mirror of
https://github.com/f4exb/sdrangel.git
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133 lines
3.8 KiB
C++
133 lines
3.8 KiB
C++
///////////////////////////////////////////////////////////////////////////////////
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// Copyright (C) 2020 Jon Beniston, M7RCE //
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// //
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// This program is free software; you can redistribute it and/or modify //
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// it under the terms of the GNU General Public License as published by //
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// the Free Software Foundation as version 3 of the License, or //
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// (at your option) any later version. //
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// //
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// This program is distributed in the hope that it will be useful, //
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// but WITHOUT ANY WARRANTY; without even the implied warranty of //
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the //
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// GNU General Public License V3 for more details. //
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// //
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// You should have received a copy of the GNU General Public License //
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// along with this program. If not, see <http://www.gnu.org/licenses/>. //
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///////////////////////////////////////////////////////////////////////////////////
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#ifndef INCLUDE_CRC_H
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#define INCLUDE_CRC_H
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#include <stdint.h>
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#include "export.h"
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// Class to calculate arbitrary CRCs (up to 32-bits)
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class SDRBASE_API crc
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{
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public:
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// Create and initialise CRC with specified polynomial and parameters
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crc(int poly_bits, uint32_t polynomial, bool msb_first, uint32_t init_value, uint32_t final_xor) :
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m_polynomial(polynomial),
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m_poly_bits(poly_bits),
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m_msb_first(msb_first),
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m_init_value(init_value),
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m_final_xor(final_xor)
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{
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// Reverse polynomial for LSB first
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if (!msb_first)
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{
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int shift;
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shift = 32 - m_poly_bits;
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m_polynomial_rev = reverse (m_polynomial << shift, 32);
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}
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// Create LUT
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for (int i = 0; i < 256; i++)
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{
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m_crc = 0;
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calculate(i, 8);
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m_lut[i] = m_crc;
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}
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init();
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}
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// Initialise CRC state
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void init()
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{
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m_crc = m_init_value;
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}
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// Calculate CRC for supplied data
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void calculate(uint32_t data, int data_bits);
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void calculate(const uint8_t *data, int length);
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// Get final CRC
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uint32_t get()
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{
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uint32_t t;
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t = m_final_xor ^ m_crc;
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return t;
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}
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private:
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static uint32_t reverse(uint32_t val, int bits);
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uint32_t m_crc;
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uint32_t m_polynomial;
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uint32_t m_polynomial_rev;
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uint32_t m_poly_bits;
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bool m_msb_first;
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uint32_t m_init_value;
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uint32_t m_final_xor;
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uint32_t m_lut[256];
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};
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class SDRBASE_API crc16ansi : public crc
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{
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public:
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crc16ansi() : crc(16, 0x8005, false, 0x0000, 0) {}
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};
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class SDRBASE_API crc16ccitt : public crc
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{
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public:
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crc16ccitt() : crc(16, 0x1021, true, 0xffff, 0) {}
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};
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class SDRBASE_API crc16itut : public crc
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{
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public:
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crc16itut() : crc(16, 0x1021, false, 0x0000, 0) {}
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};
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class SDRBASE_API crc16x25 : public crc
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{
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public:
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crc16x25() : crc(16, 0x1021, false, 0xffff, 0xffff) {}
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};
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class SDRBASE_API crc32 : public crc
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{
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public:
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crc32() : crc(32, 0x04C11DB7, false, 0xffffffff, 0xffffffff) {}
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};
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// Should probably try to use SSE 4.2's CRC32C instruction if available
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// See _mm_crc32_u8 and _mm_crc32_u64 intrinsics
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class SDRBASE_API crc32c : public crc
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{
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public:
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crc32c() : crc(32, 0x1EDC6F41, false, 0xffffffff, 0) {}
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};
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// ADS-B - https://mode-s.org/decode/adsb/introduction.html
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class SDRBASE_API crcadsb : public crc
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{
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public:
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crcadsb() : crc(24, 0xfff409, true, 0, 0) {}
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};
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#endif
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