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sdrangel/sdrbase/util/crc.h

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///////////////////////////////////////////////////////////////////////////////////
// Copyright (C) 2020 Jon Beniston, M7RCE //
// //
// 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/>. //
///////////////////////////////////////////////////////////////////////////////////
#ifndef INCLUDE_CRC_H
#define INCLUDE_CRC_H
#include <stdint.h>
#include "export.h"
// Class to calculate arbitrary CRCs (up to 32-bits)
class SDRBASE_API crc
{
public:
// Create and initialise CRC with specified polynomial and parameters
crc(int poly_bits, uint32_t polynomial, bool msb_first, uint32_t init_value, uint32_t final_xor) :
m_polynomial(polynomial),
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m_poly_bits(poly_bits),
m_msb_first(msb_first),
m_init_value(init_value),
m_final_xor(final_xor)
{
// Reverse polynomial for LSB first
if (!msb_first)
{
int shift;
shift = 32 - m_poly_bits;
m_polynomial_rev = reverse (m_polynomial << shift, 32);
}
// Create LUT
for (int i = 0; i < 256; i++)
{
m_crc = 0;
calculate(i, 8);
m_lut[i] = m_crc;
}
init();
}
// Initialise CRC state
void init()
{
m_crc = m_init_value;
}
// Calculate CRC for supplied data
void calculate(uint32_t data, int data_bits);
void calculate(const uint8_t *data, int length);
// Get final CRC
uint32_t get()
{
uint32_t t;
t = m_final_xor ^ m_crc;
return t;
}
private:
static uint32_t reverse(uint32_t val, int bits);
uint32_t m_crc;
uint32_t m_polynomial;
uint32_t m_polynomial_rev;
uint32_t m_poly_bits;
bool m_msb_first;
uint32_t m_init_value;
uint32_t m_final_xor;
uint32_t m_lut[256];
};
class SDRBASE_API crc16ansi : public crc
{
public:
crc16ansi() : crc(16, 0x8005, false, 0x0000, 0) {}
};
class SDRBASE_API crc16ccitt : public crc
{
public:
crc16ccitt() : crc(16, 0x1021, true, 0xffff, 0) {}
};
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class SDRBASE_API crc16itut : public crc
{
public:
crc16itut() : crc(16, 0x1021, false, 0x0000, 0) {}
};
class SDRBASE_API crc16x25 : public crc
{
public:
crc16x25() : crc(16, 0x1021, false, 0xffff, 0xffff) {}
};
class SDRBASE_API crc32 : public crc
{
public:
crc32() : crc(32, 0x04C11DB7, false, 0xffffffff, 0xffffffff) {}
};
// Should probably try to use SSE 4.2's CRC32C instruction if available
// See _mm_crc32_u8 and _mm_crc32_u64 intrinsics
class SDRBASE_API crc32c : public crc
{
public:
crc32c() : crc(32, 0x1EDC6F41, false, 0xffffffff, 0) {}
};
// ADS-B - https://mode-s.org/decode/adsb/introduction.html
class SDRBASE_API crcadsb : public crc
{
public:
crcadsb() : crc(24, 0xfff409, true, 0, 0) {}
};
#endif