.044948.27943@zoo.toronto.edu>
Lines: 32

In article <1991Jan18.044948.27943@zoo.toronto.edu> henry@zoo.toronto.edu (Henry Spencer) writes:
>In article <14890@smoke.brl.mil> gwyn@smoke.brl.mil (Doug Gwyn) writes:
>>There is no portable way to declare any integral type constrained to use
>>precisely 32 bits in its representation.
>
>There is no portable way to declare a type with *exactly* 32 bits, and
>a TCP/IP sequence number (for example) is exactly 32, no more.

How about: (Standard C only)

typedef struct { long it:32; } net32_t;
#define net32_t(var) var.it

and then all accesses to variables are wrapped in net32_t(var).

	void
happy( void )
{
	net32_t it;

	...
	net32_t(it) = 123456;
	++net32_t(it);
	net32_t(some_global) = net32_t(it) + 42;
	...
}

I don't like sticking the 32 in the type name, since that may change,
so just consider the above as an illustration of a technique.
Ugly, I think, but it should accomplish what you want.
-- 
David Tanguay            Software Development Group, University of Waterloo