Re: [RFC v2] Documentation about unaligned memory access

From: Jan Kara
Date: Wed Dec 05 2007 - 06:42:01 EST


A minor typo:

...
> Avoiding unaligned accesses
> ===========================
>
> The easiest way to avoid unaligned access is to use the get_unaligned() and
> put_unaligned() macros provided by the <asm/unaligned.h> header file.
>
> Going back to an earlier example of code that potentially causes unaligned
> access:
>
> void myfunc(u8 *data, u32 value)
> {
> [...]
> *((u32 *) data) = cpu_to_le32(value);
> [...]
> }
>
> To avoid the unaligned memory access, you would rewrite it as follows:
>
> void myfunc(u8 *data, u32 value)
> {
> [...]
> value = cpu_to_le32(value);
> put_unaligned(value, data);
> [...]
> }
>
> The get_unaligned() macro works similarly. Assuming 'data' is a pointer to
> memory and you wish to avoid unaligned access, its usage is as follows:
>
> u32 value = get_unaligned(data);
>
> These macros work work for memory accesses of any length (not just 32 bits as
^^^^^^^^^
remove one of them :)

Honza
--
Jan Kara <jack@xxxxxxx>
SuSE CR Labs
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