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lookup table based crc-8 implementation
This is code compatible with linux crc8.h although the implementation is somewhat different. This implementation is supposed to replace all crc-8 implementations in no-OS drivers which are all duplicates of each other. By comparing the performance of this new implementation with the old one on an x86 machine and on large sample sizes, it seems the new implementation is faster by a factor of 13. Signed-off-by: Darius Berghe <[email protected]>
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| /***************************************************************************//** | ||
| * @file crc.h | ||
| * @brief Generic header file for all CRC computation algorithms. | ||
| * @author Darius Berghe ([email protected]) | ||
| ******************************************************************************** | ||
| * Copyright 2020(c) Analog Devices, Inc. | ||
| * | ||
| * All rights reserved. | ||
| * | ||
| * Redistribution and use in source and binary forms, with or without | ||
| * modification, are permitted provided that the following conditions are met: | ||
| * - Redistributions of source code must retain the above copyright | ||
| * notice, this list of conditions and the following disclaimer. | ||
| * - Redistributions in binary form must reproduce the above copyright | ||
| * notice, this list of conditions and the following disclaimer in | ||
| * the documentation and/or other materials provided with the | ||
| * distribution. | ||
| * - Neither the name of Analog Devices, Inc. nor the names of its | ||
| * contributors may be used to endorse or promote products derived | ||
| * from this software without specific prior written permission. | ||
| * - The use of this software may or may not infringe the patent rights | ||
| * of one or more patent holders. This license does not release you | ||
| * from the requirement that you obtain separate licenses from these | ||
| * patent holders to use this software. | ||
| * - Use of the software either in source or binary form, must be run | ||
| * on or directly connected to an Analog Devices Inc. component. | ||
| * | ||
| * THIS SOFTWARE IS PROVIDED BY ANALOG DEVICES "AS IS" AND ANY EXPRESS OR | ||
| * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, NON-INFRINGEMENT, | ||
| * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | ||
| * IN NO EVENT SHALL ANALOG DEVICES BE LIABLE FOR ANY DIRECT, INDIRECT, | ||
| * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT | ||
| * LIMITED TO, INTELLECTUAL PROPERTY RIGHTS, PROCUREMENT OF SUBSTITUTE GOODS OR | ||
| * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER | ||
| * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, | ||
| * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE | ||
| * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | ||
| *******************************************************************************/ | ||
| #ifndef __CRC_H | ||
| #define __CRC_H | ||
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|
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| #include "crc8.h" | ||
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| #endif // __CRC_H |
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| /***************************************************************************//** | ||
| * @file crc8.h | ||
| * @brief Header file of CRC-8 computation. | ||
| * @author Darius Berghe ([email protected]) | ||
| ******************************************************************************** | ||
| * Copyright 2020(c) Analog Devices, Inc. | ||
| * | ||
| * All rights reserved. | ||
| * | ||
| * Redistribution and use in source and binary forms, with or without | ||
| * modification, are permitted provided that the following conditions are met: | ||
| * - Redistributions of source code must retain the above copyright | ||
| * notice, this list of conditions and the following disclaimer. | ||
| * - Redistributions in binary form must reproduce the above copyright | ||
| * notice, this list of conditions and the following disclaimer in | ||
| * the documentation and/or other materials provided with the | ||
| * distribution. | ||
| * - Neither the name of Analog Devices, Inc. nor the names of its | ||
| * contributors may be used to endorse or promote products derived | ||
| * from this software without specific prior written permission. | ||
| * - The use of this software may or may not infringe the patent rights | ||
| * of one or more patent holders. This license does not release you | ||
| * from the requirement that you obtain separate licenses from these | ||
| * patent holders to use this software. | ||
| * - Use of the software either in source or binary form, must be run | ||
| * on or directly connected to an Analog Devices Inc. component. | ||
| * | ||
| * THIS SOFTWARE IS PROVIDED BY ANALOG DEVICES "AS IS" AND ANY EXPRESS OR | ||
| * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, NON-INFRINGEMENT, | ||
| * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | ||
| * IN NO EVENT SHALL ANALOG DEVICES BE LIABLE FOR ANY DIRECT, INDIRECT, | ||
| * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT | ||
| * LIMITED TO, INTELLECTUAL PROPERTY RIGHTS, PROCUREMENT OF SUBSTITUTE GOODS OR | ||
| * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER | ||
| * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, | ||
| * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE | ||
| * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | ||
| *******************************************************************************/ | ||
| #ifndef __CRC8_H | ||
| #define __CRC8_H | ||
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|
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| #include <stdint.h> | ||
| #include <stddef.h> | ||
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| #define CRC8_TABLE_SIZE 256 | ||
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| #define DECLARE_CRC8_TABLE(_table) \ | ||
| static uint8_t _table[CRC8_TABLE_SIZE] | ||
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| void crc8_populate_msb(uint8_t * table, const uint8_t polynomial); | ||
| uint8_t crc8(const uint8_t * table, const uint8_t *pdata, size_t nbytes, | ||
| uint8_t crc); | ||
|
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| #endif // __CRC8_H |
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| /***************************************************************************//** | ||
| * @file crc8.c | ||
| * @brief Source file of CRC-8 computation. | ||
| * @author Darius Berghe ([email protected]) | ||
| ******************************************************************************** | ||
| * Copyright 2020(c) Analog Devices, Inc. | ||
| * | ||
| * All rights reserved. | ||
| * | ||
| * Redistribution and use in source and binary forms, with or without | ||
| * modification, are permitted provided that the following conditions are met: | ||
| * - Redistributions of source code must retain the above copyright | ||
| * notice, this list of conditions and the following disclaimer. | ||
| * - Redistributions in binary form must reproduce the above copyright | ||
| * notice, this list of conditions and the following disclaimer in | ||
| * the documentation and/or other materials provided with the | ||
| * distribution. | ||
| * - Neither the name of Analog Devices, Inc. nor the names of its | ||
| * contributors may be used to endorse or promote products derived | ||
| * from this software without specific prior written permission. | ||
| * - The use of this software may or may not infringe the patent rights | ||
| * of one or more patent holders. This license does not release you | ||
| * from the requirement that you obtain separate licenses from these | ||
| * patent holders to use this software. | ||
| * - Use of the software either in source or binary form, must be run | ||
| * on or directly connected to an Analog Devices Inc. component. | ||
| * | ||
| * THIS SOFTWARE IS PROVIDED BY ANALOG DEVICES "AS IS" AND ANY EXPRESS OR | ||
| * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, NON-INFRINGEMENT, | ||
| * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | ||
| * IN NO EVENT SHALL ANALOG DEVICES BE LIABLE FOR ANY DIRECT, INDIRECT, | ||
| * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT | ||
| * LIMITED TO, INTELLECTUAL PROPERTY RIGHTS, PROCUREMENT OF SUBSTITUTE GOODS OR | ||
| * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER | ||
| * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, | ||
| * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE | ||
| * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | ||
| *******************************************************************************/ | ||
| #include "crc8.h" | ||
|
|
||
| /***************************************************************************//** | ||
| * @brief Creates the CRC-8 lookup table for a given polynomial. | ||
| * | ||
| * @param table - Pointer to a CRC-8 lookup table to write to. | ||
| * @param polynomial - msb-first representation of desired polynomial. | ||
| * | ||
| * Polynomials in CRC algorithms are typically represented as shown below. | ||
| * | ||
| * poly = x^8 + x^2 + x^1 + 1 | ||
| * | ||
| * Using msb-first direction, x^7 maps to the msb. | ||
| * | ||
| * msb first: poly = (1)00000111 = 0x07 | ||
| * | ||
| * @return None. | ||
| *******************************************************************************/ | ||
| void crc8_populate_msb(uint8_t * table, const uint8_t polynomial) | ||
| { | ||
| if (!table) | ||
| return; | ||
|
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| for (int16_t n = 0; n < CRC8_TABLE_SIZE; n++) { | ||
| uint8_t currByte = (uint8_t)n; | ||
| for (uint8_t bit = 0; bit < 8; bit++) { | ||
| if ((currByte & 0x80) != 0) { | ||
| currByte <<= 1; | ||
| currByte ^= polynomial; | ||
| } else { | ||
| currByte <<= 1; | ||
| } | ||
| } | ||
| table[n] = currByte; | ||
| } | ||
| } | ||
|
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| /***************************************************************************//** | ||
| * @brief Computes the CRC-8 over a buffer of data. | ||
| * | ||
| * @param table - Pointer to a CRC-8 lookup table for the desired polynomial. | ||
| * @param pdata - Pointer to 8-bit data buffer. | ||
| * @param nbytes - Number of bytes to compute the CRC-8 over. | ||
| * @param crc - Initial value for the CRC-8 computation. Can be used to | ||
| * cascade calls to this function by providing a previous | ||
| * output of this function as the crc parameter. | ||
| * | ||
| * @return crc - Computed CRC-8 value. | ||
| *******************************************************************************/ | ||
| uint8_t crc8(const uint8_t * table, const uint8_t *pdata, size_t nbytes, | ||
| uint8_t crc) | ||
| { | ||
| unsigned int idx; | ||
|
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| while (nbytes--) { | ||
| idx = (crc ^ *pdata); | ||
| crc = (table[idx]) & 0xff; | ||
| pdata++; | ||
| } | ||
|
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| return crc; | ||
| } |