Messages in this thread | | | Date | Wed, 3 Jun 2009 17:05:06 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH 01/10] crc-itu-t: add bit-reversed calculation |
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On Mon, 1 Jun 2009 18:54:42 +0400 Dmitry Eremin-Solenikov <dbaryshkov@gmail.com> wrote:
> From: Darren Salt <linux@youmustbejoking.demon.co.uk> > > .. > > static inline u16 crc_itu_t_byte(u16 crc, const u8 data) > { > return (crc << 8) ^ crc_itu_t_table[((crc >> 8) ^ data) & 0xff]; > } > > +static inline u16 crc_itu_t_bitreversed_byte(u16 crc, const u8 data) > +{ > + return (crc << 8) ^ crc_itu_t_table[((crc >> 8) ^ bitrev8(data)) & 0xff]; > +}
I suspect that inlining these was a mistake, but one which we make often.
> #endif /* CRC_ITU_T_H */ > > diff --git a/lib/crc-itu-t.c b/lib/crc-itu-t.c > index a63472b..5562fdd 100644 > --- a/lib/crc-itu-t.c > +++ b/lib/crc-itu-t.c > @@ -64,6 +64,24 @@ u16 crc_itu_t(u16 crc, const u8 *buffer, size_t len) > } > EXPORT_SYMBOL(crc_itu_t); > > +/** > + * crc_itu_t_bitreversed - Compute the CRC-ITU-T for the data buffer; > + * the buffer content is assumed to be bit-reversed
kerneldoc doesn't support the breaking of this information across multiple lines. It'll need to be done as a single 120-column line.
> + * @crc: previous CRC value > + * @buffer: data pointer > + * @len: number of bytes in the buffer > + * > + * Returns the updated CRC value > + */ > +u16 crc_itu_t_bitreversed(u16 crc, const u8 *buffer, size_t len) > +{ > + while (len--) > + crc = crc_itu_t_bitreversed_byte(crc, *buffer++); > + return crc; > +} > +EXPORT_SYMBOL(crc_itu_t_bitreversed);
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