Q_rsqrt

1float Q_rsqrt( float number )
2{
3	long i;
4	float x2, y;
5	const float threehalfs = 1.5F;
6
7	x2 = number * 0.5F;
8	y  = number;
9	i  = * ( long * ) &y;                       // evil floating point bit level hacking
10	i  = 0x5f3759df - ( i >> 1 );               // what the fuck? 
11	y  = * ( float * ) &i;
12	y  = y * ( threehalfs - ( x2 * y * y ) );   // 1st iteration
13//	y  = y * ( threehalfs - ( x2 * y * y ) );   // 2nd iteration, this can be removed
14
15	return y;
16}