#include <stdio.h>
#include <string.h>
#include <stdint.h>
#include <stdlib.h>

unsigned int crc32a(uint8_t *message, unsigned int size);

unsigned int fib(unsigned int n)
{
    if (n == 0) {
        return 0;
    }

    unsigned int a = 0;
    unsigned int b = 1;

    for (unsigned int i = 1; i < n; i++) {
        unsigned int next = a + b;
        a = b;
        b = next;
    }

    return b;
}

void rot13(char *buf)
{
    while (*buf) {
        if ((*buf >= 'a' && *buf <= 'm') ||
                (*buf >= 'A' && *buf <= 'M')) {
            *buf += 13;
        } else if ((*buf >= 'n' && *buf <= 'z') ||
                (*buf >= 'N' && *buf <= 'Z')) {
            *buf -= 13;
        }
        buf++;
    }
}

size_t strlen(const char *buf)
{
    int len = 0;
    while (buf[len])
        len++;
    return len;
}

extern void *__malloc_freelist;

int main()
{
    __malloc_freelist = 0;

    volatile int i = 0;
    int j = 0;
    char *fox = "The quick brown fox jumps of the lazy dog.";
    unsigned int checksum = 0;
    volatile uint32_t i32 = 0xdeadbeef;
    volatile uint64_t i64 = 0x1122334455667788;

start:
    while (i)
        j++;

    rot13(fox);
    checksum ^= crc32a(fox, strlen(fox));
    rot13(fox);
    checksum ^= crc32a(fox, strlen(fox));

    return checksum;
}