calibration.h

/*
 * Copyright (c) 2023 Ruslan V. Uss <unclerus@gmail.com>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 3. Neither the name of the copyright holder nor the names of itscontributors
 *    may be used to endorse or promote products derived from this software without
 *    specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/**
 * @file calibration.h
 * @defgroup calibration calibration
 * @{
 *
 * ESP-IDF Multi-point calibration (approximation) library
 *
 * Copyright (c) 2023 Ruslan V. Uss <unclerus@gmail.com>
 *
 * BSD Licensed as described in the file LICENSE
 */
#ifndef __CALIBRATION_H__
#define __CALIBRATION_H__

#include <esp_err.h>

#ifdef __cplusplus
extern "C" {
#endif

/**
 * Approximation methods
 */
typedef enum
{
    CALIBRATION_LINEAR = 0, //!< Fast linear approximation. The more points, the more accurate approximation
} calibration_method_t;

/**
 * Calibration point
 */
typedef struct
{
    float code;   //!< Raw value
    float value;  //!< Calibrated value
} calibration_point_t;

/**
 * Calibration handler
 */
typedef struct
{
    calibration_method_t type;   //!< Approximation method
    calibration_point_t *points; //!< Ordered list of calibration points
    size_t count;                //!< Maximum number of calibration points
    size_t filled;               //!< Current number of calibration points
} calibration_handle_t;

/**
 * @brief Init calibration handle
 *
 * Allocates memory to store calibration points, fills handle structure.
 *
 * @param handler Pointer to calibration handle structure
 * @param count   Maximum number of calibration points
 * @param type    Approximation type
 *
 * @return `ESP_OK` on success
 */
esp_err_t calibration_init(calibration_handle_t *handler, size_t count, calibration_method_t type);

/**
 * @brief Add calibration point
 *
 * @param handler Pointer to calibration handle structure
 * @param code    Raw value
 * @param value   Calibrated value
 *
 * @return `ESP_OK` on success
 */
esp_err_t calibration_add_point(calibration_handle_t *handler, float code, float value);

/**
 * @brief Add multiple calibration points
 *
 * @param handler Pointer to calibration handle structure
 * @param points  Array of calibration points
 * @param count   Number of calibration points to add
 *
 * @return `ESP_OK` on success
 */
esp_err_t calibration_add_points(calibration_handle_t *handler, const calibration_point_t *points, size_t count);

/**
 * @brief Get calibrated value by raw value
 *
 * @param handler    Pointer to calibration handle structure
 * @param code       Raw value
 * @param[out] value Calculated calibrated value
 *
 * @return `ESP_OK` on success
 */
esp_err_t calibration_get_value(calibration_handle_t *handler, float code, float *value);

/**
 * @brief Free calibration handle
 *
 * @param handler Pointer to calibration handle structure
 *
 * @return `ESP_OK` on success
 */
esp_err_t calibration_free(calibration_handle_t *handler);

#ifdef __cplusplus
}
#endif

/**@}*/

#endif /* __CALIBRATION_H__ */