Enda Kilgarriff / platform_drivers

Update platform drivers

src/crc8.c@10:b5115cd6b916, 2020-06-17 (annotated)

Committer:
EndaKilgarriff
Date:
Wed Jun 17 14:54:14 2020 +0000
Revision:
10:b5115cd6b916
Parent:
9:9e247b9c9abf 
Roll back delay.cpp to previous version

Who changed what in which revision?

UserRevisionLine numberNew contents of line
EndaKilgarriff 9:9e247b9c9abf 1 /***************************************************************************//**
EndaKilgarriff 9:9e247b9c9abf 2 * @file crc8.c
EndaKilgarriff 9:9e247b9c9abf 3 * @brief Source file of CRC-8 computation.
EndaKilgarriff 9:9e247b9c9abf 4 * @author Darius Berghe (darius.berghe@analog.com)
EndaKilgarriff 9:9e247b9c9abf 5 ********************************************************************************
EndaKilgarriff 9:9e247b9c9abf 6 * Copyright 2020(c) Analog Devices, Inc.
EndaKilgarriff 9:9e247b9c9abf 7 *
EndaKilgarriff 9:9e247b9c9abf 8 * All rights reserved.
EndaKilgarriff 9:9e247b9c9abf 9 *
EndaKilgarriff 9:9e247b9c9abf 10 * Redistribution and use in source and binary forms, with or without
EndaKilgarriff 9:9e247b9c9abf 11 * modification, are permitted provided that the following conditions are met:
EndaKilgarriff 9:9e247b9c9abf 12 * - Redistributions of source code must retain the above copyright
EndaKilgarriff 9:9e247b9c9abf 13 * notice, this list of conditions and the following disclaimer.
EndaKilgarriff 9:9e247b9c9abf 14 * - Redistributions in binary form must reproduce the above copyright
EndaKilgarriff 9:9e247b9c9abf 15 * notice, this list of conditions and the following disclaimer in
EndaKilgarriff 9:9e247b9c9abf 16 * the documentation and/or other materials provided with the
EndaKilgarriff 9:9e247b9c9abf 17 * distribution.
EndaKilgarriff 9:9e247b9c9abf 18 * - Neither the name of Analog Devices, Inc. nor the names of its
EndaKilgarriff 9:9e247b9c9abf 19 * contributors may be used to endorse or promote products derived
EndaKilgarriff 9:9e247b9c9abf 20 * from this software without specific prior written permission.
EndaKilgarriff 9:9e247b9c9abf 21 * - The use of this software may or may not infringe the patent rights
EndaKilgarriff 9:9e247b9c9abf 22 * of one or more patent holders. This license does not release you
EndaKilgarriff 9:9e247b9c9abf 23 * from the requirement that you obtain separate licenses from these
EndaKilgarriff 9:9e247b9c9abf 24 * patent holders to use this software.
EndaKilgarriff 9:9e247b9c9abf 25 * - Use of the software either in source or binary form, must be run
EndaKilgarriff 9:9e247b9c9abf 26 * on or directly connected to an Analog Devices Inc. component.
EndaKilgarriff 9:9e247b9c9abf 27 *
EndaKilgarriff 9:9e247b9c9abf 28 * THIS SOFTWARE IS PROVIDED BY ANALOG DEVICES "AS IS" AND ANY EXPRESS OR
EndaKilgarriff 9:9e247b9c9abf 29 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, NON-INFRINGEMENT,
EndaKilgarriff 9:9e247b9c9abf 30 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
EndaKilgarriff 9:9e247b9c9abf 31 * IN NO EVENT SHALL ANALOG DEVICES BE LIABLE FOR ANY DIRECT, INDIRECT,
EndaKilgarriff 9:9e247b9c9abf 32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
EndaKilgarriff 9:9e247b9c9abf 33 * LIMITED TO, INTELLECTUAL PROPERTY RIGHTS, PROCUREMENT OF SUBSTITUTE GOODS OR
EndaKilgarriff 9:9e247b9c9abf 34 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
EndaKilgarriff 9:9e247b9c9abf 35 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
EndaKilgarriff 9:9e247b9c9abf 36 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
EndaKilgarriff 9:9e247b9c9abf 37 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
EndaKilgarriff 9:9e247b9c9abf 38 *******************************************************************************/
EndaKilgarriff 9:9e247b9c9abf 39 #include "crc8.h"
EndaKilgarriff 9:9e247b9c9abf 40
EndaKilgarriff 9:9e247b9c9abf 41 /***************************************************************************//**
EndaKilgarriff 9:9e247b9c9abf 42 * @brief Creates the CRC-8 lookup table for a given polynomial.
EndaKilgarriff 9:9e247b9c9abf 43 *
EndaKilgarriff 9:9e247b9c9abf 44 * @param table - Pointer to a CRC-8 lookup table to write to.
EndaKilgarriff 9:9e247b9c9abf 45 * @param polynomial - msb-first representation of desired polynomial.
EndaKilgarriff 9:9e247b9c9abf 46 *
EndaKilgarriff 9:9e247b9c9abf 47 * Polynomials in CRC algorithms are typically represented as shown below.
EndaKilgarriff 9:9e247b9c9abf 48 *
EndaKilgarriff 9:9e247b9c9abf 49 * poly = x^8 + x^2 + x^1 + 1
EndaKilgarriff 9:9e247b9c9abf 50 *
EndaKilgarriff 9:9e247b9c9abf 51 * Using msb-first direction, x^7 maps to the msb.
EndaKilgarriff 9:9e247b9c9abf 52 *
EndaKilgarriff 9:9e247b9c9abf 53 * msb first: poly = (1)00000111 = 0x07
EndaKilgarriff 9:9e247b9c9abf 54 *
EndaKilgarriff 9:9e247b9c9abf 55 * @return None.
EndaKilgarriff 9:9e247b9c9abf 56 *******************************************************************************/
EndaKilgarriff 9:9e247b9c9abf 57 void crc8_populate_msb(uint8_t * table, const uint8_t polynomial)
EndaKilgarriff 9:9e247b9c9abf 58 {
EndaKilgarriff 9:9e247b9c9abf 59 if (!table)
EndaKilgarriff 9:9e247b9c9abf 60 return;
EndaKilgarriff 9:9e247b9c9abf 61
EndaKilgarriff 9:9e247b9c9abf 62 for (int16_t n = 0; n < CRC8_TABLE_SIZE; n++) {
EndaKilgarriff 9:9e247b9c9abf 63 uint8_t currByte = (uint8_t)n;
EndaKilgarriff 9:9e247b9c9abf 64 for (uint8_t bit = 0; bit < 8; bit++) {
EndaKilgarriff 9:9e247b9c9abf 65 if ((currByte & 0x80) != 0) {
EndaKilgarriff 9:9e247b9c9abf 66 currByte <<= 1;
EndaKilgarriff 9:9e247b9c9abf 67 currByte ^= polynomial;
EndaKilgarriff 9:9e247b9c9abf 68 } else {
EndaKilgarriff 9:9e247b9c9abf 69 currByte <<= 1;
EndaKilgarriff 9:9e247b9c9abf 70 }
EndaKilgarriff 9:9e247b9c9abf 71 }
EndaKilgarriff 9:9e247b9c9abf 72 table[n] = currByte;
EndaKilgarriff 9:9e247b9c9abf 73 }
EndaKilgarriff 9:9e247b9c9abf 74 }
EndaKilgarriff 9:9e247b9c9abf 75
EndaKilgarriff 9:9e247b9c9abf 76 /***************************************************************************//**
EndaKilgarriff 9:9e247b9c9abf 77 * @brief Computes the CRC-8 over a buffer of data.
EndaKilgarriff 9:9e247b9c9abf 78 *
EndaKilgarriff 9:9e247b9c9abf 79 * @param table - Pointer to a CRC-8 lookup table for the desired polynomial.
EndaKilgarriff 9:9e247b9c9abf 80 * @param pdata - Pointer to 8-bit data buffer.
EndaKilgarriff 9:9e247b9c9abf 81 * @param nbytes - Number of bytes to compute the CRC-8 over.
EndaKilgarriff 9:9e247b9c9abf 82 * @param crc - Initial value for the CRC-8 computation. Can be used to
EndaKilgarriff 9:9e247b9c9abf 83 * cascade calls to this function by providing a previous
EndaKilgarriff 9:9e247b9c9abf 84 * output of this function as the crc parameter.
EndaKilgarriff 9:9e247b9c9abf 85 *
EndaKilgarriff 9:9e247b9c9abf 86 * @return crc - Computed CRC-8 value.
EndaKilgarriff 9:9e247b9c9abf 87 *******************************************************************************/
EndaKilgarriff 9:9e247b9c9abf 88 uint8_t crc8(const uint8_t * table, const uint8_t *pdata, size_t nbytes,
EndaKilgarriff 9:9e247b9c9abf 89 uint8_t crc)
EndaKilgarriff 9:9e247b9c9abf 90 {
EndaKilgarriff 9:9e247b9c9abf 91 unsigned int idx;
EndaKilgarriff 9:9e247b9c9abf 92
EndaKilgarriff 9:9e247b9c9abf 93 while (nbytes--) {
EndaKilgarriff 9:9e247b9c9abf 94 idx = (crc ^ *pdata);
EndaKilgarriff 9:9e247b9c9abf 95 crc = (table[idx]) & 0xff;
EndaKilgarriff 9:9e247b9c9abf 96 pdata++;
EndaKilgarriff 9:9e247b9c9abf 97 }
EndaKilgarriff 9:9e247b9c9abf 98
EndaKilgarriff 9:9e247b9c9abf 99 return crc;
EndaKilgarriff 9:9e247b9c9abf 100 }