#include <stdio.h>
#include <unistd.h>

static void *addr = (void *)0x2000000;

/**
 * Tries to allocate a block of memory including address 0x2000000.
 * On success, returns a pointer to the beginning of that block.
 * On failure, returns NULL.
 */
void *allocateToAddr() {
    void *heapBase = sbrk(0);
    if (heapBase > addr) {
        fprintf(stderr, "Heap started at %p > %p\n", heapBase, addr);
        return NULL;
    }
    void *block = sbrk((addr-heapBase)+8);
    return block;
}

int main(int argc, char *argv[]) {
    void *p = allocateToAddr();
    if (!p) return 1;
    char *c = addr;
    *c = 0;
    for(int i=0; i<10; i+=1) {
        *c += 1;
        printf("Address %p, value = %hhd\n", c, *c);
        sleep(2);
    }
    return 0;
}