Revision 5ced1339612d1fa095459bd481f1d1f64f76f859 authored by Linus Lüssing on 15 February 2011, 13:19:20 UTC, committed by David S. Miller on 22 February 2011, 18:07:27 UTC
This commit adds the missing IPv6 multicast address flag defines to
complement the already existing multicast address scope defines and to
be able to check these flags nicely in the future.

Signed-off-by: Linus Lüssing <linus.luessing@web.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
1 parent d41db9f
Raw File
random32.c
/*
  This is a maximally equidistributed combined Tausworthe generator
  based on code from GNU Scientific Library 1.5 (30 Jun 2004)

   x_n = (s1_n ^ s2_n ^ s3_n)

   s1_{n+1} = (((s1_n & 4294967294) <<12) ^ (((s1_n <<13) ^ s1_n) >>19))
   s2_{n+1} = (((s2_n & 4294967288) << 4) ^ (((s2_n << 2) ^ s2_n) >>25))
   s3_{n+1} = (((s3_n & 4294967280) <<17) ^ (((s3_n << 3) ^ s3_n) >>11))

   The period of this generator is about 2^88.

   From: P. L'Ecuyer, "Maximally Equidistributed Combined Tausworthe
   Generators", Mathematics of Computation, 65, 213 (1996), 203--213.

   This is available on the net from L'Ecuyer's home page,

   http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme.ps
   ftp://ftp.iro.umontreal.ca/pub/simulation/lecuyer/papers/tausme.ps

   There is an erratum in the paper "Tables of Maximally
   Equidistributed Combined LFSR Generators", Mathematics of
   Computation, 68, 225 (1999), 261--269:
   http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme2.ps

        ... the k_j most significant bits of z_j must be non-
        zero, for each j. (Note: this restriction also applies to the
        computer code given in [4], but was mistakenly not mentioned in
        that paper.)

   This affects the seeding procedure by imposing the requirement
   s1 > 1, s2 > 7, s3 > 15.

*/

#include <linux/types.h>
#include <linux/percpu.h>
#include <linux/module.h>
#include <linux/jiffies.h>
#include <linux/random.h>

static DEFINE_PER_CPU(struct rnd_state, net_rand_state);

/**
 *	prandom32 - seeded pseudo-random number generator.
 *	@state: pointer to state structure holding seeded state.
 *
 *	This is used for pseudo-randomness with no outside seeding.
 *	For more random results, use random32().
 */
u32 prandom32(struct rnd_state *state)
{
#define TAUSWORTHE(s,a,b,c,d) ((s&c)<<d) ^ (((s <<a) ^ s)>>b)

	state->s1 = TAUSWORTHE(state->s1, 13, 19, 4294967294UL, 12);
	state->s2 = TAUSWORTHE(state->s2, 2, 25, 4294967288UL, 4);
	state->s3 = TAUSWORTHE(state->s3, 3, 11, 4294967280UL, 17);

	return (state->s1 ^ state->s2 ^ state->s3);
}
EXPORT_SYMBOL(prandom32);

/**
 *	random32 - pseudo random number generator
 *
 *	A 32 bit pseudo-random number is generated using a fast
 *	algorithm suitable for simulation. This algorithm is NOT
 *	considered safe for cryptographic use.
 */
u32 random32(void)
{
	unsigned long r;
	struct rnd_state *state = &get_cpu_var(net_rand_state);
	r = prandom32(state);
	put_cpu_var(state);
	return r;
}
EXPORT_SYMBOL(random32);

/**
 *	srandom32 - add entropy to pseudo random number generator
 *	@seed: seed value
 *
 *	Add some additional seeding to the random32() pool.
 */
void srandom32(u32 entropy)
{
	int i;
	/*
	 * No locking on the CPUs, but then somewhat random results are, well,
	 * expected.
	 */
	for_each_possible_cpu (i) {
		struct rnd_state *state = &per_cpu(net_rand_state, i);
		state->s1 = __seed(state->s1 ^ entropy, 1);
	}
}
EXPORT_SYMBOL(srandom32);

/*
 *	Generate some initially weak seeding values to allow
 *	to start the random32() engine.
 */
static int __init random32_init(void)
{
	int i;

	for_each_possible_cpu(i) {
		struct rnd_state *state = &per_cpu(net_rand_state,i);

#define LCG(x)	((x) * 69069)	/* super-duper LCG */
		state->s1 = __seed(LCG(i + jiffies), 1);
		state->s2 = __seed(LCG(state->s1), 7);
		state->s3 = __seed(LCG(state->s2), 15);

		/* "warm it up" */
		prandom32(state);
		prandom32(state);
		prandom32(state);
		prandom32(state);
		prandom32(state);
		prandom32(state);
	}
	return 0;
}
core_initcall(random32_init);

/*
 *	Generate better values after random number generator
 *	is fully initialized.
 */
static int __init random32_reseed(void)
{
	int i;

	for_each_possible_cpu(i) {
		struct rnd_state *state = &per_cpu(net_rand_state,i);
		u32 seeds[3];

		get_random_bytes(&seeds, sizeof(seeds));
		state->s1 = __seed(seeds[0], 1);
		state->s2 = __seed(seeds[1], 7);
		state->s3 = __seed(seeds[2], 15);

		/* mix it in */
		prandom32(state);
	}
	return 0;
}
late_initcall(random32_reseed);
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