News for hackers. Stuff that matters.

A comment on One does not simply calculate the absolute value. Parent comment

Re:One does not simply calculate the absolute value by na85 on Sunday August 22, 2021 @11:24PM (#28272029)
>Bit twiddling integers doesn't require unsafe type punning like this.

Not only that but, at least for Fast Inverse Square Root, it's not advantageous to carry out the bit twiddling since the rsqrtss instruction is faster and more precise, and vectorized instructions are faster still for large strings of floats.

[ Parent | on HN ]
Re:One does not simply calculate the absolute value by dr_zoidberg on Monday August 23, 2021 @09:34PM (#28284189)
Back when that code was used (in Quake 3, and before, a for a bit after it), there was no rsqrtss instruction.
[ Parent | on HN ]