57 lines
1.1 KiB
C
57 lines
1.1 KiB
C
/*
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* Copyright (c) 2020 Intel Corporation
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* Copyright (c) 2017 Nordic Semiconductor ASA
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* Copyright (c) 2015 Runtime Inc
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#include <zephyr/sys/crc.h>
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static const uint8_t crc8_ccitt_small_table[16] = {
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0x00, 0x07, 0x0e, 0x09, 0x1c, 0x1b, 0x12, 0x15,
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0x38, 0x3f, 0x36, 0x31, 0x24, 0x23, 0x2a, 0x2d
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};
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uint8_t crc8_ccitt(uint8_t val, const void *buf, size_t cnt)
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{
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size_t i;
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const uint8_t *p = buf;
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for (i = 0; i < cnt; i++) {
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val ^= p[i];
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val = (val << 4) ^ crc8_ccitt_small_table[val >> 4];
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val = (val << 4) ^ crc8_ccitt_small_table[val >> 4];
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}
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return val;
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}
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uint8_t crc8(const uint8_t *src, size_t len, uint8_t polynomial, uint8_t initial_value,
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bool reversed)
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{
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uint8_t crc = initial_value;
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size_t i, j;
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for (i = 0; i < len; i++) {
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crc ^= src[i];
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for (j = 0; j < 8; j++) {
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if (reversed) {
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if (crc & 0x01) {
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crc = (crc >> 1) ^ polynomial;
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} else {
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crc >>= 1;
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}
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} else {
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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 <<= 1;
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}
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}
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}
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}
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return crc;
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}
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