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Commit ad241528 authored by Jan Nikitenko's avatar Jan Nikitenko Committed by Linus Torvalds
Browse files

CRC7 support 



Add CRC7 routines, used for example in MMC over SPI communication.
Kerneldoc updates

[akpm@linux-foundation.org: fix funny mix of const and non-const]
Signed-off-by: default avatarJan Nikitenko <jan.nikitenko@gmail.com>
Signed-off-by: default avatarDavid Brownell <dbrownell@users.sourceforge.net>
Cc: "Randy.Dunlap" <rdunlap@xenotime.net>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent c06e677a

Documentation/DocBook/kernel-api.tmpl

+3 −1
Original line number Diff line number Diff line
@@ -139,8 +139,10 @@ X!Ilib/string.c 
!Elib/cmdline.c

     </sect1>



     <sect1><title>CRC Functions</title>

     <sect1 id="crc"><title>CRC Functions</title>

!Elib/crc7.c

!Elib/crc16.c

!Elib/crc-itu-t.c

!Elib/crc32.c

!Elib/crc-ccitt.c

     </sect1>

include/linux/crc7.h

0 → 100644
+14 −0
Original line number Diff line number Diff line 
#ifndef _LINUX_CRC7_H

#define _LINUX_CRC7_H

#include <linux/types.h>



extern const u8 crc7_syndrome_table[256];



static inline u8 crc7_byte(u8 crc, u8 data)

{

	return crc7_syndrome_table[(crc << 1) ^ data];

}



extern u8 crc7(u8 crc, const u8 *buffer, size_t len);



#endif

lib/Kconfig

+8 −0
Original line number Diff line number Diff line
@@ -41,6 +41,14 @@ config CRC32 
	  kernel tree does. Such modules that use library CRC32 functions

	  require M here.



config CRC7

	tristate "CRC7 functions"

	help

	  This option is provided for the case where no in-kernel-tree

	  modules require CRC7 functions, but a module built outside

	  the kernel tree does. Such modules that use library CRC7

	  functions require M here.



config LIBCRC32C

	tristate "CRC32c (Castagnoli, et al) Cyclic Redundancy-Check"

	help

lib/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -43,6 +43,7 @@ obj-$(CONFIG_CRC_CCITT) += crc-ccitt.o 
obj-$(CONFIG_CRC16)	+= crc16.o

obj-$(CONFIG_CRC_ITU_T)	+= crc-itu-t.o

obj-$(CONFIG_CRC32)	+= crc32.o

obj-$(CONFIG_CRC7)	+= crc7.o

obj-$(CONFIG_LIBCRC32C)	+= libcrc32c.o

obj-$(CONFIG_GENERIC_ALLOCATOR) += genalloc.o

lib/crc7.c

0 → 100644
+68 −0
Original line number Diff line number Diff line 
/*

 *      crc7.c

 *

 * This source code is licensed under the GNU General Public License,

 * Version 2. See the file COPYING for more details.

 */



#include <linux/types.h>

#include <linux/module.h>

#include <linux/crc7.h>





/* Table for CRC-7 (polynomial x^7 + x^3 + 1) */

const u8 crc7_syndrome_table[256] = {

	0x00, 0x09, 0x12, 0x1b, 0x24, 0x2d, 0x36, 0x3f,

	0x48, 0x41, 0x5a, 0x53, 0x6c, 0x65, 0x7e, 0x77,

	0x19, 0x10, 0x0b, 0x02, 0x3d, 0x34, 0x2f, 0x26,

	0x51, 0x58, 0x43, 0x4a, 0x75, 0x7c, 0x67, 0x6e,

	0x32, 0x3b, 0x20, 0x29, 0x16, 0x1f, 0x04, 0x0d,

	0x7a, 0x73, 0x68, 0x61, 0x5e, 0x57, 0x4c, 0x45,

	0x2b, 0x22, 0x39, 0x30, 0x0f, 0x06, 0x1d, 0x14,

	0x63, 0x6a, 0x71, 0x78, 0x47, 0x4e, 0x55, 0x5c,

	0x64, 0x6d, 0x76, 0x7f, 0x40, 0x49, 0x52, 0x5b,

	0x2c, 0x25, 0x3e, 0x37, 0x08, 0x01, 0x1a, 0x13,

	0x7d, 0x74, 0x6f, 0x66, 0x59, 0x50, 0x4b, 0x42,

	0x35, 0x3c, 0x27, 0x2e, 0x11, 0x18, 0x03, 0x0a,

	0x56, 0x5f, 0x44, 0x4d, 0x72, 0x7b, 0x60, 0x69,

	0x1e, 0x17, 0x0c, 0x05, 0x3a, 0x33, 0x28, 0x21,

	0x4f, 0x46, 0x5d, 0x54, 0x6b, 0x62, 0x79, 0x70,

	0x07, 0x0e, 0x15, 0x1c, 0x23, 0x2a, 0x31, 0x38,

	0x41, 0x48, 0x53, 0x5a, 0x65, 0x6c, 0x77, 0x7e,

	0x09, 0x00, 0x1b, 0x12, 0x2d, 0x24, 0x3f, 0x36,

	0x58, 0x51, 0x4a, 0x43, 0x7c, 0x75, 0x6e, 0x67,

	0x10, 0x19, 0x02, 0x0b, 0x34, 0x3d, 0x26, 0x2f,

	0x73, 0x7a, 0x61, 0x68, 0x57, 0x5e, 0x45, 0x4c,

	0x3b, 0x32, 0x29, 0x20, 0x1f, 0x16, 0x0d, 0x04,

	0x6a, 0x63, 0x78, 0x71, 0x4e, 0x47, 0x5c, 0x55,

	0x22, 0x2b, 0x30, 0x39, 0x06, 0x0f, 0x14, 0x1d,

	0x25, 0x2c, 0x37, 0x3e, 0x01, 0x08, 0x13, 0x1a,

	0x6d, 0x64, 0x7f, 0x76, 0x49, 0x40, 0x5b, 0x52,

	0x3c, 0x35, 0x2e, 0x27, 0x18, 0x11, 0x0a, 0x03,

	0x74, 0x7d, 0x66, 0x6f, 0x50, 0x59, 0x42, 0x4b,

	0x17, 0x1e, 0x05, 0x0c, 0x33, 0x3a, 0x21, 0x28,

	0x5f, 0x56, 0x4d, 0x44, 0x7b, 0x72, 0x69, 0x60,

	0x0e, 0x07, 0x1c, 0x15, 0x2a, 0x23, 0x38, 0x31,

	0x46, 0x4f, 0x54, 0x5d, 0x62, 0x6b, 0x70, 0x79

};

EXPORT_SYMBOL(crc7_syndrome_table);



/**

 * crc7 - update the CRC7 for the data buffer

 * @crc:     previous CRC7 value

 * @buffer:  data pointer

 * @len:     number of bytes in the buffer

 * Context: any

 *

 * Returns the updated CRC7 value.

 */

u8 crc7(u8 crc, const u8 *buffer, size_t len)

{

	while (len--)

		crc = crc7_byte(crc, *buffer++);

	return crc;

}

EXPORT_SYMBOL(crc7);



MODULE_DESCRIPTION("CRC7 calculations");

MODULE_LICENSE("GPL");