[XviD-devel] Decoder performance

[Christoph Lampert]

On Sun, 10 Aug 2003, Edouard Gomez wrote:
> Oh,  i had  a  nicer  solution than  the  ? operator  for  that (on  the
> paper). Completely branchless.
> 
> #define IS_SET_FLAG(a, flag) \
>  (!!((a)&(flag)))

Yes, '!!' is the usual way to make an arithmetic value in to a logical
"true" or "false". 

But if I remember correctly, "true" and "false" are not necessarily equal
to 1 and 0 on all machines, they might be -1 and 0 or just anything
and 0. So !! is just helpful to compare truthness by '==', but not by
doing calculations with the result (even though it works on all compilers
I know of...)

gruel