1 /* $NetBSD: random.c,v 1.7 2008/01/14 03:50:02 dholland 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 1.7 2008/01/14 03:50:02 dholland 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(int x) 78 { 79 int i; 80 81 state[0] = x; 82 if (rand_type != 0) { 83 for (i = 1; i < rand_deg; i++) { 84 state[i] = 1103515245 * state[i - 1] + 12345; 85 } 86 fptr = &state[rand_sep]; 87 rptr = &state[0]; 88 for (i = 0; i < 10 * rand_deg; i++) { 89 (void)rrandom(); 90 } 91 } 92 } 93 94 long 95 rrandom(void) 96 { 97 long i; 98 99 if (rand_type == 0) { 100 i = state[0] = (state[0]*1103515245 + 12345) & 0x7fffffff; 101 } else { 102 *fptr += *rptr; 103 i = (*fptr >> 1) & 0x7fffffff; 104 if (++fptr >= end_ptr) { 105 fptr = state; 106 ++rptr; 107 } else { 108 if (++rptr >= end_ptr) { 109 rptr = state; 110 } 111 } 112 } 113 return(i); 114 } 115 116 int 117 get_rand(int x, int y) 118 { 119 int r, t; 120 long lr; 121 122 if (x > y) { 123 t = y; 124 y = x; 125 x = t; 126 } 127 lr = rrandom(); 128 lr &= 0x00003fffL; 129 r = (int)lr; 130 r = (r % ((y - x) + 1)) + x; 131 return(r); 132 } 133 134 int 135 rand_percent(int percentage) 136 { 137 return(get_rand(1, 100) <= percentage); 138 } 139 140 int 141 coin_toss(void) 142 { 143 return(((rrandom() & 01) ? 1 : 0)); 144 } 145