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