mirror of https://github.com/g4klx/MMDVM.git
89 lines
1.9 KiB
C++
89 lines
1.9 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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#if defined(MODE_FM)
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#include "Globals.h"
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#include "FMBlanking.h"
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// 2000 Hz sine wave at 24000 Hz sample rate
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const q31_t TONE[] = {0, 16384, 28378, 32767, 28378, 16384, 0, -16383, -28377, -32767, -28377, -16383};
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const uint8_t TONE_LEN = 12U;
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const uint32_t BLEEP_LEN = 2400U; // 100ms
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CFMBlanking::CFMBlanking() :
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m_posValue(0),
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m_negValue(0),
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m_level(128 * 128),
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m_running(false),
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m_pos(0U),
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m_n(0U)
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{
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}
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void CFMBlanking::setParams(uint8_t value, uint8_t level)
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{
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m_posValue = q15_t(value * 128);
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m_negValue = -m_posValue;
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m_level = q15_t(level * 128);
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}
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q15_t CFMBlanking::process(q15_t sample)
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{
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if (m_posValue == 0)
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return sample;
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if (!m_running) {
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if (sample >= m_posValue) {
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m_running = true;
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m_pos = 0U;
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m_n = 0U;
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} else if (sample <= m_negValue) {
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m_running = true;
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m_pos = 0U;
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m_n = 0U;
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}
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}
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if (!m_running)
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return sample;
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if (m_pos <= BLEEP_LEN) {
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q31_t value = TONE[m_n++] * m_level;
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sample = q15_t(__SSAT((value >> 15), 16));
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if (m_n >= TONE_LEN)
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m_n = 0U;
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} else {
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sample = 0;
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}
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m_pos++;
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if (m_pos >= 12000U)
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m_running = false;
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return sample;
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}
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#endif
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