mirror of
https://github.com/f4exb/sdrangel.git
synced 2025-11-03 21:20:31 -05:00
92 lines
3.1 KiB
C++
92 lines
3.1 KiB
C++
///////////////////////////////////////////////////////////////////////////////////
|
|
// Copyright (C) 2012 maintech GmbH, Otto-Hahn-Str. 15, 97204 Hoechberg, Germany //
|
|
// written by Christian Daniel //
|
|
// Copyright (C) 2015-2020 Edouard Griffiths, F4EXB <f4exb06@gmail.com> //
|
|
// Copyright (C) 2020 Jon Beniston, M7RCE <jon@beniston.com> //
|
|
// //
|
|
// 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 as 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 V3 for more details. //
|
|
// //
|
|
// You should have received a copy of the GNU General Public License //
|
|
// along with this program. If not, see <http://www.gnu.org/licenses/>. //
|
|
///////////////////////////////////////////////////////////////////////////////////
|
|
|
|
#include "crc.h"
|
|
|
|
// Reverse bit ordering
|
|
uint32_t crc::reverse(uint32_t val, int bits)
|
|
{
|
|
uint32_t temp;
|
|
int i;
|
|
|
|
temp = 0;
|
|
for (i = 0; i < bits; i++)
|
|
temp |= ((val >> i) & 1) << (bits - 1 - i);
|
|
return temp;
|
|
}
|
|
|
|
// Calculate CRC for specified number of bits
|
|
void crc::calculate(uint32_t data, int data_bits)
|
|
{
|
|
uint32_t tmp;
|
|
uint32_t mask;
|
|
uint32_t msb;
|
|
int bit, i;
|
|
|
|
if (m_msb_first)
|
|
{
|
|
mask = (1 << m_poly_bits) - 1;
|
|
msb = 1 << (m_poly_bits - 1);
|
|
tmp = m_crc ^ (data << (m_poly_bits - 8));
|
|
for (i = 0; i < data_bits; i++)
|
|
{
|
|
if (tmp & msb)
|
|
tmp = (tmp << 1) ^ m_polynomial;
|
|
else
|
|
tmp = tmp << 1;
|
|
tmp = tmp & mask;
|
|
}
|
|
m_crc = tmp;
|
|
}
|
|
else
|
|
{
|
|
tmp = m_crc;
|
|
for (i = 0; i < data_bits; i++) {
|
|
bit = ((data >> i) & 1) ^ (tmp & 1);
|
|
if (bit)
|
|
tmp = (tmp >> 1) ^ m_polynomial_rev;
|
|
else
|
|
tmp = tmp >> 1;
|
|
}
|
|
m_crc = tmp;
|
|
}
|
|
}
|
|
|
|
// Calculate CRC for specified array
|
|
void crc::calculate(const uint8_t *data, int length)
|
|
{
|
|
int i;
|
|
uint32_t mask1;
|
|
uint32_t mask2;
|
|
|
|
if (m_msb_first)
|
|
{
|
|
mask1 = (1 << m_poly_bits) - 1;
|
|
mask2 = 0xff << (m_poly_bits - 8);
|
|
for (i = 0; i < length; i++)
|
|
m_crc = mask1 & ((m_crc << 8) ^ m_lut[data[i] ^ ((m_crc & mask2) >> (m_poly_bits-8))]);
|
|
}
|
|
else
|
|
{
|
|
for (i = 0; i < length; i++)
|
|
m_crc = (m_crc >> 8) ^ m_lut[data[i] ^ (m_crc & 0xff)];
|
|
}
|
|
}
|