/*      $NetBSD: random.c,v 1.8 2009/08/12 08:44:45 dholland Exp $      */

/*
* Copyright (c) 1988, 1993
*      The Regents of the University of California.  All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Timothy C. Stoehr.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in the
*    documentation and/or other materials provided with the distribution.
* 3. 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 BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/

#include <sys/cdefs.h>
#ifndef lint
#if 0
static char sccsid[] = "@(#)random.c    8.1 (Berkeley) 5/31/93";
#else
__RCSID("$NetBSD: random.c,v 1.8 2009/08/12 08:44:45 dholland Exp $");
#endif
#endif /* not lint */

#include "rogue.h"

/*
* random.c
*
* This source herein may be modified and/or distributed by anybody who
* so desires, with the following restrictions:
*    1.)  No portion of this notice shall be removed.
*    2.)  Credit shall not be taken for the creation of this source.
*    3.)  This code is not to be traded, sold, or used for personal
*         gain or profit.
*
*/

static long rntb[32] = {
                3, 0x9a319039, 0x32d9c024, 0x9b663182, 0x5da1f342,
       0xde3b81e0, 0xdf0a6fb5, 0xf103bc02, 0x48f340fb, 0x7449e56b,
       0xbeb1dbb0, 0xab5c5918, 0x946554fd, 0x8c2e680f, 0xeb3d799f,
       0xb11ee0b7, 0x2d436b86, 0xda672e2a, 0x1588ca88, 0xe369735d,
       0x904f35f7, 0xd7158fd6, 0x6fa6f051, 0x616e6b96, 0xac94efdc,
       0x36413f93, 0xc622c298, 0xf5a42ab8, 0x8a88d77b, 0xf5ad9d0e,
       0x8999220b, 0x27fb47b9
};

static long *fptr = &rntb[4];
static long *rptr = &rntb[1];
static long *state = &rntb[1];
static int rand_type = 3;
static int rand_deg = 31;
static int rand_sep = 3;
static long *end_ptr = &rntb[32];

static long rrandom(void);

void
srrandom(int x)
{
       int i;

       state[0] = x;
       if (rand_type != 0) {
               for (i = 1; i < rand_deg; i++) {
                       state[i] = 1103515245 * state[i - 1] + 12345;
               }
               fptr = &state[rand_sep];
               rptr = &state[0];
               for (i = 0; i < 10 * rand_deg; i++) {
                       (void)rrandom();
               }
       }
}

static long
rrandom(void)
{
       long i;

       if (rand_type == 0) {
               i = state[0] = (state[0]*1103515245 + 12345) & 0x7fffffff;
       } else {
               *fptr += *rptr;
               i = (*fptr >> 1) & 0x7fffffff;
               if (++fptr >= end_ptr) {
                       fptr = state;
                       ++rptr;
               } else {
                       if (++rptr >= end_ptr) {
                               rptr = state;
                       }
               }
       }
       return(i);
}

int
get_rand(int x, int y)
{
       int r, t;
       long lr;

       if (x > y) {
               t = y;
               y = x;
               x = t;
       }
       lr = rrandom();
       lr &= 0x00003fffL;
       r = (int)lr;
       r = (r % ((y - x) + 1)) + x;
       return(r);
}

int
rand_percent(int percentage)
{
       return(get_rand(1, 100) <= percentage);
}

int
coin_toss(void)
{
       return(((rrandom() & 01) ? 1 : 0));
}