livetrax/libs/backends/portaudio/cycle_timer.h

/*
 * Copyright (C) 2015 Tim Mayberry <mojofunk@gmail.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#ifndef CYCLE_TIMER_H
#define CYCLE_TIMER_H

#include <stdint.h>
#include <cmath>
#include <algorithm>

// Could call it FrameTimer and make it more generic
// Could be an interface and or include clock source
// include sample count/processed frames in iteration?
class CycleTimer {
public:
	CycleTimer ()
	    : m_cycle_start (0)
	    , m_samplerate (0)
	    , m_samples_per_cycle (0)
	{
	}

	void set_samplerate (double samplerate) { m_samplerate = samplerate; }

	double get_samplerate () const { return m_samplerate; }

	double get_sample_length_us () const { return 1e6 / m_samplerate; }

	double get_length_us () const
	{
		return get_sample_length_us () * m_samples_per_cycle;
	}

	void set_samples_per_cycle (uint32_t samples)
	{
		m_samples_per_cycle = samples;
	}

	uint32_t get_samples_per_cycle () const { return m_samples_per_cycle; }

	// rint?? that may round to sample outside of cycle?
	// max(0, value)?
	uint32_t samples_since_cycle_start (int64_t timer_val) const
	{
		if (timer_val < m_cycle_start) {
			return 0;
		}
		return std::max((double)0, (timer_val - get_start ()) / get_sample_length_us ());
	}

	int64_t timestamp_from_sample_offset (uint32_t sample_offset)
	{
		return m_cycle_start + get_sample_length_us () * sample_offset;
	}

	bool valid () const { return m_samples_per_cycle && m_samplerate; }

	bool in_cycle(int64_t timer_value_us) const
	{
		return (timer_value_us >= get_start()) && (timer_value_us < get_next_start());
	}

	void reset_start (int64_t timestamp) { m_cycle_start = timestamp; }

	int64_t get_start () const { return m_cycle_start; }

	int64_t microseconds_since_start (int64_t timestamp) const
	{
		return timestamp - m_cycle_start;
	}

	int64_t microseconds_since_start (uint32_t samples) const
	{
		return m_cycle_start + samples * get_sample_length_us ();
	}

	int64_t get_next_start () const
	{
		return m_cycle_start + rint (get_length_us ());
	}

private:
	int64_t m_cycle_start;

	uint32_t m_samplerate;
	uint32_t m_samples_per_cycle;
};

#endif // CYCLE_TIMER_H