[Freeciv-Dev] Re: the directional system

[Greg Wooledge <greg@xxxxxxxxxxxx>]

Raimar Falke (hawk@xxxxxxxxxxxxxxxxxxxxxxx) wrote:
> On Fri, Sep 07, 2001 at 04:51:36AM -0700, Trent Piepho wrote:
> > +#define DIR_REVERSE(dir) (((dir) + 4) % 8)
> > +#define DIR_REVERSE(dir) (((dir) + 4) & 7)

> $ gcc -S -O2 a.c
> $ cat a.s

Nice demonstration, but it only shows that your version of gcc can handle
this optimization -- there may be other compilers out there that don't.
It's safer to use the bitwise AND operation.

-- 
Greg Wooledge                  |   "Truth belongs to everybody."
greg@xxxxxxxxxxxx              |    - The Red Hot Chili Peppers
http://wooledge.org/~greg/     |

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