mirror of
https://github.com/eried/portapack-mayhem.git
synced 2024-10-01 01:26:06 -04:00
94 lines
2.5 KiB
C++
94 lines
2.5 KiB
C++
/*
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* Copyright (C) 2014 Jared Boone, ShareBrained Technology, Inc.
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*
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* This file is part of PortaPack.
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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, or (at your option)
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* 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; see the file COPYING. If not, write to
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* the Free Software Foundation, Inc., 51 Franklin Street,
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* Boston, MA 02110-1301, USA.
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*/
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#ifndef __CLOCK_RECOVERY_H__
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#define __CLOCK_RECOVERY_H__
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#include <cstdint>
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class ClockRecovery {
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public:
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void configure(
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const uint32_t symbol_rate,
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const uint32_t sampling_rate
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);
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template<typename SymbolHandler>
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void execute(
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const float in,
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SymbolHandler symbol_handler
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) {
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const bool phase_0 = (phase_last >> 31) & (!(phase >> 31));
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const bool phase_180 = (!(phase_last >> 31)) & (phase >> 31);
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if( phase_0 || phase_180 ) {
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t2 = t1;
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t1 = t0;
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const uint32_t phase_boundary = phase_180 ? (1U << 31) : 0;
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const float alpha = (phase_boundary - phase_last) / float(phase_increment + phase_adjustment);
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const float t = last_sample + alpha * (in - last_sample);
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t0 = t;
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}
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if( phase_0 ) {
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symbol_handler(t0);
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const float error = (t0 - t2) * t1;
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// + error == late == decrease/slow phase
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// - error == early == increase/fast phase
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error_filtered = 0.75f * error_filtered + 0.25f * error;
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// Correct phase (don't change frequency!)
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phase_adjustment = -phase_increment * error_filtered / 200.0f;
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}
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phase_last = phase;
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phase += phase_increment + phase_adjustment;
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last_sample = in;
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}
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private:
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uint32_t phase { 0 };
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uint32_t phase_last { 0 };
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uint32_t phase_adjustment { 0 };
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uint32_t phase_increment { 0 };
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float last_sample { 0 };
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float t0 { 0 };
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float t1 { 0 };
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float t2 { 0 };
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float error_filtered { 0 };
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static constexpr float fractional_symbol_rate(
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const uint32_t symbol_rate,
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const uint32_t sampling_rate
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) {
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return float(symbol_rate) / float(sampling_rate);
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}
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static constexpr uint32_t phase_increment_u32(const float fractional_symbol_rate) {
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return 4294967296.0f * fractional_symbol_rate;
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}
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};
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#endif/*__CLOCK_RECOVERY_H__*/
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