usr/src/games/rogue/random.c

/*
 * Copyright (c) 1988 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. 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.
 */

#ifndef lint
static char sccsid[] = "@(#)random.c    5.3 (Berkeley) 6/1/90";
#endif /* not lint */

/*
 * 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];

srrandom(x)
int x;
{
        register int i;
        long rrandom();

        state[0] = (long) 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();
                }
        }
}

long
rrandom()
{
        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);
}

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

        if (x > y) {
                t = y;
                y = x;
                x = t;
        }
        lr = rrandom();
        lr &= (long) 0x00003fff;
        r = (int) lr;
        r = (r % ((y - x) + 1)) + x;
        return(r);
}

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

coin_toss()
{

        return(((rrandom() & 01) ? 1 : 0));
}