servo.c

/**
 * @file servo.c
 * @note Copyright (C) 2011 Richard Cochran <richardcochran@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.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */
#include <string.h>
#include <stdlib.h>

#include "config.h"
#include "linreg.h"
#include "ntpshm.h"
#include "nullf.h"
#include "pi.h"
#include "servo_private.h"

#include "print.h"

#define NSEC_PER_SEC 1000000000

struct servo *servo_create(struct config *cfg, enum servo_type type,
			   int fadj, int max_ppb, int sw_ts)
{
	double servo_first_step_threshold;
	double servo_step_threshold;
	int servo_max_frequency;
	struct servo *servo;

	switch (type) {
	case CLOCK_SERVO_PI:
		servo = pi_servo_create(cfg, fadj, sw_ts);
		break;
	case CLOCK_SERVO_LINREG:
		servo = linreg_servo_create(fadj);
		break;
	case CLOCK_SERVO_NTPSHM:
		servo = ntpshm_servo_create(cfg);
		break;
	case CLOCK_SERVO_NULLF:
		servo = nullf_servo_create();
		break;
	default:
		return NULL;
	}

	if (!servo)
		return NULL;

	servo_step_threshold = config_get_double(cfg, NULL, "step_threshold");
	if (servo_step_threshold > 0.0) {
		servo->step_threshold = servo_step_threshold * NSEC_PER_SEC;
	} else {
		servo->step_threshold = 0.0;
	}

	servo_first_step_threshold =
		config_get_double(cfg, NULL, "first_step_threshold");

	if (servo_first_step_threshold > 0.0) {
		servo->first_step_threshold =
			servo_first_step_threshold * NSEC_PER_SEC;
	} else {
		servo->first_step_threshold = 0.0;
	}

	servo_max_frequency = config_get_int(cfg, NULL, "max_frequency");
	servo->max_frequency = max_ppb;
	if (servo_max_frequency && servo->max_frequency > servo_max_frequency) {
		servo->max_frequency = servo_max_frequency;
	}

	servo->first_update = 1;
	servo->offset_threshold = config_get_int(cfg, NULL, "servo_offset_threshold");
	servo->num_offset_values = config_get_int(cfg, NULL, "servo_num_offset_values");
	servo->curr_offset_values = servo->num_offset_values;

	return servo;
}

void servo_destroy(struct servo *servo)
{
	servo->destroy(servo);
}

static int check_offset_threshold(struct servo *s, int64_t offset)
{
	long long int abs_offset = llabs(offset);

	if (s->offset_threshold) {
		if (abs_offset < s->offset_threshold && s->curr_offset_values)
			s->curr_offset_values--;
		return s->curr_offset_values ? 0 : 1;
	}
	return 0;
}

double servo_sample(struct servo *servo,
		    int64_t offset,
		    uint64_t local_ts,
		    double weight,
		    enum servo_state *state)
{
	double r;

	r = servo->sample(servo, offset, local_ts, weight, state);

	switch (*state) {
	case SERVO_UNLOCKED:
		servo->curr_offset_values = servo->num_offset_values;
		break;
	case SERVO_JUMP:
		servo->curr_offset_values = servo->num_offset_values;
		servo->first_update = 0;
		break;
	case SERVO_LOCKED:
		if (check_offset_threshold(servo, offset)) {
			*state = SERVO_LOCKED_STABLE;
		}
		servo->first_update = 0;
		break;
	case SERVO_LOCKED_STABLE:
		/*
		 * This case will never occur since the only place
		 * SERVO_LOCKED_STABLE is set is in this switch/case block
		 * (case SERVO_LOCKED).
		 */
		break;
	}

	return r;
}

void servo_sync_interval(struct servo *servo, double interval)
{
	servo->sync_interval(servo, interval);
}

void servo_reset(struct servo *servo)
{
	servo->reset(servo);
}

double servo_rate_ratio(struct servo *servo)
{
	if (servo->rate_ratio)
		return servo->rate_ratio(servo);

	return 1.0;
}

void servo_leap(struct servo *servo, int leap)
{
	if (servo->leap)
		servo->leap(servo, leap);
}

int servo_offset_threshold(struct servo *servo)
{
	return servo->offset_threshold;
}