HackRF-Treasure-Chest/Software/portapack-mayhem/hackrf/firmware/common/crc.c
2022-09-22 09:26:57 -07:00

50 lines
1.5 KiB
C

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