Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764489AbZFRO1h (ORCPT ); Thu, 18 Jun 2009 10:27:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1761121AbZFRO0q (ORCPT ); Thu, 18 Jun 2009 10:26:46 -0400 Received: from mail-ew0-f210.google.com ([209.85.219.210]:58265 "EHLO mail-ew0-f210.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754835AbZFRO0h (ORCPT ); Thu, 18 Jun 2009 10:26:37 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=from:to:cc:subject:date:message-id:x-mailer:in-reply-to:references; b=JXT39LCvZd57i8WLlJF/rMytGSd8ckQGyvFsVLHpUxqwJvdqYOR3AxJgoGUENizyyP 0yOWwmeHjd5BH9y+sBf0VXGnBjAExDYDMH7VWRNGWpNsUxF3zUSzsRvg12nkv5PuMxbm 0gvpN/g2MKqPkDMUmCTW+b6f3vkdfpSTELoHA= From: Dmitry Eremin-Solenikov To: netdev@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Sergey Lapin , Darren Salt Subject: [PATCH 2/5] crc-itu-t: add bit-reversed calculation Date: Thu, 18 Jun 2009 18:26:14 +0400 Message-Id: <1245335177-16810-3-git-send-email-dbaryshkov@gmail.com> X-Mailer: git-send-email 1.6.3.1 In-Reply-To: <1245335177-16810-2-git-send-email-dbaryshkov@gmail.com> References: <1245335177-16810-1-git-send-email-dbaryshkov@gmail.com> <1245335177-16810-2-git-send-email-dbaryshkov@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2883 Lines: 99 From: Darren Salt Changes since original patch by Darren: * add 'select BITREVERSE' * fix kerneldoc Signed-off-by: Darren Salt Signed-off-by: Dmitry Eremin-Solenikov --- include/linux/crc-itu-t.h | 10 ++++++++++ lib/Kconfig | 1 + lib/crc-itu-t.c | 17 +++++++++++++++++ 3 files changed, 28 insertions(+), 0 deletions(-) diff --git a/include/linux/crc-itu-t.h b/include/linux/crc-itu-t.h index 84920f3..7b2b7ba 100644 --- a/include/linux/crc-itu-t.h +++ b/include/linux/crc-itu-t.h @@ -6,6 +6,9 @@ * Poly 0x0x1021 (x^16 + x^12 + x^15 + 1) * Init 0 * + * The bit-reversed buffer variants may be non-standard, but some firmware + * loaders require them. + * * This source code is licensed under the GNU General Public License, * Version 2. See the file COPYING for more details. */ @@ -14,15 +17,22 @@ #define CRC_ITU_T_H #include +#include extern u16 const crc_itu_t_table[256]; extern u16 crc_itu_t(u16 crc, const u8 *buffer, size_t len); +extern u16 crc_itu_t_bitreversed(u16 crc, const u8 *buffer, size_t len); 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]; +} + #endif /* CRC_ITU_T_H */ diff --git a/lib/Kconfig b/lib/Kconfig index 8ade0a7..0ec01c3 100644 --- a/lib/Kconfig +++ b/lib/Kconfig @@ -45,6 +45,7 @@ config CRC_T10DIF config CRC_ITU_T tristate "CRC ITU-T V.41 functions" + select BITREVERSE help This option is provided for the case where no in-kernel-tree modules require CRC ITU-T V.41 functions, but a module built outside diff --git a/lib/crc-itu-t.c b/lib/crc-itu-t.c index a63472b..a1422d8 100644 --- a/lib/crc-itu-t.c +++ b/lib/crc-itu-t.c @@ -64,6 +64,23 @@ 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 bit-reversed data buffer; + * + * @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); + MODULE_DESCRIPTION("CRC ITU-T V.41 calculations"); MODULE_LICENSE("GPL"); -- 1.6.3.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/