small question about isdn-code

Dag Wieers (dag@life.be)
Sat, 6 Mar 1999 17:09:00 +0100 (CET)

while trying to solve a problem for a friend, i came across the following
code:

if ((card->typ > 0) && (card->typ < 31)) {
if (!((1 << card->typ) & SUPORTED_CARDS)) {
printk(KERN_WARNING
"HiSax: Support for %s Card not selected\n",
CardType[card->typ]);
restore_flags(flags);
return (0);
}
} else {
...

why do they do:
(1 << card->typ)

if they already checked if card->typ is between 0 and 31 ?

(i think i'm missing something here ;))

--
dag wieers, <dag@life.be>, http://dag.life.be/  _| _  _
for life is quite absurd,                      (_|(_|(_|
   and death's the final word. -- Monty Python         |




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