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 */ 37 38 #if defined(LIBC_SCCS) && !defined(lint) 39 static char sccsid[] = "@(#)rand.c 8.1 (Berkeley) 6/14/93"; 40 #endif /* LIBC_SCCS and not lint */ 41 42 #include <sys/types.h> 43 #include <stdlib.h> 44 45 #ifdef TEST 46 #include <stdio.h> 47 #endif /* TEST */ 48 49 static int 50 do_rand(unsigned long *ctx) 51 { 52 return ((*ctx = *ctx * 1103515245 + 12345) % ((u_long)RAND_MAX + 1)); 53 } 54 55 56 int 57 rand_r(unsigned int *ctx) 58 { 59 u_long val = (u_long) *ctx; 60 *ctx = do_rand(&val); 61 return (int) *ctx; 62 } 63 64 65 static u_long next = 1; 66 67 int 68 rand() 69 { 70 return do_rand(&next); 71 } 72 73 void 74 srand(seed) 75 u_int seed; 76 { 77 next = seed; 78 } 79 80 #ifdef TEST 81 82 main() 83 { 84 int i; 85 unsigned myseed; 86 87 printf("seeding rand with 0x19610910: \n"); 88 srand(0x19610910); 89 90 printf("generating three pseudo-random numbers:\n"); 91 for (i = 0; i < 3; i++) 92 { 93 printf("next random number = %d\n", rand()); 94 } 95 96 printf("generating the same sequence with rand_r:\n"); 97 myseed = 0x19610910; 98 for (i = 0; i < 3; i++) 99 { 100 printf("next random number = %d\n", rand_r(&myseed)); 101 } 102 103 return 0; 104 } 105 106 #endif /* TEST */ 107 108