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86 lines
2.4 KiB
86 lines
2.4 KiB
/* |
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* Copyright (c) 2011 Broadcom Corporation |
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* |
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* Permission to use, copy, modify, and/or distribute this software for any |
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* purpose with or without fee is hereby granted, provided that the above |
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* copyright notice and this permission notice appear in all copies. |
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* |
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES |
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF |
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY |
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* SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES |
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION |
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* OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN |
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* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. |
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*/ |
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
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#include <linux/module.h> |
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#include <linux/crc8.h> |
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#include <linux/printk.h> |
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/** |
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* crc8_populate_msb - fill crc table for given polynomial in reverse bit order. |
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* |
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* @table: table to be filled. |
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* @polynomial: polynomial for which table is to be filled. |
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*/ |
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void crc8_populate_msb(u8 table[CRC8_TABLE_SIZE], u8 polynomial) |
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{ |
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int i, j; |
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const u8 msbit = 0x80; |
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u8 t = msbit; |
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table[0] = 0; |
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for (i = 1; i < CRC8_TABLE_SIZE; i *= 2) { |
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t = (t << 1) ^ (t & msbit ? polynomial : 0); |
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for (j = 0; j < i; j++) |
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table[i+j] = table[j] ^ t; |
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} |
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} |
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EXPORT_SYMBOL(crc8_populate_msb); |
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/** |
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* crc8_populate_lsb - fill crc table for given polynomial in regular bit order. |
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* |
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* @table: table to be filled. |
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* @polynomial: polynomial for which table is to be filled. |
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*/ |
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void crc8_populate_lsb(u8 table[CRC8_TABLE_SIZE], u8 polynomial) |
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{ |
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int i, j; |
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u8 t = 1; |
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table[0] = 0; |
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for (i = (CRC8_TABLE_SIZE >> 1); i; i >>= 1) { |
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t = (t >> 1) ^ (t & 1 ? polynomial : 0); |
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for (j = 0; j < CRC8_TABLE_SIZE; j += 2*i) |
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table[i+j] = table[j] ^ t; |
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} |
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} |
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EXPORT_SYMBOL(crc8_populate_lsb); |
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/** |
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* crc8 - calculate a crc8 over the given input data. |
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* |
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* @table: crc table used for calculation. |
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* @pdata: pointer to data buffer. |
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* @nbytes: number of bytes in data buffer. |
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* @crc: previous returned crc8 value. |
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*/ |
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u8 crc8(const u8 table[CRC8_TABLE_SIZE], const u8 *pdata, size_t nbytes, u8 crc) |
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{ |
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/* loop over the buffer data */ |
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while (nbytes-- > 0) |
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crc = table[(crc ^ *pdata++) & 0xff]; |
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return crc; |
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} |
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EXPORT_SYMBOL(crc8); |
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MODULE_DESCRIPTION("CRC8 (by Williams, Ross N.) function"); |
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MODULE_AUTHOR("Broadcom Corporation"); |
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MODULE_LICENSE("Dual BSD/GPL");
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