[Freeciv-Dev] Re: [Patch] Small patch

[Raimar Falke <hawk@xxxxxxxxxxxxxxxxxxxxxxx>]

On Sun, Feb 10, 2002 at 06:49:10PM +0000, Gregory Berkolaiko wrote:
>  --- Raimar Falke <hawk@xxxxxxxxxxxxxxxxxxxxxxx> wrote: 
> 
> [...]
> >        \
> >    int ARG_x_itr, ARG_y_itr;                                           
> >        \
> >    int MACRO_max_dx = map.xsize/2;                                     
> >        \
> > -  int MACRO_min_dx = -(MACRO_max_dx - (map.xsize%2 ? 0 : 1));         
> >        \
> > +  int MACRO_min_dx = -MACRO_max_dx - 1 + (map.xsize % 2);             
> 
> performance issue: are you sure (map.xsize%2 ? 0 : 1) gets optimized?

No it doesn't. As I said: we can remove one jump.

> or maybe we can write (map.xsize & 1) to make sure about it?

signed int x;
unsigned int y;

"x%2" is

        movl    %edx, %eax
        shrl    $31, %eax
        leal    (%eax,%edx), %eax
        andl    $-2, %eax
        subl    %eax, %edx

while "y%2", "x&1" and "y&1" is

        andl    $1, %eax

So yes this may be optimized further.

        Raimar

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