50 lines
1.5 KiB
C
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;
|
|
}
|