/** * @file llrand.h * @brief Information, functions, and typedefs for randomness. * * $LicenseInfo:firstyear=2000&license=viewergpl$ * * Copyright (c) 2000-2009, Linden Research, Inc. * * Second Life Viewer Source Code * The source code in this file ("Source Code") is provided by Linden Lab * to you under the terms of the GNU General Public License, version 2.0 * ("GPL"), unless you have obtained a separate licensing agreement * ("Other License"), formally executed by you and Linden Lab. Terms of * the GPL can be found in doc/GPL-license.txt in this distribution, or * online at http://secondlifegrid.net/programs/open_source/licensing/gplv2 * * There are special exceptions to the terms and conditions of the GPL as * it is applied to this Source Code. View the full text of the exception * in the file doc/FLOSS-exception.txt in this software distribution, or * online at * http://secondlifegrid.net/programs/open_source/licensing/flossexception * * By copying, modifying or distributing this software, you acknowledge * that you have read and understood your obligations described above, * and agree to abide by those obligations. * * ALL LINDEN LAB SOURCE CODE IS PROVIDED "AS IS." LINDEN LAB MAKES NO * WARRANTIES, EXPRESS, IMPLIED OR OTHERWISE, REGARDING ITS ACCURACY, * COMPLETENESS OR PERFORMANCE. * $/LicenseInfo$ */ #ifndef LL_LLRAND_H #define LL_LLRAND_H #include <boost/random/lagged_fibonacci.hpp> #include <boost/random/mersenne_twister.hpp> /** * Use the boost random number generators if you want a stateful * random numbers. If you want more random numbers, use the * c-functions since they will generate faster/better randomness * across the process. * * I tested some of the boost random engines, and picked a good double * generator and a good integer generator. I also took some timings * for them on linux using gcc 3.3.5. The harness also did some other * fairly trivial operations to try to limit compiler optimizations, * so these numbers are only good for relative comparisons. * * usec/inter algorithm * 0.21 boost::minstd_rand0 * 0.039 boost:lagged_fibonacci19937 * 0.036 boost:lagged_fibonacci607 * 0.44 boost::hellekalek1995 * 0.44 boost::ecuyer1988 * 0.042 boost::rand48 * 0.043 boost::mt11213b * 0.028 stdlib random() * 0.05 stdlib lrand48() * 0.034 stdlib rand() * 0.020 the old & lame LLRand */ /** *@brief Generate a float from [0, RAND_MAX). */ S32 LL_COMMON_API ll_rand(); /** *@brief Generate a float from [0, val) or (val, 0]. */ S32 LL_COMMON_API ll_rand(S32 val); /** *@brief Generate a float from [0, 1.0). */ F32 LL_COMMON_API ll_frand(); /** *@brief Generate a float from [0, val) or (val, 0]. */ F32 LL_COMMON_API ll_frand(F32 val); /** *@brief Generate a double from [0, 1.0). */ F64 LL_COMMON_API ll_drand(); /** *@brief Generate a double from [0, val) or (val, 0]. */ F64 LL_COMMON_API ll_drand(F64 val); /** * @brief typedefs for good boost lagged fibonacci. * @see boost::lagged_fibonacci * * These generators will quickly generate doubles. Note the memory * requirements, because they are somewhat high. I chose the smallest * one, and one comparable in speed but higher periodicity without * outrageous memory requirements. * To use: * LLRandLagFib607 foo((U32)time(NULL)); * double bar = foo(); */ typedef boost::lagged_fibonacci607 LLRandLagFib607; /**< * lengh of cycle: 2^32,000 * memory: 607*sizeof(double) (about 5K) */ typedef boost::lagged_fibonacci2281 LLRandLagFib2281; /**< * lengh of cycle: 2^120,000 * memory: 2281*sizeof(double) (about 17K) */ /** * @breif typedefs for a good boost mersenne twister implementation. * @see boost::mersenne_twister * * This fairly quickly generates U32 values * To use: * LLRandMT19937 foo((U32)time(NULL)); * U32 bar = foo(); * * lengh of cycle: 2^19,937-1 * memory: about 2496 bytes */ typedef boost::mt11213b LLRandMT19937; #endif