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sdrangel/sdrbase/util/crc.h
Jon Beniston 72e4e684e2 ADS-B Demodulator updates.
Add OpenSky Network aircraft database support, for information about
aircraft model, owner, registration.
Add airline logos and country & military flags for display in the table.
Add OurAirports airport database support, to allow airports and ATC
frequencies to be displayed on the map.
Allow ATC frequency to be tuned by clicking on the map.
Add support for displaying flight paths on the map.
Allow columns in table to be rearranged and hidden.
Allow rows in table to be sorted by clicking on header.
Allow switching units from ft, kn, ft/min to m, kph, m/s
Allow aircraft timeout to be set by the user.
Allow font used for the table to be set by the user.
Add optional display of demodulator statistics.
Support multithreading in demodulator to reduce FIFO overflows.
Add support for demodulating all Mode-S frames and feeding them.
Add support for feeding in Beast hex format.
Allow option of correlating against full preamble or partial preamble.
Supporting highlighting of an aircraft in the table by selecting it on
the map.
Use difference of zeros and ones correlation, rather than absolute
threshold, to better account for varying conditions and make the
threshold easier to set.
Enable anti-aliasing for text on the map.
Improve CRC performance by 5x-10x.
Add HttpDownloadManager class to support downloading of files from the
web to disk.
2020-11-06 12:18:55 +00:00

133 lines
3.8 KiB
C++

///////////////////////////////////////////////////////////////////////////////////
// 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_poly_bits(poly_bits),
m_polynomial(polynomial),
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) {}
};
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