OpenGL Mathematics (GLM)
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/*
inline __m128 _mm_rsqrt_nr_ss(__m128 const x)
{
__m128 recip = _mm_rsqrt_ss( x ); // "estimate" opcode
const static __m128 three = { 3, 3, 3, 3 }; // aligned consts for fast load
const static __m128 half = { 0.5,0.5,0.5,0.5 };
__m128 halfrecip = _mm_mul_ss( half, recip );
__m128 threeminus_xrr = _mm_sub_ss( three, _mm_mul_ss( x, _mm_mul_ss ( recip, recip ) ) );
return _mm_mul_ss( halfrecip, threeminus_xrr );
}
inline __m128 __mm_normalize_fast_ps( float * RESTRICT vOut, float * RESTRICT vIn )
{
__m128 x = _mm_load_ss(&vIn[0]);
__m128 y = _mm_load_ss(&vIn[1]);
__m128 z = _mm_load_ss(&vIn[2]);
const __m128 l = // compute x*x + y*y + z*z
_mm_add_ss(
_mm_add_ss( _mm_mul_ss(x,x),
_mm_mul_ss(y,y)
),
_mm_mul_ss( z, z )
);
const __m128 rsqt = _mm_rsqrt_nr_ss( l );
_mm_store_ss( &vOut[0] , _mm_mul_ss( rsqt, x ) );
_mm_store_ss( &vOut[1] , _mm_mul_ss( rsqt, y ) );
_mm_store_ss( &vOut[2] , _mm_mul_ss( rsqt, z ) );
return _mm_mul_ss( l , rsqt );
}
*/