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Subject: Re: [PATCH] consolidate all within() implementations
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
       Harvey Harrison <harvey.harrison@gmail.com>,
       linux-kernel@vger.kernel.org
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Date: Wed, 21 May 2008 12:04:26 +0200
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>  
>  /**
> + * addr_within - check whether address is in start-and-end address range
> + * @addr: address
> + * @start: start address (included in range)
> + * @end: end address (excluded from range)
> + */
> +static inline int addr_within(const void *addr, const void *start,
> +			      const void *end)
> +{
> +	return ((unsigned long) addr >= (unsigned long) start) &&
> +	       ((unsigned long) addr < (unsigned long) end);
> +}
> +
> +/**
> + * addr_within_len - check whether address is in start-and-length address range
> + * @addr: address
> + * @start: start of range
> + * @len: number of bytes in range
> + */
> +static inline int addr_within_len(const void *addr, const void *start,
> +				  size_t len)
> +{
> +	return ((unsigned long) addr >= (unsigned long) start) &&
> +	       ((unsigned long) addr < ((unsigned long) start + len));
> +}

might be my braindamage, but I'd have written it like:

static inline int 
addr_within_len(const void *addr, const void *start, size_t len)
{
	return (unsigned long)addr - (unsigned long)start < len;
}

static inline int
addr_within(const void *add, const void *start, const void *end)
{
	return addr_within_len(addr, start, 
			(unsigned long)end - (unsigned long)start);
}