rogue/random.c

   1 /*      $NetBSD: random.c,v 1.4 1997/10/12 11:45:43 lukem Exp $ */
   2
   3 /*
   4  * Copyright (c) 1988, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * This code is derived from software contributed to Berkeley by
   8  * Timothy C. Stoehr.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. All advertising materials mentioning features or use of this software
  19  *    must display the following acknowledgement:
  20  *      This product includes software developed by the University of
  21  *      California, Berkeley and its contributors.
  22  * 4. Neither the name of the University nor the names of its contributors
  23  *    may be used to endorse or promote products derived from this software
  24  *    without specific prior written permission.
  25  *
  26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  36  * SUCH DAMAGE.
  37  */
  38
  39 #include <sys/cdefs.h>
  40 #ifndef lint
  41 #if 0
  42 static char sccsid[] = "@(#)random.c    8.1 (Berkeley) 5/31/93";
  43 #else
  44 __RCSID("$NetBSD: random.c,v 1.4 1997/10/12 11:45:43 lukem Exp $");
  45 #endif
  46 #endif /* not lint */
  47
  48 #include "rogue.h"
  49
  50 /*
  51  * random.c
  52  *
  53  * This source herein may be modified and/or distributed by anybody who
  54  * so desires, with the following restrictions:
  55  *    1.)  No portion of this notice shall be removed.
  56  *    2.)  Credit shall not be taken for the creation of this source.
  57  *    3.)  This code is not to be traded, sold, or used for personal
  58  *         gain or profit.
  59  *
  60  */
  61
  62 static long rntb[32] = {
  63                  3, 0x9a319039, 0x32d9c024, 0x9b663182, 0x5da1f342,
  64         0xde3b81e0, 0xdf0a6fb5, 0xf103bc02, 0x48f340fb, 0x7449e56b,
  65         0xbeb1dbb0, 0xab5c5918, 0x946554fd, 0x8c2e680f, 0xeb3d799f,
  66         0xb11ee0b7, 0x2d436b86, 0xda672e2a, 0x1588ca88, 0xe369735d,
  67         0x904f35f7, 0xd7158fd6, 0x6fa6f051, 0x616e6b96, 0xac94efdc,
  68         0x36413f93, 0xc622c298, 0xf5a42ab8, 0x8a88d77b, 0xf5ad9d0e,
  69         0x8999220b, 0x27fb47b9
  70 };
  71
  72 static long *fptr = &rntb[4];
  73 static long *rptr = &rntb[1];
  74 static long *state = &rntb[1];
  75 static int rand_type = 3;
  76 static int rand_deg = 31;
  77 static int rand_sep = 3;
  78 static long *end_ptr = &rntb[32];
  79
  80 void
  81 srrandom(x)
  82         int x;
  83 {
  84         int i;
  85
  86         state[0] = (long) x;
  87         if (rand_type != 0) {
  88                 for (i = 1; i < rand_deg; i++) {
  89                         state[i] = 1103515245 * state[i - 1] + 12345;
  90                 }
  91                 fptr = &state[rand_sep];
  92                 rptr = &state[0];
  93                 for (i = 0; i < 10 * rand_deg; i++) {
  94                         (void) rrandom();
  95                 }
  96         }
  97 }
  98
  99 long
 100 rrandom()
 101 {
 102         long i;
 103
 104         if (rand_type == 0) {
 105                 i = state[0] = (state[0]*1103515245 + 12345) & 0x7fffffff;
 106         } else {
 107                 *fptr += *rptr;
 108                 i = (*fptr >> 1) & 0x7fffffff;
 109                 if (++fptr >= end_ptr) {
 110                         fptr = state;
 111                         ++rptr;
 112                 } else {
 113                         if (++rptr >= end_ptr) {
 114                                 rptr = state;
 115                         }
 116                 }
 117         }
 118         return(i);
 119 }
 120
 121 int
 122 get_rand(x, y)
 123         int x, y;
 124 {
 125         int r, t;
 126         long lr;
 127
 128         if (x > y) {
 129                 t = y;
 130                 y = x;
 131                 x = t;
 132         }
 133         lr = rrandom();
 134         lr &= (long) 0x00003fff;
 135         r = (int) lr;
 136         r = (r % ((y - x) + 1)) + x;
 137         return(r);
 138 }
 139
 140 int
 141 rand_percent(percentage)
 142         int percentage;
 143 {
 144         return(get_rand(1, 100) <= percentage);
 145 }
 146
 147 int
 148 coin_toss()
 149 {
 150         return(((rrandom() & 01) ? 1 : 0));
 151 }