50 lines
1.5 KiB
C
50 lines
1.5 KiB
C
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/*
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* Copyright 2019 Jared Boone <jared@sharebrained.com>
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*
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* This file is part of HackRF.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; see the file COPYING. If not, write to
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* the Free Software Foundation, Inc., 51 Franklin Street,
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* Boston, MA 02110-1301, USA.
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*/
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#include "crc.h"
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#include <stdbool.h>
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void crc32_init(crc32_t* const crc) {
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crc->remainder = 0xffffffff;
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crc->reversed_polynomial = 0xedb88320;
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crc->final_xor = 0xffffffff;
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}
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void crc32_update(crc32_t* const crc, const uint8_t* const data, const size_t byte_count) {
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uint32_t remainder = crc->remainder;
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const size_t bit_count = byte_count * 8;
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for(size_t bit_n=0; bit_n<bit_count; bit_n++) {
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const bool bit_in = data[bit_n >> 3] & (1 << (bit_n & 7));
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remainder ^= (bit_in ? 1 : 0);
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const bool bit_out = (remainder & 1);
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remainder >>= 1;
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if( bit_out ) {
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remainder ^= crc->reversed_polynomial;
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}
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}
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crc->remainder = remainder;
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}
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uint32_t crc32_digest(const crc32_t* const crc) {
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return crc->remainder ^ crc->final_xor;
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}
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