lrandom.c

OXCC is a multipass, interpreting C compiler with several language extensions. It generates an Archi

/* ================ Random Number Generator from BSD ======================= */

/*
 * Copyright (c) 1983 Regents of the University of California.
 * All rights reserved.
 * modified by NORMAN D. CULVER Oxbow Software
 * Redistribution and use in source and binary forms are permitted
 * provided that: (1) source distributions retain this entire copyright
 * notice and comment, and (2) distributions including binaries display
 * the following acknowledgement:  ``This product includes software
 * developed by the University of California, Berkeley and its contributors''
 * in the documentation or other materials provided with the distribution
 * and in all advertising materials mentioning features or use of this
 * software. Neither the name of the University nor the names of its
 * contributors may be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

static long randtbl[32]	= { 0L,
	0x9a319039L, 0x32d9c024L, 0x9b663182L, 0x5da1f342L, 
	0xde3b81e0L, 0xdf0a6fb5L, 0xf103bc02L, 0x48f340fbL, 
	0x7449e56bL, 0xbeb1dbb0L, 0xab5c5918L, 0x946554fdL, 
	0x8c2e680fL, 0xeb3d799fL, 0xb11ee0b7L, 0x2d436b86L, 
	0xda672e2aL, 0x1588ca88L, 0xe369735dL, 0x904f35f7L, 
	0xd7158fd6L, 0x6fa6f051L, 0x616e6b96L, 0xac94efdcL, 
	0x36413f93L, 0xc622c298L, 0xf5a42ab8L, 0x8a88d77bL, 
	0xf5ad9d0eL, 0x8999220bL, 0x27fb47b9L
};

static  long *fptr	= &randtbl[4];
static  long *rptr	= &randtbl[1];

/*
 * Returns a really good 31-bit random number.
 */
static long
lrandom()
{
long i;
	
	*fptr += *rptr;
	i = (*fptr >> 1) & 0x7fffffffUL;	/* chucking least random bit */
	if(++fptr > &randtbl[31])
	{
		fptr = &randtbl[1];
		++rptr;
	}
	else
	{
		if(++rptr > &randtbl[31])  
			rptr = &randtbl[1];
	}
	return( i );
}
/* ========================= END Random Number Generator ==================== */