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65 lines
2.5 KiB
C++
65 lines
2.5 KiB
C++
/*
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* Copyright (c) 2022, Sensirion AG
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* * Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* * Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* * Neither the name of Sensirion AG nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "SensirionCrc.h"
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uint8_t generateCRCGeneric(const uint8_t* data, size_t count, uint8_t init,
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uint8_t polynomial) {
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uint8_t crc = init;
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/* calculates 8-Bit checksum with given polynomial */
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for (size_t current_byte = 0; current_byte < count; ++current_byte) {
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crc ^= (data[current_byte]);
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for (uint8_t crc_bit = 8; crc_bit > 0; --crc_bit) {
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if (crc & 0x80)
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crc = (crc << 1) ^ polynomial;
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else
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crc = (crc << 1);
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}
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}
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return crc;
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}
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uint8_t generateCRC31_ff(const uint8_t* data, size_t count) {
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return generateCRCGeneric(data, count, 0xff, 0x31);
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}
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uint8_t generateCRC31_00(const uint8_t* data, size_t count) {
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return generateCRCGeneric(data, count, 0x00, 0x31);
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}
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uint8_t generateCRC(const uint8_t* data, size_t count, CrcPolynomial type) {
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if (CRC31_00 == type) {
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return generateCRC31_00(data, count);
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}
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return generateCRC31_ff(data, count);
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}
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