Created
August 4, 2018 05:39
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Qsqrt
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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 | |
#ifndef Q3_VM # | |
ifdef __linux__ assert( !isnan(y) ); // bk010122 - FPE? | |
#endif | |
#endif return y; | |
} |
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