// Using the heap for memory allocation

#include "mem_syms.h"
#define ADDR DEC

void print_heap_stats() {
  Serial.print("Avail mem:");  Serial.println(AVAIL_MEM, DEC);
  Serial.print("Heap size:");  Serial.println(HEAP_SIZE, DEC);
  Serial.print("Heap starts at:");  Serial.println((unsigned int) HEAP_START, ADDR);
  Serial.print("Heap ends at:");  Serial.println( (unsigned int) HEAP_END, ADDR);
}

void print_array(int a[], unsigned int len) {
  Serial.print("array at ");
  Serial.print( (unsigned int) a, ADDR);
  Serial.print(" has len ");
  Serial.println(len);
  
  if ( ! a ) {
    // oops, no array
    Serial.println("Null pointer!");
    return;
  }
  
  for (int i=0; i < len; i++ ) {
    Serial.print(a[i], DEC);
    if (i < len-1) { Serial.print(","); }
  }
  Serial.println(".");
}

// create a new array of ints, of length len, and fill with 
// some data
int * make_random_array(unsigned int len) {
  Serial.println("make random array");
  int *a;
  a = (typeof(a)) malloc(sizeof(*a) * len);
  // always check the return code of malloc
  if ( a == 0 ) {
     Serial.println("No memory!");
     while ( 1 ) {}
     }

  for (int i=0; i < len; i++) {
    // note a[i] is just shorthand for *(a+i)
    // where the units of i are sizeof thing pointed to by a
    a[i] = random(0, 100);
  }
  return a;
}

void setup()
{
  Serial.begin(9600);
  
  Serial.println("MEM09 - dynamic arrays");

  unsigned int array_1_len;
  int * array_1;
  
  unsigned int array_2_len;
  int * array_2;

  unsigned int array_3_len;
  int * array_3;

  print_heap_stats();
  array_1_len = 20;
  array_1 = make_random_array(array_1_len);
  print_heap_stats();
  print_array(array_1, array_1_len);
  Serial.println("free 1");
  free(array_1);
  print_heap_stats();
  
  array_2_len = 10;
  array_2 = make_random_array(array_2_len);
  print_heap_stats();
  print_array(array_2, array_2_len);
  
  array_3_len = 10;
  array_3 = make_random_array(array_3_len);
  print_heap_stats();
  print_array(array_3, array_3_len);

  Serial.println("free 2");
  free(array_2);
  print_heap_stats();

  Serial.println("free 3");
  free(array_3);
  print_heap_stats();

}

void loop() {
}