Re: [KJ] [PATCH] add new macro BIT_S to include/linux/kernel.h

From: Michael Veeck <michael.veeck@gmx.net>
To: kernel-janitors@vger.kernel.org
Subject: Re: [KJ] [PATCH] add new macro BIT_S to include/linux/kernel.h
Date: Sat, 13 Aug 2005 23:11:08 +0000	[thread overview]
Message-ID: <42FE7E0C.90202@gmx.net> (raw)
In-Reply-To: <42FDD89B.1010106@gmx.net>

Alexey Dobriyan wrote:
> On Sat, Aug 13, 2005 at 01:25:15PM +0200, Michael Veeck wrote:
> 
>>adds a new macro for doing a bitshift. right now every subsystem defines 
>>its own macro (which all look the same) but this one also does overflow 
>>checking
> 
> 
> Checking?
> 
> $ cat -n test.c
>      1	#define BIT(x) (1ULL << (x))
>      2	#define BITS(x) (1ULL << ((x) % 64))
>      3	
>      4	int main(void)
>      5	{
>      6		BIT(65);
>      7		BITS(65);
>      8		return 0;
>      9	}
> $ gcc -o test test.c
> test.c: In function `main':
> test.c:6: warning: left shift count >= width of type
> 	<== ???
> 

okay, good point, but does that work even when the parameter of BIT isnt 
known at compile time?
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