[PATCH] lib/crc16: added crc16 algorithm. (7657ec1f) · Commits · e / devices / android_kernel_xiaomi_markw

include/linux/crc16.h

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+44 −0

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		/*
		* crc16.h - CRC-16 routine
		*
		* Implements the standard CRC-16, as used with 1-wire devices:
		* Width 16
		* Poly 0x8005 (x^16 + x^15 + x^2 + 1)
		* Init 0
		*
		* For 1-wire devices, the CRC is stored inverted, LSB-first
		*
		* Example buffer with the CRC attached:
		* 31 32 33 34 35 36 37 38 39 C2 44
		*
		* The CRC over a buffer with the CRC attached is 0xB001.
		* So, if (crc16(0, buf, size) == 0xB001) then the buffer is valid.
		*
		* Refer to "Application Note 937: Book of iButton Standards" for details.
		* http://www.maxim-ic.com/appnotes.cfm/appnote_number/937
		*
		* Copyright (c) 2005 Ben Gardner <bgardner@wabtec.com>
		*
		* This source code is licensed under the GNU General Public License,
		* Version 2. See the file COPYING for more details.
		*/

		#ifndef __CRC16_H
		#define __CRC16_H

		#include <linux/types.h>

		#define CRC16_INIT 0
		#define CRC16_VALID 0xb001

		extern u16 const crc16_table[256];

		extern u16 crc16(u16 crc, const u8 *buffer, size_t len);

		static inline u16 crc16_byte(u16 crc, const u8 data)
		{
		return (crc >> 8) ^ crc16_table[(crc ^ data) & 0xff];
		}

		#endif /* __CRC16_H */

lib/Kconfig

+8 −0

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		@@ -12,6 +12,14 @@ config CRC_CCITT
		the kernel tree does. Such modules that use library CRC-CCITT
		functions require M here.

		config CRC16
		tristate "CRC16 functions"
		help
		This option is provided for the case where no in-kernel-tree
		modules require CRC16 functions, but a module built outside
		the kernel tree does. Such modules that use library CRC16
		functions require M here.

		config CRC32
		tristate "CRC32 functions"
		default y

lib/Makefile

+2 −1

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		@@ -28,6 +28,7 @@ ifneq ($(CONFIG_HAVE_DEC_LOCK),y)
		endif

		obj-$(CONFIG_CRC_CCITT) += crc-ccitt.o
		obj-$(CONFIG_CRC16) += crc16.o
		obj-$(CONFIG_CRC32) += crc32.o
		obj-$(CONFIG_LIBCRC32C) += libcrc32c.o
		obj-$(CONFIG_GENERIC_IOMAP) += iomap.o

lib/crc16.c

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		/*
		* crc16.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/crc16.h>

		/** CRC table for the CRC-16. The poly is 0x8005 (x^16 + x^15 + x^2 + 1) */
		u16 const crc16_table[256] = {
		0x0000, 0xC0C1, 0xC181, 0x0140, 0xC301, 0x03C0, 0x0280, 0xC241,
		0xC601, 0x06C0, 0x0780, 0xC741, 0x0500, 0xC5C1, 0xC481, 0x0440,
		0xCC01, 0x0CC0, 0x0D80, 0xCD41, 0x0F00, 0xCFC1, 0xCE81, 0x0E40,
		0x0A00, 0xCAC1, 0xCB81, 0x0B40, 0xC901, 0x09C0, 0x0880, 0xC841,
		0xD801, 0x18C0, 0x1980, 0xD941, 0x1B00, 0xDBC1, 0xDA81, 0x1A40,
		0x1E00, 0xDEC1, 0xDF81, 0x1F40, 0xDD01, 0x1DC0, 0x1C80, 0xDC41,
		0x1400, 0xD4C1, 0xD581, 0x1540, 0xD701, 0x17C0, 0x1680, 0xD641,
		0xD201, 0x12C0, 0x1380, 0xD341, 0x1100, 0xD1C1, 0xD081, 0x1040,
		0xF001, 0x30C0, 0x3180, 0xF141, 0x3300, 0xF3C1, 0xF281, 0x3240,
		0x3600, 0xF6C1, 0xF781, 0x3740, 0xF501, 0x35C0, 0x3480, 0xF441,
		0x3C00, 0xFCC1, 0xFD81, 0x3D40, 0xFF01, 0x3FC0, 0x3E80, 0xFE41,
		0xFA01, 0x3AC0, 0x3B80, 0xFB41, 0x3900, 0xF9C1, 0xF881, 0x3840,
		0x2800, 0xE8C1, 0xE981, 0x2940, 0xEB01, 0x2BC0, 0x2A80, 0xEA41,
		0xEE01, 0x2EC0, 0x2F80, 0xEF41, 0x2D00, 0xEDC1, 0xEC81, 0x2C40,
		0xE401, 0x24C0, 0x2580, 0xE541, 0x2700, 0xE7C1, 0xE681, 0x2640,
		0x2200, 0xE2C1, 0xE381, 0x2340, 0xE101, 0x21C0, 0x2080, 0xE041,
		0xA001, 0x60C0, 0x6180, 0xA141, 0x6300, 0xA3C1, 0xA281, 0x6240,
		0x6600, 0xA6C1, 0xA781, 0x6740, 0xA501, 0x65C0, 0x6480, 0xA441,
		0x6C00, 0xACC1, 0xAD81, 0x6D40, 0xAF01, 0x6FC0, 0x6E80, 0xAE41,
		0xAA01, 0x6AC0, 0x6B80, 0xAB41, 0x6900, 0xA9C1, 0xA881, 0x6840,
		0x7800, 0xB8C1, 0xB981, 0x7940, 0xBB01, 0x7BC0, 0x7A80, 0xBA41,
		0xBE01, 0x7EC0, 0x7F80, 0xBF41, 0x7D00, 0xBDC1, 0xBC81, 0x7C40,
		0xB401, 0x74C0, 0x7580, 0xB541, 0x7700, 0xB7C1, 0xB681, 0x7640,
		0x7200, 0xB2C1, 0xB381, 0x7340, 0xB101, 0x71C0, 0x7080, 0xB041,
		0x5000, 0x90C1, 0x9181, 0x5140, 0x9301, 0x53C0, 0x5280, 0x9241,
		0x9601, 0x56C0, 0x5780, 0x9741, 0x5500, 0x95C1, 0x9481, 0x5440,
		0x9C01, 0x5CC0, 0x5D80, 0x9D41, 0x5F00, 0x9FC1, 0x9E81, 0x5E40,
		0x5A00, 0x9AC1, 0x9B81, 0x5B40, 0x9901, 0x59C0, 0x5880, 0x9841,
		0x8801, 0x48C0, 0x4980, 0x8941, 0x4B00, 0x8BC1, 0x8A81, 0x4A40,
		0x4E00, 0x8EC1, 0x8F81, 0x4F40, 0x8D01, 0x4DC0, 0x4C80, 0x8C41,
		0x4400, 0x84C1, 0x8581, 0x4540, 0x8701, 0x47C0, 0x4680, 0x8641,
		0x8201, 0x42C0, 0x4380, 0x8341, 0x4100, 0x81C1, 0x8081, 0x4040
		};
		EXPORT_SYMBOL(crc16_table);

		/**
		* Compute the CRC-16 for the data buffer
		*
		* @param crc previous CRC value
		* @param buffer data pointer
		* @param len number of bytes in the buffer
		* @return the updated CRC value
		*/
		u16 crc16(u16 crc, u8 const *buffer, size_t len)
		{
		while (len--)
		crc = crc16_byte(crc, *buffer++);
		return crc;
		}
		EXPORT_SYMBOL(crc16);

		MODULE_DESCRIPTION("CRC16 calculations");
		MODULE_LICENSE("GPL");