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Diffstat (limited to 'indra/llcommon/llrand.h')
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diff --git a/indra/llcommon/llrand.h b/indra/llcommon/llrand.h new file mode 100644 index 0000000000..5bd874ba83 --- /dev/null +++ b/indra/llcommon/llrand.h @@ -0,0 +1,132 @@ +/** + * @file llrand.h + * @brief Information, functions, and typedefs for randomness. + * + * $LicenseInfo:firstyear=2000&license=viewergpl$ + * + * Copyright (c) 2000-2007, 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://secondlife.com/developers/opensource/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://secondlife.com/developers/opensource/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_rand(); + +/** + *@brief Generate a float from [0, val) or (val, 0]. + */ +S32 ll_rand(S32 val); + +/** + *@brief Generate a float from [0, 1.0). + */ +F32 ll_frand(); + +/** + *@brief Generate a float from [0, val) or (val, 0]. + */ +F32 ll_frand(F32 val); + +/** + *@brief Generate a double from [0, 1.0). + */ +F64 ll_drand(); + +/** + *@brief Generate a double from [0, val) or (val, 0]. + */ +F64 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 |