Branch data     Line data    Source code

       1                 :             : #include <stddef.h>
       2                 :             : #include <stdint.h>
       3                 :             : 
       4                 :             : #include "common.h"
       5                 :             : #include "low_pass_filter.h"
       6                 :             : 
       7                 :             : /**
       8                 :             :  * @brief Initializes the low-pass filter by calculating and storing the alpha value
       9                 :             :  *
      10                 :             :  * This function calculates the alpha value based on the given response time and stores
      11                 :             :  * it in the provided pointer. The alpha value is used in subsequent filter updates.
      12                 :             :  *
      13                 :             :  * @param alpha Pointer to store the calculated alpha value
      14                 :             :  * @param response_time Response time constant in milliseconds (must be > 0)
      15                 :             :  * @return w_status_t Returns W_SUCCESS on success, W_INVALID_PARAM if alpha is NULL or
      16                 :             :  * response_time is invalid
      17                 :             :  */
      18                 :           4 : w_status_t low_pass_filter_init(double *alpha, double response_time) {
      19   [ +  +  +  + ]:           4 :         if (alpha == NULL || response_time <= 0) {
      20                 :             :                 return W_INVALID_PARAM; // Return specific error for invalid parameters
      21                 :             :         }
      22                 :             :         // Calculate and store the alpha value using the low_pass_alpha function
      23                 :           1 :         *alpha = low_pass_alpha(response_time, response_time);
      24                 :           1 :         return W_SUCCESS; // Return success after initialization
      25                 :             : }
      26                 :             : 
      27                 :             : /**
      28                 :             :  * @brief Updates the low-pass filter with a new value and returns the operation status
      29                 :             :  *
      30                 :             :  * This function applies the low-pass filter algorithm to the new input value using the
      31                 :             :  * provided alpha value. The filtered result is stored in low_pass_value and updated
      32                 :             :  * in-place for the next iteration.
      33                 :             :  *
      34                 :             :  * @param alpha Alpha value (0.0 to 1.0) for the low-pass filter
      35                 :             :  * @param new_input_value New input value to filter
      36                 :             :  * @param low_pass_value Pointer to the current filtered value (updated in-place)
      37                 :             :  * @return w_status_t Returns W_SUCCESS on success, W_INVALID_PARAM if low_pass_value is
      38                 :             :  * NULL or alpha is out of valid range (0.0 to 1.0)
      39                 :             :  */
      40                 :          53 : w_status_t update_low_pass(double alpha, uint16_t new_input_value, double *low_pass_value) {
      41                 :             :         // Check if low_pass_value pointer is NULL
      42         [ +  + ]:          53 :         if (low_pass_value == NULL) {
      43                 :             :                 return W_INVALID_PARAM; // Return specific error for invalid parameters
      44                 :             :         }
      45                 :             : 
      46                 :             :         // Ensure alpha is within the valid range
      47   [ +  +  +  + ]:          52 :         if (alpha <= 0.0 || alpha >= 1.0) {
      48                 :             :                 return W_INVALID_PARAM;
      49                 :             :         }
      50                 :             : 
      51                 :             :         // Low pass filter formula: y[n] = alpha * x[n] + (1 - alpha) * y[n-1]
      52                 :          50 :         *low_pass_value = (alpha * new_input_value) + ((1.0 - alpha) * (*low_pass_value));
      53                 :          50 :         return W_SUCCESS; // Return success after successful update
      54                 :             : }