rogue/random.c

   1 /*      $NetBSD: random.c,v 1.5 2003/08/07 09:37:39 agc 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. Neither the name of the University nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  */
  34
  35 #include <sys/cdefs.h>
  36 #ifndef lint
  37 #if 0
  38 static char sccsid[] = "@(#)random.c    8.1 (Berkeley) 5/31/93";
  39 #else
  40 __RCSID("$NetBSD: random.c,v 1.5 2003/08/07 09:37:39 agc Exp $");
  41 #endif
  42 #endif /* not lint */
  43
  44 #include "rogue.h"
  45
  46 /*
  47  * random.c
  48  *
  49  * This source herein may be modified and/or distributed by anybody who
  50  * so desires, with the following restrictions:
  51  *    1.)  No portion of this notice shall be removed.
  52  *    2.)  Credit shall not be taken for the creation of this source.
  53  *    3.)  This code is not to be traded, sold, or used for personal
  54  *         gain or profit.
  55  *
  56  */
  57
  58 static long rntb[32] = {
  59                  3, 0x9a319039, 0x32d9c024, 0x9b663182, 0x5da1f342,
  60         0xde3b81e0, 0xdf0a6fb5, 0xf103bc02, 0x48f340fb, 0x7449e56b,
  61         0xbeb1dbb0, 0xab5c5918, 0x946554fd, 0x8c2e680f, 0xeb3d799f,
  62         0xb11ee0b7, 0x2d436b86, 0xda672e2a, 0x1588ca88, 0xe369735d,
  63         0x904f35f7, 0xd7158fd6, 0x6fa6f051, 0x616e6b96, 0xac94efdc,
  64         0x36413f93, 0xc622c298, 0xf5a42ab8, 0x8a88d77b, 0xf5ad9d0e,
  65         0x8999220b, 0x27fb47b9
  66 };
  67
  68 static long *fptr = &rntb[4];
  69 static long *rptr = &rntb[1];
  70 static long *state = &rntb[1];
  71 static int rand_type = 3;
  72 static int rand_deg = 31;
  73 static int rand_sep = 3;
  74 static long *end_ptr = &rntb[32];
  75
  76 void
  77 srrandom(x)
  78         int x;
  79 {
  80         int i;
  81
  82         state[0] = (long) x;
  83         if (rand_type != 0) {
  84                 for (i = 1; i < rand_deg; i++) {
  85                         state[i] = 1103515245 * state[i - 1] + 12345;
  86                 }
  87                 fptr = &state[rand_sep];
  88                 rptr = &state[0];
  89                 for (i = 0; i < 10 * rand_deg; i++) {
  90                         (void) rrandom();
  91                 }
  92         }
  93 }
  94
  95 long
  96 rrandom()
  97 {
  98         long i;
  99
 100         if (rand_type == 0) {
 101                 i = state[0] = (state[0]*1103515245 + 12345) & 0x7fffffff;
 102         } else {
 103                 *fptr += *rptr;
 104                 i = (*fptr >> 1) & 0x7fffffff;
 105                 if (++fptr >= end_ptr) {
 106                         fptr = state;
 107                         ++rptr;
 108                 } else {
 109                         if (++rptr >= end_ptr) {
 110                                 rptr = state;
 111                         }
 112                 }
 113         }
 114         return(i);
 115 }
 116
 117 int
 118 get_rand(x, y)
 119         int x, y;
 120 {
 121         int r, t;
 122         long lr;
 123
 124         if (x > y) {
 125                 t = y;
 126                 y = x;
 127                 x = t;
 128         }
 129         lr = rrandom();
 130         lr &= (long) 0x00003fff;
 131         r = (int) lr;
 132         r = (r % ((y - x) + 1)) + x;
 133         return(r);
 134 }
 135
 136 int
 137 rand_percent(percentage)
 138         int percentage;
 139 {
 140         return(get_rand(1, 100) <= percentage);
 141 }
 142
 143 int
 144 coin_toss()
 145 {
 146         return(((rrandom() & 01) ? 1 : 0));
 147 }