Messages in this thread | | | Subject | Re: [OFFTOPIC?] Re: 2.2.x kernels missend odd-sized ICMP pa | Date | Mon, 12 Apr 1999 07:31:28 -0400 | From | Horst von Brand <> |
| |
Vojtech Pavlik <vojtech-lists@twilight.ucw.cz> said: > On Sun, Apr 11, 1999 at 09:51:35PM -0400, Horst von Brand wrote: > > (This is an excerpt from ping.c:in_cksum in netkit-0.10, sent to me by Petr > > Vandrovec):
> > register u_short *w = addr; > > register int sum = 0; > > u_short answer = 0; > > .... > > *(u_char*)(&answer) = *(u_char*)w; > > sum += answer;
> > This is a dumb way to write this. > > > > egcs-19990405 generates code that gets the right value, others (including > > egcs-1.0.3 used to build RedHat-5.2, AFAIKS) break, as they don't respect > > the initialization and put a random byte in the higher half. > > > > A better way to write the above is just: > > > > sum += *(u_char*)w;
> But, isn't this a compiler bug anyway? It shouldn't ignore the initialization > in this case - actually I wonder why it would decide to.
Yes, it is a genuine compiler bug. One that can be worked around by writing cleaner code, in this particular case ;-) -- Horst von Brand vonbrand@sleipnir.valparaiso.cl Casilla 9G, Viña del Mar, Chile +56 32 672616
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/
| |