Subject:
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Re: random() compile problems
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Newsgroups:
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lugnet.robotics.rcx.legos
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Date:
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Tue, 21 Dec 1999 11:59:10 GMT
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Viewed:
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1486 times
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Martin Cornelius wrote:
> Hi Matthew, it lokks like the functions are simply not defined neither
> in the legOS kernel nor in the libs. Following the comment in
> include/stdlib.h, they should be in libiberty.a, which is somewhere in
> the cross-compiler tree. However, searching through the librarys found
Yes, it looks like random is in a private library of mine, sorry. With
all the exciting networking development happening, count on 0.2.4 being
released soon, it will contain random() again.
> there with nm, i found nothing like random. i´d bet, Markus has an
> enhanced libiberty that has it. BTW, the legOS kernel itself uses
> sys_time to provide some randomness, look at the very end of
> lnp_logical_write(), where a random value is needed when computing
> allow_tx after a collision.
For small amounts of random numbers, you may consider using a generator
like this:
#define PRIME1 402653189
#define PRIME2 201326611
static unsigned long random_pool;
void random_init() {
random_pool=sys_time;
}
unsigned long random() {
unsigned long random_value=PRIME1*random_pool;
random_pool=PRIME2*(random_pool+sys_time);
return random_value;
}
where PRIME1 and PRIME2 are suitably large prime numbers (for looks.
Actually, large odd numbers suffice).
Note this doesn't generate a repeatable sequence of random numbers,
because sys_time is used in random(), too.
Markus.
--
"Nieder mit den Zitaten!" -Markus L. Noga <markus@noga.de>
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Message is in Reply To:
 | | Re: random() compile problems
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| (...) Hi Matthew, it lokks like the functions are simply not defined neither in the legOS kernel nor in the libs. Following the comment in include/stdlib.h, they should be in libiberty.a, which is somewhere in the cross-compiler tree. However, (...) (25 years ago, 21-Dec-99, to lugnet.robotics.rcx.legos)
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