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/* Copyright 2020 The Chromium OS Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef __CROS_EC_GYRO_STILL_DET_H
#define __CROS_EC_GYRO_STILL_DET_H
#include "common.h"
#include "math_util.h"
#include "stdbool.h"
#include "vec3.h"
struct gyro_still_det {
/**
* Variance threshold for the stillness confidence score.
* [sensor units]^2
*/
fp_t var_threshold;
/**
* Delta about the variance threshold for calculation of the stillness
* confidence score [0,1]. [sensor units]^2
*/
fp_t confidence_delta;
/**
* Flag to indicate when enough samples have been collected for
* a complete stillness calculation.
*/
bool stillness_window_ready;
/**
* Flag to signal the beginning of a new stillness detection window.
* This is used to keep track of the window start time.
*/
bool start_new_window;
/** Starting time stamp for the current window. */
uint32_t window_start_time;
/**
* Accumulator variables for tracking the sample mean during
* the stillness period.
*/
uint32_t num_acc_samples;
fpv3_t mean;
/**
* Accumulator variables for computing the window sample mean and
* variance for the current window (used for stillness detection).
*/
uint32_t num_acc_win_samples;
fpv3_t win_mean;
fpv3_t assumed_mean;
fpv3_t acc_var;
/** Stillness period mean (used for look-ahead). */
fpv3_t prev_mean;
/** Latest computed variance. */
fpv3_t win_var;
/**
* Stillness confidence score for current and previous sample
* windows [0,1] (used for look-ahead).
*/
fp_t stillness_confidence;
fp_t prev_stillness_confidence;
/** Timestamp of last sample recorded. */
uint32_t last_sample_time;
};
/** Update the stillness detector with a new sample. */
void gyro_still_det_update(struct gyro_still_det *gyro_still_det,
uint32_t stillness_win_endtime, uint32_t sample_time,
fp_t x, fp_t y, fp_t z);
/** Calculates and returns the stillness confidence score [0,1]. */
fp_t gyro_still_det_compute(struct gyro_still_det *gyro_still_det);
/**
* Resets the stillness detector and initiates a new detection window.
*
* @param reset_stats Determines whether the stillness statistics are reset.
*/
void gyro_still_det_reset(struct gyro_still_det *gyro_still_det,
bool reset_stats);
#endif /* __CROS_EC_GYRO_STILL_DET_H */
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