mirror of
https://github.com/RfidResearchGroup/proxmark3.git
synced 2024-11-10 17:49:32 +08:00
50 lines
1.6 KiB
C
50 lines
1.6 KiB
C
//-----------------------------------------------------------------------------
|
|
// Copyright (C) Proxmark3 contributors. See AUTHORS.md for details.
|
|
//
|
|
// 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 3 of the License, 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.
|
|
//
|
|
// See LICENSE.txt for the text of the license.
|
|
//-----------------------------------------------------------------------------
|
|
#include "crc32.h"
|
|
|
|
#define htole32(x) (x)
|
|
#define CRC32_PRESET 0xFFFFFFFF
|
|
|
|
static void crc32_byte(uint32_t *crc, const uint8_t value);
|
|
|
|
static void crc32_byte(uint32_t *crc, const uint8_t value) {
|
|
/* x32 + x26 + x23 + x22 + x16 + x12 + x11 + x10 + x8 + x7 + x5 + x4 + x2 + x + 1 */
|
|
const uint32_t poly = 0xEDB88320;
|
|
|
|
*crc ^= value;
|
|
for (int current_bit = 7; current_bit >= 0; current_bit--) {
|
|
int bit_out = (*crc) & 0x00000001;
|
|
*crc >>= 1;
|
|
if (bit_out)
|
|
*crc ^= poly;
|
|
}
|
|
}
|
|
|
|
void crc32_ex(const uint8_t *d, const size_t n, uint8_t *crc) {
|
|
uint32_t c = CRC32_PRESET;
|
|
for (size_t i = 0; i < n; i++) {
|
|
crc32_byte(&c, d[i]);
|
|
}
|
|
crc[0] = (uint8_t) c;
|
|
crc[1] = (uint8_t)(c >> 8);
|
|
crc[2] = (uint8_t)(c >> 16);
|
|
crc[3] = (uint8_t)(c >> 24);
|
|
}
|
|
|
|
|
|
void crc32_append(uint8_t *d, const size_t n) {
|
|
crc32_ex(d, n, d + n);
|
|
}
|