Date: Wed, 14 Jan 1998 20:31:41 -0800 (PST)
Message-Id: <199801150431.UAA16364@adit.ap.net>
Mime-Version: 1.0
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To: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>, Noam Rotem <nrotem AT johnbryce DOT co DOT il>,
        djgpp AT delorie DOT com
From: Nate Eldredge <eldredge AT ap DOT net>
Subject: Re: Bit fields in djgpp
Precedence: bulk

At 02:03  1/14/1998 +0200, Eli Zaretskii wrote:
>
>On Wed, 14 Jan 1998, I wrote:
>
>> On Tue, 13 Jan 1998, Nate Eldredge wrote:
>> 
>> > Solution: Declare the bitfields as `unsigned'.
>> 
>> I'm not sure this solution is indeed required.  I think what Noam
>> reported was due to the effect of `printf', and the actual value
>> stored inside the variable was correct.
>
>Sorry, I was wrong.  The ANSI C Standard explicitly says that signed bit 
>fields of size N can be used to represent values in the range [0, 2^(N-1))
>so when N is 1, you cannot represent 1.  You need to make it unsigned, as 
>Nate suggested.
Oughtn't that to be:
[0..(2^(N-1))-1] ?
Because, for instance, a 16-bit signed value can only go up to 32767.

Also, 2^(N-1) for N=1 equals 2^0 = 1.

Or is the range not inclusive?
Or am I just confused??


Nate Eldredge
eldredge AT ap DOT net