Home | History | Annotate | Line # | Download | only in rogue
random.c revision 1.1 
      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[] = "@(#)random.c	5.3 (Berkeley) 6/1/90";
     39 #endif /* not lint */
     40 
     41 /*
     42  * random.c
     43  *
     44  * This source herein may be modified and/or distributed by anybody who
     45  * so desires, with the following restrictions:
     46  *    1.)  No portion of this notice shall be removed.
     47  *    2.)  Credit shall not be taken for the creation of this source.
     48  *    3.)  This code is not to be traded, sold, or used for personal
     49  *         gain or profit.
     50  *
     51  */
     52 
     53 static long rntb[32] = {
     54 	         3, 0x9a319039, 0x32d9c024, 0x9b663182, 0x5da1f342,
     55 	0xde3b81e0, 0xdf0a6fb5, 0xf103bc02, 0x48f340fb, 0x7449e56b,
     56 	0xbeb1dbb0, 0xab5c5918, 0x946554fd, 0x8c2e680f, 0xeb3d799f,
     57 	0xb11ee0b7, 0x2d436b86, 0xda672e2a, 0x1588ca88, 0xe369735d,
     58 	0x904f35f7, 0xd7158fd6, 0x6fa6f051, 0x616e6b96, 0xac94efdc,
     59 	0x36413f93, 0xc622c298, 0xf5a42ab8, 0x8a88d77b, 0xf5ad9d0e,
     60 	0x8999220b, 0x27fb47b9
     61 };
     62 
     63 static long *fptr = &rntb[4];
     64 static long *rptr = &rntb[1];
     65 static long *state = &rntb[1];
     66 static int rand_type = 3;
     67 static int rand_deg = 31;
     68 static int rand_sep = 3;
     69 static long *end_ptr = &rntb[32];
     70 
     71 srrandom(x)
     72 int x;
     73 {
     74 	register int i;
     75 	long rrandom();
     76 
     77 	state[0] = (long) x;
     78 	if (rand_type != 0) {
     79 		for (i = 1; i < rand_deg; i++) {
     80 			state[i] = 1103515245 * state[i - 1] + 12345;
     81 		}
     82 		fptr = &state[rand_sep];
     83 		rptr = &state[0];
     84 		for (i = 0; i < 10 * rand_deg; i++) {
     85 			(void) rrandom();
     86 		}
     87 	}
     88 }
     89 
     90 long
     91 rrandom()
     92 {
     93 	long i;
     94 
     95 	if (rand_type == 0) {
     96 		i = state[0] = (state[0]*1103515245 + 12345) & 0x7fffffff;
     97 	} else {
     98 		*fptr += *rptr;
     99 		i = (*fptr >> 1) & 0x7fffffff;
    100 		if (++fptr >= end_ptr) {
    101 			fptr = state;
    102 			++rptr;
    103 		} else {
    104 			if (++rptr >= end_ptr) {
    105 				rptr = state;
    106 			}
    107 		}
    108 	}
    109 	return(i);
    110 }
    111 
    112 get_rand(x, y)
    113 register int x, y;
    114 {
    115 	register int r, t;
    116 	long lr;
    117 
    118 	if (x > y) {
    119 		t = y;
    120 		y = x;
    121 		x = t;
    122 	}
    123 	lr = rrandom();
    124 	lr &= (long) 0x00003fff;
    125 	r = (int) lr;
    126 	r = (r % ((y - x) + 1)) + x;
    127 	return(r);
    128 }
    129 
    130 rand_percent(percentage)
    131 register int percentage;
    132 {
    133 	return(get_rand(1, 100) <= percentage);
    134 }
    135 
    136 coin_toss()
    137 {
    138 
    139 	return(((rrandom() & 01) ? 1 : 0));
    140 }
    141