41 lines
1.1 KiB
C
41 lines
1.1 KiB
C
/*
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* Copyright (c) 2021 Workaround GmbH.
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#include <sys/crc.h>
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/* crc table generated from polynomial 0x1EDC6F41UL (Castagnoli) */
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static const uint32_t crc32c_table[16] = {
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0x00000000UL, 0x105EC76FUL, 0x20BD8EDEUL, 0x30E349B1UL,
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0x417B1DBCUL, 0x5125DAD3UL, 0x61C69362UL, 0x7198540DUL,
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0x82F63B78UL, 0x92A8FC17UL, 0xA24BB5A6UL, 0xB21572C9UL,
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0xC38D26C4UL, 0xD3D3E1ABUL, 0xE330A81AUL, 0xF36E6F75UL
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};
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/* This value needs to be XORed with the final crc value once crc for
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* the entire stream is calculated. This is a requirement of crc32c algo.
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*/
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#define CRC32C_XOR_OUT 0xFFFFFFFFUL
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/* The crc32c algorithm requires the below value as Init value at the
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* beginning of the stream.
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*/
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#define CRC32C_INIT 0xFFFFFFFFUL
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uint32_t crc32_c(uint32_t crc, const uint8_t *data,
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size_t len, bool first_pkt, bool last_pkt)
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{
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if (first_pkt) {
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crc = CRC32C_INIT;
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}
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for (size_t i = 0; i < len; i++) {
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crc = crc32c_table[(crc ^ data[i]) & 0x0F] ^ (crc >> 4);
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crc = crc32c_table[(crc ^ ((uint32_t)data[i] >> 4)) & 0x0F] ^ (crc >> 4);
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}
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return last_pkt ? (crc ^ CRC32C_XOR_OUT) : crc;
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}
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