data.c

#include <string.h> // memset
#include <stdlib.h> // malloc, free

#include "data.h"

float find_max(values_t *values) {
  // Find max value in values_t
  int i = 0;
  float max = -1;
  for(i = 0; i < values->size; i++) {
    if(values->values[i] > max)
      max = values->values[i];
  }

  return max;
}


void init_values(values_t *values, int history_size) {
  values->values = malloc(history_size*sizeof(float));
  memset(values->values, 0, history_size*sizeof(float));
  values->max = 0;
  values->global_max = 0;
  values->size = history_size;
  values->i = 0;
}

void resize_values(values_t *values, int history_size) {
  // Do not resize down, save history in case of resize up later
  // Exit if history_size is less than 0
  if(history_size < 0 || history_size < values->size)
    return;

  float *old_values = values->values;
  int old_size = values->size;
  int old_i = values->i;

  // Initialize new values with new history size
  init_values(values, history_size);

  // Add values from old in order as before
  int i = 0;
  for(i = 0; i < old_size; i++)
    add_value(values, old_values[((i+old_i) % old_size)]);

  free(old_values);
}

void add_value(values_t *values, float v) {
  // Add new value to values_t
  values->values[values->i] = v;
  values->i += 1;
  values->i %= values->size;
  float new_max = find_max(values);
  values->max = new_max;
  if(new_max > values->global_max)
    values->global_max = new_max;
}

float previous_value(values_t *values) {
  // Return value at index i-1 (with wrapping)
  int i = (values->i + values->size -1) % values->size;
  return values->values[i];
}

void dealloc_values(values_t *values) {
  free(values->values);
  values->values = NULL;
}