From: "Valdis Klētnieks" <valdis.kletnieks@vt.edu>
To: carver <carver.lio@hotmail.com>
Cc: kernelnewbies@kernelnewbies.org
Subject: Re: How to understand the comment of macro *compute_indices*?
Date: Mon, 13 Jul 2020 22:21:13 -0400 [thread overview]
Message-ID: <431735.1594693273@turing-police> (raw)
In-Reply-To: <KL1PR03MB49840A52005FD59C2D2FE6999A600@KL1PR03MB4984.apcprd03.prod.outlook.com>
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On Tue, 14 Jul 2020 07:54:04 +0800, carver said:
> Hello,
>
> Macro *compute_indices* in arch/arm64/kernel/head.S have a comment
> as shown below:
> mov \istart, \ptrs
> mul \istart, \istart, \count
> add \iend, \iend, \istart // iend += (count - 1) * ptrs
>
> I am wondering whether this comment should be change to
> "iend += count * ptrs".
Examine the uses of the macro, and see where they expect the result
to be pointing if there is exactly one entry. (Hint - what's the address of
the first entry of a C array, and what's the next location after the array,
and how would the corresponding C code for iterating across the array
have as the termination condition?)
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prev parent reply other threads:[~2020-07-14 2:21 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-13 23:54 How to understand the comment of macro *compute_indices*? carver
2020-07-14 2:21 ` Valdis Klētnieks [this message]
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