1
0
mirror of https://github.com/TomHarte/CLK.git synced 2024-12-25 03:32:01 +00:00
CLK/SignalProcessing/Stepper.hpp
2024-01-16 23:34:46 -05:00

96 lines
2.4 KiB
C++

//
// Stepper.hpp
// Clock Signal
//
// Created by Thomas Harte on 12/01/2016.
// Copyright 2016 Thomas Harte. All rights reserved.
//
#pragma once
#include <cstdint>
namespace SignalProcessing {
/*!
Allows a repeating action running at an input rate to determine how many times it should
trigger an action that runs at an unrelated output rate; therefore it allows something with one
clock to sample something with another.
Uses a Bresenham-like error term internally for full-integral storage with no drift.
Pegs the beginning of both clocks to the time at which the stepper is created. So e.g. a stepper
that converts from an input clock of 1200 to an output clock of 2 will first fire on cycle 600.
*/
class Stepper {
public:
/*!
Establishes a stepper with a one-to-one conversion rate.
*/
Stepper() : Stepper(1,1) {}
/*!
Establishes a stepper that will receive steps at the @c input_rate and dictate the number
of steps that should be taken at the @c output_rate.
*/
Stepper(uint64_t output_rate, uint64_t input_rate) :
accumulated_error_(-(int64_t(input_rate) << 1)),
input_rate_(input_rate),
output_rate_(output_rate),
whole_step_(output_rate / input_rate),
adjustment_up_(int64_t(output_rate % input_rate) << 1),
adjustment_down_(int64_t(input_rate) << 1) {}
/*!
Advances one step at the input rate.
@returns the number of output steps.
*/
inline uint64_t step() {
uint64_t update = whole_step_;
accumulated_error_ += adjustment_up_;
if(accumulated_error_ > 0) {
update++;
accumulated_error_ -= adjustment_down_;
}
return update;
}
/*!
Advances by @c number_of_steps steps at the input rate.
@returns the number of output steps.
*/
inline uint64_t step(uint64_t number_of_steps) {
uint64_t update = whole_step_ * number_of_steps;
accumulated_error_ += adjustment_up_ * int64_t(number_of_steps);
if(accumulated_error_ > 0) {
update += 1 + uint64_t(accumulated_error_ / adjustment_down_);
accumulated_error_ = (accumulated_error_ % adjustment_down_) - adjustment_down_;
}
return update;
}
/*!
@returns the output rate.
*/
inline uint64_t get_output_rate() {
return output_rate_;
}
/*!
@returns the input rate.
*/
inline uint64_t get_input_rate() {
return input_rate_;
}
private:
int64_t accumulated_error_;
uint64_t input_rate_, output_rate_;
uint64_t whole_step_;
int64_t adjustment_up_, adjustment_down_;
};
}