random.cc revision 7575:0002812cefe5
1/* 2 * Copyright (c) 2003-2005 The Regents of The University of Michigan 3 * 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 are 7 * met: redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer; 9 * redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution; 12 * neither the name of the copyright holders nor the names of its 13 * contributors may be used to endorse or promote products derived from 14 * this software without specific prior written permission. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 17 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 18 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 19 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 20 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 21 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 22 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 26 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 * 28 * Authors: Nathan Binkert 29 * Ali Saidi 30 */ 31 32#include "base/fenv.hh" 33#include "base/intmath.hh" 34#include "base/misc.hh" 35#include "base/random.hh" 36#include "sim/serialize.hh" 37 38using namespace std; 39 40Random::Random() 41{ 42 // default random seed taken from original source 43 init(5489); 44} 45 46Random::Random(uint32_t s) 47{ 48 init(s); 49} 50 51Random::Random(uint32_t init_key[], int key_length) 52{ 53 init(init_key, key_length); 54} 55 56Random::~Random() 57{ 58} 59 60// To preserve the uniform random distribution between min and max, 61// and allow all numbers to be represented, we generate a uniform 62// random number to the nearest power of two greater than max. If 63// this number doesn't fall between 0 and max, we try again. Anything 64// else would skew the distribution. 65uint32_t 66Random::genrand(uint32_t max) 67{ 68 if (max == 0) 69 return 0; 70 int log = ceilLog2(max) + 1; 71 int shift = (sizeof(uint32_t) * 8 - log); 72 uint32_t random; 73 74 do { 75 random = genrand() >> shift; 76 } while (random > max); 77 78 return random; 79} 80 81uint64_t 82Random::genrand(uint64_t max) 83{ 84 if (max == 0) 85 return 0; 86 int log = ceilLog2(max) + 1; 87 int shift = (sizeof(uint64_t) * 8 - log); 88 uint64_t random; 89 90 do { 91 random = (uint64_t)genrand() << 32 | (uint64_t)genrand(); 92 random = random >> shift; 93 } while (random > max); 94 95 return random; 96} 97 98void 99Random::serialize(const string &base, ostream &os) 100{ 101 int length = N; 102 paramOut(os, base + ".mti", mti); 103 paramOut(os, base + ".length", length); 104 arrayParamOut(os, base + ".data", mt, length); 105} 106 107void 108Random::unserialize(const string &base, Checkpoint *cp, const string §ion) 109{ 110 int length; 111 112 paramIn(cp, section, base + ".mti", mti); 113 paramIn(cp, section, base + ".length", length); 114 if (length != N) 115 panic("cant unserialize random number data. length != %d\n", length); 116 117 arrayParamIn(cp, section, base + ".data", mt, length); 118} 119 120Random random_mt; 121