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

extern float inverse_sqrt(float);
extern float inverse_sqrt(float);
extern int square_of_greater(int, int);

float Q_rsqrt(float number)
{
  long i;
  float x2, y;
  const float threehalfs = 1.5F;

  x2 = number * 0.5F;
  y  = number;
  i  = * ( long * ) &y;                       // evil floating point bit level hacking
  i  = 0x5f3759df - ( i >> 1 );               // what the fuck?
  y  = * ( float * ) &i;
  y  = y * ( threehalfs - ( x2 * y * y ) );   // 1st iteration
  // y  = y * ( threehalfs - ( x2 * y * y ) );   // 2nd iteration, this can be removed

  return y;
}

int main() {
  printf("hello, world!\n");
  float n = 4.0;
  float i = inverse_sqrt(n);
  printf("%f = inverse_sqrt(%f)\n", i, n);
  printf("%f = Q_rsqrt(%f)\n", Q_rsqrt(4.0), 4.0);
  printf("%d = square_of_greater(4,5)\n", square_of_greater(4, 5));
  return 0;
}