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    SubjectRe: [RFC] Documentation about unaligned memory access
    On Fri, 23 November 2007 00:15:53 +0000, Daniel Drake wrote:
    > What's the definition of an unaligned access?
    > =============================================
    > Unaligned memory accesses occur when you try to read N bytes of data starting
    > from an address that is not evenly divisible by N (i.e. addr % N != 0).
    > For example, reading 4 bytes of data from address 0x10000004 is fine, but
    > reading 4 bytes of data from address 0x10000005 would be an unaligned memory
    > access.

    The wording could also apply to a DMA of 8k from a 4k-aligned address.
    But I don't have a good idea how to improve it.

    > It's safe to assume that memcpy will always copy bytewise and hence will
    > never cause an unaligned access.

    s/always copy/always behave as if copying/

    memcpy usually copies at least wordwise, possibly even in bigger chunks.
    But that is just the inner loop. Unaligned bytes at the beginning/end
    receive special treatment.


    The rabbit runs faster than the fox, because the rabbit is rinning for
    his life while the fox is only running for his dinner.
    -- Aesop
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      Last update: 2007-11-30 09:27    [W:0.020 / U:87.256 seconds]
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