1 /*- 2 * Copyright (c) 1990, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * Posix rand_r function added May 1999 by Wes Peters <wes@softweyr.com>. 34 * 35 * $FreeBSD: src/lib/libc/stdlib/rand.c,v 1.2.2.1 2001/03/05 11:33:57 obrien Exp $ 36 * $DragonFly: src/lib/libc/stdlib/rand.c,v 1.2 2003/06/17 04:26:46 dillon Exp $ 37 * 38 * @(#)rand.c 8.1 (Berkeley) 6/14/93 39 */ 40 41 #include <sys/types.h> 42 #include <stdlib.h> 43 44 #ifdef TEST 45 #include <stdio.h> 46 #endif /* TEST */ 47 48 static int 49 do_rand(unsigned long *ctx) 50 { 51 return ((*ctx = *ctx * 1103515245 + 12345) % ((u_long)RAND_MAX + 1)); 52 } 53 54 55 int 56 rand_r(unsigned int *ctx) 57 { 58 u_long val = (u_long) *ctx; 59 *ctx = do_rand(&val); 60 return (int) *ctx; 61 } 62 63 64 static u_long next = 1; 65 66 int 67 rand() 68 { 69 return do_rand(&next); 70 } 71 72 void 73 srand(seed) 74 u_int seed; 75 { 76 next = seed; 77 } 78 79 #ifdef TEST 80 81 main() 82 { 83 int i; 84 unsigned myseed; 85 86 printf("seeding rand with 0x19610910: \n"); 87 srand(0x19610910); 88 89 printf("generating three pseudo-random numbers:\n"); 90 for (i = 0; i < 3; i++) 91 { 92 printf("next random number = %d\n", rand()); 93 } 94 95 printf("generating the same sequence with rand_r:\n"); 96 myseed = 0x19610910; 97 for (i = 0; i < 3; i++) 98 { 99 printf("next random number = %d\n", rand_r(&myseed)); 100 } 101 102 return 0; 103 } 104 105 #endif /* TEST */ 106 107