mirror of https://github.com/g4klx/MMDVM.git
159 lines
3.4 KiB
C++
159 lines
3.4 KiB
C++
/*
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* Copyright (C) 2020 by Jonathan Naylor G4KLX
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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; either version 2 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 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, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include "Config.h"
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#include "Globals.h"
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#include "FMCTCSSRX.h"
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const struct CTCSS_TABLE {
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uint8_t frequency;
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q31_t coeff;
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} CTCSS_TABLE_DATA[] = {
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{ 67U, 131052},
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{ 69U, 131051},
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{ 71U, 131049},
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{ 74U, 131048},
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{ 77U, 131046},
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{ 79U, 131044},
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{ 82U, 131042},
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{ 85U, 131040},
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{ 88U, 131037},
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{ 91U, 131035},
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{ 94U, 131032},
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{ 97U, 131030},
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{100U, 131028},
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{103U, 131024},
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{107U, 131021},
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{110U, 131017},
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{114U, 131013},
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{118U, 131009},
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{123U, 131005},
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{127U, 131000},
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{131U, 130994},
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{136U, 130989},
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{141U, 130983},
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{146U, 130977},
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{151U, 130970},
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{156U, 130962},
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{159U, 130958},
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{162U, 130954},
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{165U, 130949},
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{167U, 130946},
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{171U, 130941},
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{173U, 130937},
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{177U, 130931},
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{179U, 130927},
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{183U, 130921},
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{186U, 130917},
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{189U, 130911},
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{192U, 130906},
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{196U, 130899},
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{199U, 130894},
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{203U, 130887},
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{206U, 130881},
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{210U, 130873},
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{218U, 130859},
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{225U, 130844},
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{229U, 130837},
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{233U, 130827},
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{241U, 130810},
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{250U, 130791},
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{254U, 130783}};
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const uint8_t CTCSS_TABLE_DATA_LEN = 50U;
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// 4Hz bandwidth
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const uint16_t N = 24000U / 4U;
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CFMCTCSSRX::CFMCTCSSRX() :
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m_coeff(0),
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m_threshold(0U),
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m_count(0U),
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m_q0(0),
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m_q1(0),
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m_result(false)
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{
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}
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uint8_t CFMCTCSSRX::setParams(uint8_t frequency, uint8_t threshold)
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{
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for (uint8_t i = 0U; i < CTCSS_TABLE_DATA_LEN; i++) {
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if (CTCSS_TABLE_DATA[i].frequency == frequency) {
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m_coeff = CTCSS_TABLE_DATA[i].coeff;
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break;
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}
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}
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if (m_coeff == 0)
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return 4U;
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m_threshold = threshold * threshold;
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return 0U;
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}
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bool CFMCTCSSRX::process(const q15_t* samples, uint8_t length)
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{
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for (unsigned int i = 0U; i < length; i++) {
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q31_t q2 = m_q1;
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m_q1 = m_q0;
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// Q31 multiplication, t2 = m_coeff * m_q1
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q63_t t1 = m_coeff * m_q1;
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q31_t t2 = __SSAT(t1 >> 32, 31);
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// m_q0 = m_coeff * m_q1 - q2 + samples[i]
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m_q0 = t2 - q2 + samples[i];
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m_count++;
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if (m_count == N) {
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// Q31 multiplication, t2 = m_q0 * m_q0
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q63_t t1 = m_q0 * m_q0;
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q31_t t2 = __SSAT(t1 >> 32, 31);
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// Q31 multiplication, t4 = m_q0 * m_q0
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q63_t t3 = m_q1 * m_q1;
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q31_t t4 = __SSAT(t3 >> 32, 31);
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// Q31 multiplication, t8 = m_q0 * m_q1 * m_coeff
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q63_t t5 = m_q0 * m_q1;
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q31_t t6 = __SSAT(t5 >> 32, 31);
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q63_t t7 = t6 * m_coeff;
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q31_t t8 = __SSAT(t7 >> 32, 31);
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// value = m_q0 * m_q0 + m_q1 * m_q1 - m_q0 * m_q1 * m_coeff
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q31_t value = t2 + t4 - t8;
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m_result = value >= m_threshold;
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m_count = 0U;
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m_q0 = 0;
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m_q1 = 0;
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}
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}
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return m_result;
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}
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void CFMCTCSSRX::reset()
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{
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m_q0 = 0;
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m_q1 = 0;
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m_result = false;
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m_count = 0U;
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}
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