51 lines
1.5 KiB
C
51 lines
1.5 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/***************************************************************************
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* Copyright (C) 2013-2014 by Franck Jullien *
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* elec4fun@gmail.com *
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* *
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* Copyright (C) 2022 Otto-von-Guericke-Universität Magdeburg *
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* marian.buschsieweke@ovgu.de *
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***************************************************************************/
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include "crc32.h"
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#include <stdint.h>
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#include <stddef.h>
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static uint32_t crc_le_step(uint32_t poly, uint32_t crc, uint32_t data_in,
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unsigned int data_bits)
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{
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for (unsigned int i = 0; i < data_bits; i++) {
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uint32_t d, c;
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d = ((data_in >> i) & 0x1) ? 0xffffffff : 0;
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c = (crc & 0x1) ? 0xffffffff : 0;
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crc = crc >> 1;
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crc = crc ^ ((d ^ c) & poly);
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}
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return crc;
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}
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uint32_t crc32_le(uint32_t poly, uint32_t seed, const void *_data,
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size_t data_len)
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{
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if (((uintptr_t)_data & 0x3) || (data_len & 0x3)) {
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/* data is unaligned, processing data one byte at a time */
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const uint8_t *data = _data;
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for (size_t i = 0; i < data_len; i++)
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seed = crc_le_step(poly, seed, data[i], 8);
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} else {
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/* data is aligned, processing 32 bit at a time */
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data_len >>= 2;
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const uint32_t *data = _data;
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for (size_t i = 0; i < data_len; i++)
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seed = crc_le_step(poly, seed, data[i], 32);
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}
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return seed;
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}
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