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Started sketching out the basic form here, albeit that it doesn't yet do _the only thing it advertises itself as useful for_.

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This commit is contained in:
Thomas Harte 2016-07-12 20:23:56 -04:00
parent 75d95c0bc0
commit 94db45456e
2 changed files with 70 additions and 1 deletions
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55
Storage/Disk/DigitalPhaseLockedLoop.cpp
View File

@ -7,3 +7,58 @@
//
#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;
}
// updte timing
_next_pulse_time += number_of_cycles;
}
void DigitalPhaseLockedLoop::add_pulse()
{
// TODO: linear regression to adjust _current_window_length and _next_pulse_time
// 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, subtracting the outgoing pulse from
unsigned int *const _pulse_history_array = _pulse_history.get();
unsigned int outgoing_pulse_time = _pulse_history_array[0];
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;
}

16
Storage/Disk/DigitalPhaseLockedLoop.hpp
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@ -9,6 +9,8 @@
#ifndef DigitalPhaseLockedLoop_hpp
#define DigitalPhaseLockedLoop_hpp
#include <memory>
namespace Storage {
class DigitalPhaseLockedLoop {
@ -18,8 +20,9 @@ class DigitalPhaseLockedLoop {
@param clocks_per_bit The expected number of cycles between each bit of input.
@param tolerance The maximum tolerance for bit windows — extremes will be clocks_per_bit ± tolerance.
@param length_of_history The number of historic pulses to consider in locking to phase.
*/
DigitalPhaseLockedLoop(unsigned int clocks_per_bit, unsigned int tolerance);
DigitalPhaseLockedLoop(unsigned int clocks_per_bit, unsigned int tolerance, unsigned int length_of_history);
/*!
Runs the loop, impliedly posting no pulses during that period.
@ -47,6 +50,17 @@ class DigitalPhaseLockedLoop {
private:
Delegate *_delegate;
std::unique_ptr<unsigned int> _pulse_history;
unsigned int _current_window_length;
unsigned int _length_of_history;
unsigned int _next_pulse_time;
unsigned int _window_offset;
bool _window_was_filled;
unsigned int _clocks_per_bit;
unsigned int _tolerance;
};
}