#include <stdint.h>
#include <sys/mman.h>
#include <limits.h>    /* for PAGESIZE */
#ifndef PAGESIZE
#define PAGESIZE 4096
#endif

int main(int ac,char** av) {
  __label__ FOO;
  uint8_t* code;
  uint8_t* p;
  register int a;
  register int b;
  int n,m;

  if (ac<2) {
    printf("supply a number between 0 and 5\n");
    exit(1);
  }
  m = n = atoi(av[1]);
  if (m < 0 || m > 5) {
    printf("supply a number between 0 and 5\n");
    exit(1);
  }
  printf("n: %d\n",n);

  code=&&FOO;

  p = (uint8_t*)&main - PAGESIZE;
  p = (char *)(((int) p + PAGESIZE-1) & ~(PAGESIZE-1));

  if (mprotect(p, PAGESIZE*2, PROT_READ|PROT_WRITE|PROT_EXEC)) {
    perror("Couldn't mprotect");
    exit(1);
  }

  code++;
  *((uint32_t*)code) = 63245986; // 39
  code+=5;
  *((uint32_t*)code) = 102334155; // 40
  code+=14;
  while (n--) {
    *(--code)=0x90;
    *(--code)=0x90;
  }

FOO:
  a = 0;
  b = 0;
  a += b; // 41
  b += a; // 42
  a += b; // 43
  b += a; // 44
  a += b; // 45
  b += a; // 46

  printf("fib %d: %u\n", (46-m), b);

  return 0;
}