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/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License, Version 1.0 only
* (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 1996 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
/* Copyright (c) 1984 AT&T */
/* All Rights Reserved */
#pragma ident "%Z%%M% %I% %E% SMI"
/*LINTLIBRARY*/
/*
* 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.
*/
#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) { long l = (long)(x) * (long)(y); \
(z)[0] = LOW(l); (z)[1] = HIGH(l); }
#define CARRY(x, y) ((long)(x) + (long)(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) \
TYPE f(xsubi) \
register unsigned short *xsubi; \
{ \
register int i; \
register TYPE v; \
unsigned temp[3]; \
\
for (i = 0; i < 3; i++) { \
temp[i] = x[i]; \
x[i] = LOW(xsubi[i]); \
} \
v = F(); \
REST(v); \
}
static unsigned x[3] = { X0, X1, X2 }, a[3] = { A0, A1, A2 }, c = C;
static unsigned short lastx[3];
static void next();
double
drand48()
{
static double two16m = 1.0 / (1L << N);
next();
return (two16m * (two16m * (two16m * x[0] + x[1]) + x[2]));
}
NEST(double, erand48, drand48)
long
lrand48()
{
next();
return (((long)x[2] << (N - 1)) + (x[1] >> 1));
}
long
mrand48()
{
next();
return (((long)x[2] << N) + x[1]);
}
static void
next()
{
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
srand48(seedval)
long seedval;
{
SEED(X0, LOW(seedval), HIGH(seedval));
}
unsigned short *
seed48(seed16v)
unsigned short seed16v[3];
{
SETLOW(lastx, x, 0);
SEED(LOW(seed16v[0]), LOW(seed16v[1]), LOW(seed16v[2]));
return (lastx);
}
void
lcong48(param)
unsigned short param[7];
{
SETLOW(x, param, 0);
SETLOW(a, param, 3);
c = LOW(param[6]);
}
NEST(long, nrand48, lrand48)
NEST(long, jrand48, mrand48)
#ifdef DRIVER
/*
* This should print the sequences of integers in Tables 2
* and 1 of the TM:
* 1623, 3442, 1447, 1829, 1305, ...
* 657EB7255101, D72A0C966378, 5A743C062A23, ...
*/
#include <stdio.h>
main()
{
int i;
for (i = 0; i < 80; i++) {
printf("%4d ", (int)(4096 * drand48()));
printf("%.4X%.4X%.4X\n", x[2], x[1], x[0]);
}
}
#endif
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