[XviD-devel] Re: Quality optimization

[Christoph Lampert]

On Sat, 25 Jan 2003, Felix von Leitner wrote:
> Here is a small piece of code for your consideration:
> 
>   static inline int abs(int x) { return x<0?-x:x; }
> 
>   static inline int newabs(int x) {
>     return (((x>>(sizeof(int)*8-1)) & (x^(-x))) ^ x);
>   }
> 
> newabs calculates the absolute of a signed integer without branches.
> 
> ...
> The good thing about this algorithm is that it can be done in parallel
> using MMX, so we can theoretically do abs(X) and abs(Y) simultaneously.

Since MMX can subtract with saturation, calcuting several abs with MMX
is very 
simple and fast already. 

gruel