/*

 * 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 2008 Sun Microsystems, Inc.  All rights reserved.

 * Use is subject to license terms.

 */

/*	Copyright (c) 1988 AT&T	*/

/*	  All Rights Reserved  	*/

#pragma ident	"%Z%%M%	%I%	%E% SMI"

/*

 *	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 "lint.h"

#include <mtlib.h>

#include <synch.h>

#include <thread.h>

static mutex_t seed_lock = DEFAULTMUTEX;

#define	EXPORT0(TYPE, fn, fnu)	TYPE fn() { \

	TYPE res; \

	lmutex_lock(&seed_lock); \

	res = fnu(); \

	lmutex_unlock(&seed_lock); \

	return (res); }

#define	EXPORT1(TYPE, fn, fnu)	TYPE fn(unsigned short xsubi[3]) { \

	TYPE res; \

	lmutex_lock(&seed_lock); \

	res = fnu(xsubi); \

	lmutex_unlock(&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 double

_drand48_u(void)

{

	static double two16m = 1.0 / ((int32_t)1 << N);

	next();

	return (two16m * (two16m * (two16m * x[0] + x[1]) + x[2]));

}

NEST(double, _erand48_u, _drand48_u)

static long

_lrand48_u(void)

{

	next();

	return ((long)((int32_t)x[2] << (N - 1)) + (x[1] >> 1));

}

static long

_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

srand48(long seedval)

{

	int32_t fixseed = (int32_t)seedval;	/* limit to 32 bits */

	lmutex_lock(&seed_lock);

	SEED(X0, LOW(fixseed), HIGH(fixseed));

	lmutex_unlock(&seed_lock);

}

unsigned short *

seed48(unsigned short seed16v[3])

{

	lmutex_lock(&seed_lock);

	SETLOW(lastx, x, 0);

	SEED(LOW(seed16v[0]), LOW(seed16v[1]), LOW(seed16v[2]));

	lmutex_unlock(&seed_lock);

	return (lastx);

}

void

lcong48(unsigned short param[7])

{

	lmutex_lock(&seed_lock);

	SETLOW(x, param, 0);

	SETLOW(a, param, 3);

	c = LOW(param[6]);

	lmutex_unlock(&seed_lock);

}

NEST(long, _nrand48_u, _lrand48_u)

NEST(long, _jrand48_u, _mrand48_u)

EXPORT0(double, drand48, _drand48_u)

EXPORT1(double, erand48, _erand48_u)

EXPORT0(long, lrand48, _lrand48_u)

EXPORT1(long, nrand48, _nrand48_u)

EXPORT0(long, mrand48, _mrand48_u)

EXPORT1(long, jrand48, _jrand48_u)

#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