linux-kernel - Re: [patch v4 1/7] crc32: move-to-documentation.diff

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Date:	Tue, 9 Aug 2011 18:50:02 +0200
From:	Joakim Tjernlund <joakim.tjernlund@...nsmode.se>
To:	"George Spelvin" <linux@...izon.com>
Cc:	akpm@...ux-foundation.org, fzago@...temfabricworks.com,
	linux-kernel@...r.kernel.org, rdunlap@...otime.net,
	rpearson@...temfabricworks.com
Subject: Re: [patch v4 1/7] crc32: move-to-documentation.diff

"George Spelvin" <linux@...izon.com> wrote on 2011/08/09 13:45:04:
>
> Here's a hopefully-improved Documentation file, which explains the slicing
> algorithm as well.  As long as you have a big diff, it seems worth tweaking.
>
> You also might want to leave a pointer in lib/crc32.c to the relocated docs.
>
> (I'm just inclding the whole changed file because I assume it's easier
> to review that way; do you prefer a diff?)

Nice, reading this once again I think I found an old typo. See below

Perhaps Bob can add this addition to his patch series?

>
> === Cut here ===
...
> Or in little-endian:
> for (i = 0; i < input_bytes; i++) {
>    remainder ^= next_input_byte();
>    for (j = 0; j < 8; j++) {
>       multiple = (remainder & 1) ? CRCPOLY : 0;
>       remainder = (remainder << 1) ^ multiple;

Should not above line be:
       remainder = (remainder >> 1) ^ multiple;
?

>    }
> }
>
> If the input is a multiple of 32 bits, you can even XOR in a 32-bit
> word at a time and increase the inner loop count to 32.

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