.. _program_listing_file_mainboard_Src_energy_energy.c:

Program Listing for File energy.c
=================================

|exhale_lsh| :ref:`Return to documentation for file <file_mainboard_Src_energy_energy.c>` (``mainboard/Src/energy/energy.c``)

.. |exhale_lsh| unicode:: U+021B0 .. UPWARDS ARROW WITH TIP LEFTWARDS

.. code-block:: cpp

   
   /* Includes ------------------------------------------------------------------*/
   #include "energy/energy.h"
   
   #include <stdlib.h>
   
   /* Private typedef -----------------------------------------------------------*/
   struct energy {
       uint32_t last_sample;
       float energy;
       float last_power;
   };
   
   /* Private define ------------------------------------------------------------*/
   /* Private macro -------------------------------------------------------------*/
   /* Private variables ---------------------------------------------------------*/
   /* Private function prototypes -----------------------------------------------*/
   /* Exported functions --------------------------------------------------------*/
   
   void energy_init(energy_t *handle) {
       *handle = malloc(sizeof(struct energy));
       energy_set_count(*handle, 0);
       energy_set_time(*handle, 0);
   }
   
   void energy_deinit(energy_t *handle) {
       free(*handle);
   }
   
   void energy_set_count(energy_t handle, float energy) {
       handle->energy = energy;
   }
   
   void energy_set_time(energy_t handle, uint32_t time) {
       handle->last_sample = time;
       handle->last_power  = 0;
   }
   
   void energy_sample_energy(energy_t handle, float power, uint32_t time) {
       // Use trapezoidal rule to approximate an integral
       // Energy = ∫Power dt = (1/2 * (P[i-1] + P[i])) * Δt
       handle->energy += ((handle->last_power + power) / 2) * ((time - handle->last_sample) / 1000.0f);
   
       handle->last_power  = power;
       handle->last_sample = time;
   }
   
   float energy_get_wh(energy_t handle) {
       // 1 J = 1/3600s Wh
       return handle->energy / 3600;
   }
   
   float energy_get_joule(energy_t handle) {
       return handle->energy;
   }