1 /*- 2 * Portions Copyright (c) 2010, Intel Corporation. All rights reserved.<BR> 3 * Copyright (c) 1990, 1993 4 * The Regents of the University of California. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 4. Neither the name of the University nor the names of its contributors 15 * may be used to endorse or promote products derived from this software 16 * without specific prior written permission. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28 * SUCH DAMAGE. 29 * 30 */ 31 //__FBSDID("$FreeBSD: src/lib/libc/stdlib/rand.c,v 1.17.2.1.2.1 2009/10/25 01:10:29 kensmith Exp $"); 32 #include <LibConfig.h> 33 34 #include <stdlib.h> 35 36 static UINT32 next = 1; 37 38 /** Compute a pseudo-random number. 39 * 40 * Compute x = (7^5 * x) mod (2^31 - 1) 41 * without overflowing 31 bits: 42 * (2^31 - 1) = 127773 * (7^5) + 2836 43 * From "Random number generators: good ones are hard to find", 44 * Park and Miller, Communications of the ACM, vol. 31, no. 10, 45 * October 1988, p. 1195. 46 **/ 47 int 48 rand() 49 { 50 INT32 hi, lo, x; 51 52 /* Can't be initialized with 0, so use another value. */ 53 if (next == 0) 54 next = 123459876; 55 hi = next / 127773; 56 lo = next % 127773; 57 x = 16807 * lo - 2836 * hi; 58 if (x < 0) 59 x += 0x7fffffff; 60 return ((next = x) % ((UINT32)RAND_MAX + 1)); 61 } 62 63 void 64 srand(unsigned int seed) 65 { 66 next = (UINT32)seed; 67 } 68
