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/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2009 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
/* Copyright (c) 1988 AT&T */
/* All Rights Reserved */
/*
* drand48, etc. pseudo-random number generator
* This implementation assumes unsigned short integers of at least
* 16 bits, long integers of at least 32 bits, and ignores
* overflows on adding or multiplying two unsigned integers.
* Two's-complement representation is assumed in a few places.
* Some extra masking is done if unsigneds are exactly 16 bits
* or longs are exactly 32 bits, but so what?
* An assembly-language implementation would run significantly faster.
*/
/*
* New assumptions (supercede those stated above) for 64-bit work.
* Longs are now 64 bits, and we are bound by standards to return
* type long, hovever all internal calculations where long was
* previously used (32 bit precision) are now using the int32_t
* type (32 bit precision in both ILP32 and LP64 worlds).
*/
#include <sys/mutex.h>
static kmutex_t seed_lock;
static int init48done = 0;
#define EXPORT0(TYPE, fn, fnu) TYPE fn() { \
TYPE res; \
mutex_enter(&seed_lock); \
res = fnu(); \
mutex_exit(&seed_lock); \
return (res); }
#define EXPORT1(TYPE, fn, fnu) TYPE fn(unsigned short xsubi[3]) { \
TYPE res; \
mutex_enter(&seed_lock); \
res = fnu(xsubi); \
mutex_exit(&seed_lock); \
return (res); }
#define N 16
#define MASK ((unsigned)(1 << (N - 1)) + (1 << (N - 1)) - 1)
#define LOW(x) ((unsigned)(x) & MASK)
#define HIGH(x) LOW((x) >> N)
#define MUL(x, y, z) { int32_t l = (int32_t)(x) * (int32_t)(y); \
(z)[0] = LOW(l); (z)[1] = HIGH(l); }
#define CARRY(x, y) ((int32_t)(x) + (int32_t)(y) > MASK)
#define ADDEQU(x, y, z) (z = CARRY(x, (y)), x = LOW(x + (y)))
#define X0 0x330E
#define X1 0xABCD
#define X2 0x1234
#define A0 0xE66D
#define A1 0xDEEC
#define A2 0x5
#define C 0xB
#define SET3(x, x0, x1, x2) ((x)[0] = (x0), (x)[1] = (x1), (x)[2] = (x2))
#define SETLOW(x, y, n) SET3(x, LOW((y)[n]), LOW((y)[(n)+1]), LOW((y)[(n)+2]))
#define SEED(x0, x1, x2) (SET3(x, x0, x1, x2), SET3(a, A0, A1, A2), c = C)
#define REST(v) for (i = 0; i < 3; i++) { xsubi[i] = x[i]; x[i] = temp[i]; } \
return (v)
#define NEST(TYPE, f, F) static TYPE f(unsigned short *xsubi) { \
int i; TYPE v; unsigned temp[3]; \
for (i = 0; i < 3; i++) { temp[i] = x[i]; x[i] = LOW(xsubi[i]); } \
v = F(); REST(v); }
/* Way ugly solution to problem names, but it works */
#define x _drand48_x
#define a _drand48_a
#define c _drand48_c
/* End way ugly */
static unsigned x[3] = { X0, X1, X2 }, a[3] = { A0, A1, A2 }, c = C;
static unsigned short lastx[3];
static void next(void);
static long
ipf_r_lrand48_u(void)
{
next();
return ((long)((int32_t)x[2] << (N - 1)) + (x[1] >> 1));
}
static void
init48(void)
{
mutex_init(&seed_lock, 0L, MUTEX_DRIVER, 0L);
init48done = 1;
}
static long
ipf_r_mrand48_u(void)
{
next();
return ((long)((int32_t)x[2] << N) + x[1]);
}
static void
next(void)
{
unsigned p[2], q[2], r[2], carry0, carry1;
MUL(a[0], x[0], p);
ADDEQU(p[0], c, carry0);
ADDEQU(p[1], carry0, carry1);
MUL(a[0], x[1], q);
ADDEQU(p[1], q[0], carry0);
MUL(a[1], x[0], r);
x[2] = LOW(carry0 + carry1 + CARRY(p[1], r[0]) + q[1] + r[1] +
a[0] * x[2] + a[1] * x[1] + a[2] * x[0]);
x[1] = LOW(p[1] + r[0]);
x[0] = LOW(p[0]);
}
void
ipf_r_srand48(long seedval)
{
int32_t fixseed = (int32_t)seedval; /* limit to 32 bits */
if (init48done == 0)
init48();
mutex_enter(&seed_lock);
SEED(X0, LOW(fixseed), HIGH(fixseed));
mutex_exit(&seed_lock);
}
EXPORT0(long, ipf_r_lrand48, ipf_r_lrand48_u)
#include <sys/random.h>
unsigned
ipf_random()
{
static int seeded = 0;
if (seeded == 0) {
long seed;
/*
* Keep reseeding until some good randomness comes from the
* kernel. One of two things will happen: it will succeed or
* it will fail (with poor randomness), thus creating NAT
* sessions will be "slow" until enough randomness is gained
* to not need to get more. It isn't necessary to initialise
* seed as it will just pickup whatever random garbage has
* been left on the heap and that's good enough until we
* get some good garbage.
*/
if (random_get_bytes((uint8_t *)&seed, sizeof (seed)) == 0)
seeded = 1;
ipf_r_srand48(seed);
}
return (unsigned)ipf_r_lrand48();
}
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