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From: dibble@rochester.UUCP
Newsgroups: net.micro.6809
Subject: Re: Wanted: rnd() for os9 "C"
Message-ID: <19544@rochester.ARPA>
Date: Mon, 21-Jul-86 11:55:29 EDT
Article-I.D.: rocheste.19544
Posted: Mon Jul 21 11:55:29 1986
Date-Received: Wed, 23-Jul-86 07:16:18 EDT
References: <432@chinet.UUCP>
Distribution: net
Organization: U of Rochester, CS Dept., Rochester, NY
Lines: 36
Summary: Simple random # generator for OS-9

In article <432@chinet.UUCP>, megabyte@chinet.UUCP (Mark E. Sunderlin) writes:
> Does anyone have a good random number generator for use with
> the Microware 6809 os9 "C" compiler?
> 
> I'm looking for something like:
> random = rnd();   /* returns a random number (an int) */

I wrote this for my port of Hack.  It seems to work well (though I
haven't made any real effort to validate it).  You'll probably have to
shrink the constants for the 6809.  Check Knuth for directions on picking
good numbers.

setrandom() /* initialize the seed for random */
	{
		int time, date, tick;
		short day;
	
		_sysdate(2, &time, &date, &day, &tick);
		srand((time<<8) + (tick & 0xff));
	}

static unsigned long RandomSeed;
srand(seed)
	int seed;
	{
		RandomSeed = (unsigned long)seed;
	}

#define MULTIPLIER 39709L
#define INCREMENT 13L
#define MODULUS 65537
int rand()
	{
		RandomSeed = (RandomSeed * MULTIPLIER + INCREMENT) % MODULUS;
		return (int)(RandomSeed & 0x7FFFFFFF);
	}