rogue/random.c

   1 /*
   2  * Copyright (c) 1988 The Regents of the University of California.
   3  * All rights reserved.
   4  *
   5  * This code is derived from software contributed to Berkeley by
   6  * Timothy C. Stoehr.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. All advertising materials mentioning features or use of this software
  17  *    must display the following acknowledgement:
  18  *      This product includes software developed by the University of
  19  *      California, Berkeley and its contributors.
  20  * 4. Neither the name of the University nor the names of its contributors
  21  *    may be used to endorse or promote products derived from this software
  22  *    without specific prior written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  */
  36
  37 #ifndef lint
  38 /*static char sccsid[] = "from: @(#)random.c    5.3 (Berkeley) 6/1/90";*/
  39 static char rcsid[] = "$Id: random.c,v 1.2 1993/08/01 18:52:18 mycroft Exp $";
  40 #endif /* not lint */
  41
  42 /*
  43  * random.c
  44  *
  45  * This source herein may be modified and/or distributed by anybody who
  46  * so desires, with the following restrictions:
  47  *    1.)  No portion of this notice shall be removed.
  48  *    2.)  Credit shall not be taken for the creation of this source.
  49  *    3.)  This code is not to be traded, sold, or used for personal
  50  *         gain or profit.
  51  *
  52  */
  53
  54 static long rntb[32] = {
  55                  3, 0x9a319039, 0x32d9c024, 0x9b663182, 0x5da1f342,
  56         0xde3b81e0, 0xdf0a6fb5, 0xf103bc02, 0x48f340fb, 0x7449e56b,
  57         0xbeb1dbb0, 0xab5c5918, 0x946554fd, 0x8c2e680f, 0xeb3d799f,
  58         0xb11ee0b7, 0x2d436b86, 0xda672e2a, 0x1588ca88, 0xe369735d,
  59         0x904f35f7, 0xd7158fd6, 0x6fa6f051, 0x616e6b96, 0xac94efdc,
  60         0x36413f93, 0xc622c298, 0xf5a42ab8, 0x8a88d77b, 0xf5ad9d0e,
  61         0x8999220b, 0x27fb47b9
  62 };
  63
  64 static long *fptr = &rntb[4];
  65 static long *rptr = &rntb[1];
  66 static long *state = &rntb[1];
  67 static int rand_type = 3;
  68 static int rand_deg = 31;
  69 static int rand_sep = 3;
  70 static long *end_ptr = &rntb[32];
  71
  72 srrandom(x)
  73 int x;
  74 {
  75         register int i;
  76         long rrandom();
  77
  78         state[0] = (long) x;
  79         if (rand_type != 0) {
  80                 for (i = 1; i < rand_deg; i++) {
  81                         state[i] = 1103515245 * state[i - 1] + 12345;
  82                 }
  83                 fptr = &state[rand_sep];
  84                 rptr = &state[0];
  85                 for (i = 0; i < 10 * rand_deg; i++) {
  86                         (void) rrandom();
  87                 }
  88         }
  89 }
  90
  91 long
  92 rrandom()
  93 {
  94         long i;
  95
  96         if (rand_type == 0) {
  97                 i = state[0] = (state[0]*1103515245 + 12345) & 0x7fffffff;
  98         } else {
  99                 *fptr += *rptr;
 100                 i = (*fptr >> 1) & 0x7fffffff;
 101                 if (++fptr >= end_ptr) {
 102                         fptr = state;
 103                         ++rptr;
 104                 } else {
 105                         if (++rptr >= end_ptr) {
 106                                 rptr = state;
 107                         }
 108                 }
 109         }
 110         return(i);
 111 }
 112
 113 get_rand(x, y)
 114 register int x, y;
 115 {
 116         register int r, t;
 117         long lr;
 118
 119         if (x > y) {
 120                 t = y;
 121                 y = x;
 122                 x = t;
 123         }
 124         lr = rrandom();
 125         lr &= (long) 0x00003fff;
 126         r = (int) lr;
 127         r = (r % ((y - x) + 1)) + x;
 128         return(r);
 129 }
 130
 131 rand_percent(percentage)
 132 register int percentage;
 133 {
 134         return(get_rand(1, 100) <= percentage);
 135 }
 136
 137 coin_toss()
 138 {
 139
 140         return(((rrandom() & 01) ? 1 : 0));
 141 }