| Sandrine Bailleux | 3cd87d7 | 2018-10-09 11:12:55 +0200 | [diff] [blame] | 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 <stdlib.h> |
| 33 | |
| 34 | static unsigned int next = 1; |
| 35 | |
| 36 | /** Compute a pseudo-random number. |
| 37 | * |
| 38 | * Compute x = (7^5 * x) mod (2^31 - 1) |
| 39 | * without overflowing 31 bits: |
| 40 | * (2^31 - 1) = 127773 * (7^5) + 2836 |
| 41 | * From "Random number generators: good ones are hard to find", |
| 42 | * Park and Miller, Communications of the ACM, vol. 31, no. 10, |
| 43 | * October 1988, p. 1195. |
| 44 | **/ |
| 45 | int |
| 46 | rand() |
| 47 | { |
| 48 | int hi, lo, x; |
| 49 | |
| 50 | /* Can't be initialized with 0, so use another value. */ |
| 51 | if (next == 0) |
| 52 | next = 123459876; |
| 53 | hi = next / 127773; |
| 54 | lo = next % 127773; |
| 55 | x = 16807 * lo - 2836 * hi; |
| 56 | if (x < 0) |
| 57 | x += 0x7fffffff; |
| 58 | return ((next = x) % ((unsigned int)RAND_MAX + 1)); |
| 59 | } |
| 60 | |
| 61 | void |
| 62 | srand(unsigned int seed) |
| 63 | { |
| 64 | next = (unsigned int)seed; |
| 65 | } |