mirror of
https://github.com/TomHarte/CLK.git
synced 2024-07-07 23:29:06 +00:00
75 lines
2.6 KiB
C++
75 lines
2.6 KiB
C++
//
|
|
// DigitalPhaseLockedLoop.cpp
|
|
// Clock Signal
|
|
//
|
|
// Created by Thomas Harte on 11/07/2016.
|
|
// Copyright © 2016 Thomas Harte. All rights reserved.
|
|
//
|
|
|
|
#include "DigitalPhaseLockedLoop.hpp"
|
|
|
|
using namespace Storage;
|
|
|
|
DigitalPhaseLockedLoop::DigitalPhaseLockedLoop(unsigned int clocks_per_bit, unsigned int tolerance, unsigned int length_of_history) :
|
|
_clocks_per_bit(clocks_per_bit),
|
|
_tolerance(tolerance),
|
|
_length_of_history(length_of_history),
|
|
_pulse_history(new unsigned int[length_of_history]),
|
|
_current_window_length(clocks_per_bit),
|
|
_next_pulse_time(0),
|
|
_window_was_filled(false),
|
|
_window_offset(0) {}
|
|
|
|
void DigitalPhaseLockedLoop::run_for_cycles(unsigned int number_of_cycles)
|
|
{
|
|
// check whether this triggers any 0s
|
|
_window_offset += number_of_cycles;
|
|
if(_delegate)
|
|
{
|
|
while(_window_offset > _current_window_length)
|
|
{
|
|
if(!_window_was_filled) _delegate->digital_phase_locked_loop_output_bit(0);
|
|
_window_was_filled = false;
|
|
_window_offset -= _current_window_length;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
_window_offset %= _current_window_length;
|
|
}
|
|
|
|
// update timing
|
|
_next_pulse_time += number_of_cycles;
|
|
}
|
|
|
|
void DigitalPhaseLockedLoop::add_pulse()
|
|
{
|
|
unsigned int *const _pulse_history_array = _pulse_history.get();
|
|
|
|
// attempt a phase correction by means of adjusting the window length
|
|
int total_offset = 0;
|
|
for(size_t pulse = 0; pulse < _length_of_history; pulse++)
|
|
{
|
|
total_offset += _pulse_history_array[pulse] % _current_window_length;
|
|
}
|
|
_current_window_length += (unsigned int)(((total_offset - (int)(_length_of_history*_current_window_length >> 1)) >> 2) / (int)_length_of_history);
|
|
if(_current_window_length < _clocks_per_bit - _tolerance) _current_window_length = _clocks_per_bit - _tolerance;
|
|
if(_current_window_length > _clocks_per_bit + _tolerance) _current_window_length = _clocks_per_bit + _tolerance;
|
|
printf("Total across %d samples is %d; adjusted length to %d\n", _length_of_history, total_offset, _current_window_length);
|
|
|
|
// therefore, there was a 1 in this window
|
|
_window_was_filled = true;
|
|
if(_delegate) _delegate->digital_phase_locked_loop_output_bit(1);
|
|
|
|
// shift history one to the left, storing new value; act as though the outgoing pulse were exactly halfway through its
|
|
// window for adjustment purposes
|
|
unsigned int outgoing_pulse_time = _pulse_history_array[0] + (_current_window_length >> 1);
|
|
|
|
for(size_t pulse = 1; pulse < _length_of_history; pulse++)
|
|
{
|
|
_pulse_history_array[pulse - 1] = _pulse_history_array[pulse] - outgoing_pulse_time;
|
|
}
|
|
_next_pulse_time -= outgoing_pulse_time;
|
|
_pulse_history_array[_length_of_history-1] = _next_pulse_time;
|
|
}
|