Demonstration of malloc failure with 4KB heap left

malloctest.c

#include <stdio.h>
#include <stdlib.h>
#include "pico/stdlib.h"

uint32_t use_almost_all_memory[63410];

int main()
{
    stdio_init_all();

    // Reference the big array so it isn't removed by the linker
    use_almost_all_memory[0] = 1;

    int i = 0;
    while (1) {
      void* ptr = malloc(36);
      if (!ptr) break;
      printf("Allocated pointer %p\n", ptr);
      ++i;
    }

    printf("Failed after %d allocations of 36 bytes\n", i);

    return 0;
}