Merge pull request #1460 from EQEmu/feature/random_enhancements

[Feature] Add some knobs to our RNG class

CMakeLists.txt

@@ -131,6 +131,47 @@ OPTION(EQEMU_BUILD_TESTS "Build utility tests." OFF)
 OPTION(EQEMU_BUILD_CLIENT_FILES "Build Client Import/Export Data Programs." ON)
 OPTION(EQEMU_PREFER_LUA "Build with normal Lua even if LuaJIT is found." OFF)
 
+#PRNG options
+OPTION(EQEMU_ADDITIVE_LFIB_PRNG "Use Additive LFib for PRNG." OFF)
+MARK_AS_ADVANCED(EQEMU_ADDITIVE_LFIB_PRNG)
+OPTION(EQEMU_BIASED_INT_DIST "Use biased int dist instead of uniform." OFF)
+MARK_AS_ADVANCED(EQEMU_BIASED_INT_DIST)
+SET(EQEMU_CUSTOM_PRNG_ENGINE "" CACHE STRING "Custom random engine. (ex. std::default_random_engine)")
+MARK_AS_ADVANCED(EQEMU_CUSTOM_PRNG_ENGINE)
+
+IF(CMAKE_COMPILER_IS_GNUCXX)
+	OPTION(EQEMU_SFMT19937 "Use GCC's extention for SIMD Fast MT19937." OFF)
+	MARK_AS_ADVANCED(EQEMU_SFMT19937)
+ENDIF()
+
+IF(EQEMU_ADDITIVE_LFIB_PRNG)
+	ADD_DEFINITIONS(-DUSE_ADDITIVE_LFIB_PRNG)
+	IF(EQEMU_SFMT19937)
+		MESSAGE(STATUS "SFMT19937 and ADDITITVE_LFIB_PRNG both set, SFMT19937 ignored.")
+		SET(EQEMU_SFMT19937 OFF)
+	ENDIF()
+	IF(NOT EQEMU_CUSTOM_PRNG_ENGINE STREQUAL "")
+		MESSAGE(STATUS "CUSTOM_PRNG_ENGINE and ADDITITVE_LFIB_PRNG both set, CUSTOM_PRNG_ENGINE ignored.")
+		SET(EQEMU_CUSTOM_PRNG_ENGINE "")
+	ENDIF()
+ENDIF()
+
+IF(EQEMU_SFMT19937)
+	ADD_DEFINITIONS(-DUSE_SFMT19937)
+	IF(NOT EQEMU_CUSTOM_PRNG_ENGINE STREQUAL "")
+		MESSAGE(STATUS "CUSTOM_PRNG_ENGINE and SFMT19937 both set, CUSTOM_PRNG_ENGINE ignored.")
+		SET(EQEMU_CUSTOM_PRNG_ENGINE "")
+	ENDIF()
+ENDIF()
+
+IF(NOT EQEMU_CUSTOM_PRNG_ENGINE STREQUAL "")
+	ADD_DEFINITIONS(-DUSE_CUSTOM_PRNG_ENGINE=${EQEMU_CUSTOM_PRNG_ENGINE})
+ENDIF()
+
+IF(EQEMU_BIASED_INT_DIST)
+	ADD_DEFINITIONS(-DBIASED_INT_DIST)
+ENDIF()
+
 IF(EQEMU_COMMANDS_LOGGING)
 	ADD_DEFINITIONS(-DCOMMANDS_LOGGING)
 ENDIF(EQEMU_COMMANDS_LOGGING)

common/CMakeLists.txt

@@ -451,6 +451,7 @@ SET(repositories
 )
 
 SET(common_headers
+	additive_lagged_fibonacci_engine.h
 	any.h
 	base_packet.h
 	base_data.h

common/additive_lagged_fibonacci_engine.h

@@ -0,0 +1,147 @@
+/*	EQEMu: Everquest Server Emulator
+	Copyright (C) 2001-2021 EQEMu Development Team (http://eqemulator.net)
+
+	This program is free software; you can redistribute it and/or modify
+	it under the terms of the GNU General Public License as published by
+	the Free Software Foundation; version 2 of the License.
+
+	This program is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY except by those people which sell it, which
+	are required to give you total support for your newly bought product;
+	without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+	A PARTICULAR PURPOSE. See the GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with this program; if not, write to the Free Software
+	Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+*/
+
+#pragma once
+
+#include <cstdint>
+#include <limits>
+#include <type_traits>
+#include <algorithm>
+#include <iostream>
+
+/*
+ * This is an additive lagged fibonacci generator as seen in The Art of Computer Programming, Vol. 2
+ * This should roughly match the implementation that EQ's client uses and be compatible with our Random class
+ *
+ * EQ's rand looks like it was from an example implementation that as posted on pscode.com
+ *
+ * You might also want to consider defining BIASED_INT_DIST as well to more closely match EQ
+ */
+
+namespace EQ {
+	template<typename UIntType, size_t w, size_t j, size_t k>
+	class additive_lagged_fibonacci_engine {
+		static_assert(std::is_unsigned<UIntType>::value, "result_type must be an unsigned integral type");
+		static_assert(0u < j && j < k, "0 < j < k");
+		static_assert(0u < w && w <= std::numeric_limits<UIntType>::digits,
+			      "template argument substituting w out of bounds");
+
+	public:
+		using result_type = UIntType;
+		static constexpr size_t word_size = w;
+		static constexpr size_t short_lag = j;
+		static constexpr size_t long_lag = k;
+		static constexpr result_type default_seed = 19780503u; // default for subtract_with_carry_engine
+
+		additive_lagged_fibonacci_engine() : additive_lagged_fibonacci_engine(default_seed) {}
+
+		explicit additive_lagged_fibonacci_engine(result_type sd) { seed(sd); }
+
+		void seed(result_type seed = default_seed)
+		{
+			state1 = long_lag - long_lag;
+			state2 = long_lag - short_lag;
+			state[0] = static_cast<int>(seed) & ((1u << word_size) - 1);
+			state[1] = 1;
+			for (int i = 2; i < long_lag; ++i)
+				state[i] = (state[i - 1] + state[i - 2]) & ((1u << word_size) - 1);
+			return;
+			}
+			// TODO: seed via seed_seq
+
+			static constexpr result_type min() { return 0; }
+			static constexpr result_type max() { return ((1u << word_size) - 1) >> 6; }
+
+			void discard(unsigned long long z) {
+				for (; z != 0ULL; --z)
+					(*this)();
+			}
+
+			result_type operator()() {
+				result_type rand = (state[state1] + state[state2]) & ((1u << word_size) - 1);
+				state[state1] = rand;
+				if (++state1 == long_lag)
+					state1 = 0;
+				if (++state2 == long_lag)
+					state2 = 0;
+
+				return rand >> 6;
+			}
+
+		private:
+			result_type state1;
+			result_type state2;
+			result_type state[long_lag];
+
+		public:
+			template<typename UInt, size_t W, size_t J, size_t K>
+			friend bool operator==(const additive_lagged_fibonacci_engine<UInt, W, J, K> &x,
+					const additive_lagged_fibonacci_engine<UInt, W, J, K> &y)
+			{
+				return std::equal(x.state, x.state + long_lag, y.state) && x.state1 == y.state1 &&
+				       x.state2 == y.state2;
+			}
+
+			template<typename UInt, size_t W, size_t J, size_t K>
+			friend bool operator!=(const additive_lagged_fibonacci_engine<UInt, W, J, K> &x,
+					const additive_lagged_fibonacci_engine<UInt, W, J, K> &y)
+			{ return !(x == y); }
+
+			template<typename UInt, size_t W, size_t J, size_t K, typename CharT, typename Traits>
+			friend std::basic_ostream<CharT, Traits> &
+			operator<<(std::basic_istream<CharT, Traits> &os, additive_lagged_fibonacci_engine<UInt, W, J, K> &x)
+			{
+				using ios_base = typename std::basic_istream<CharT, Traits>::ios_base;
+
+				const typename ios_base::fmtflags flags = os.flags();
+				const CharT fill = os.fill();
+				const CharT space = os.widen(' ');
+				os.flags(ios_base::dec | ios_base::fixed | ios_base::left);
+				os.fill(space);
+
+				for (size_t i = 0; i < long_lag; ++i)
+					os << x.state[i] << space;
+				os << x.state1 << space << x.state2;
+
+				os.flags(flags);
+				os.fill(fill);
+				return os;
+			}
+
+			template<typename UInt, size_t W, size_t J, size_t K, typename CharT, typename Traits>
+			friend std::basic_istream<CharT, Traits> &
+			operator>>(std::basic_istream<CharT, Traits> &is, additive_lagged_fibonacci_engine<UInt, W, J, K> &x)
+			{
+				using ios_base = typename std::basic_istream<CharT, Traits>::ios_base;
+
+				const typename ios_base::fmtflags flags = is.flags();
+				is.flags(ios_base::dec | ios_base::skipws);
+
+				for (size_t i = 0; i < long_lag; ++i)
+					is >> x.state[i];
+				is >> x.state1;
+				is >> x.state2;
+
+				is.flags(flags);
+				return is;
+			}
+	};
+
+	using EQRand = additive_lagged_fibonacci_engine<uint32_t, 30, 24, 55>;
+};
+

common/random.h

@@ -1,5 +1,5 @@
 /*	EQEMu: Everquest Server Emulator
-	Copyright (C) 2001-2014 EQEMu Development Team (http://eqemulator.net)
+	Copyright (C) 2001-2021 EQEMu Development Team (http://eqemulator.net)
 
 	This program is free software; you can redistribute it and/or modify
 	it under the terms of the GNU General Public License as published by
@@ -25,10 +25,24 @@
 #include <iterator>
 #include <type_traits>
 
-/* This uses mt19937 seeded with the std::random_device
+#ifdef USE_SFMT19937
- * The idea is to have this be included as a member of another class
+// only GCC supports, so lets turn it off
- * so mocking out for testing is easier
+#ifndef __GNUC__
- * If you need to reseed random.Reseed()
+#undef USE_SFMT19937
+#endif
+#ifdef __clang__
+#undef USE_SFMT19937
+#endif
+#endif
+
+#ifdef USE_ADDITIVE_LFIB_PRNG
+#include "additive_lagged_fibonacci_engine.h"
+#elif defined(USE_SFMT19937)
+#include <ext/random>
+#endif
+
+/* This uses mt19937 (or other compatible engine) seeded with the std::random_device. The idea is to have this be
+ * included as a member of another class so mocking out for testing is easier If you need to reseed random.Reseed()
  * Eventually this should be derived from an abstract base class
  */
 
@@ -40,7 +54,12 @@ namespace EQ {
 		{
 			if (low > high)
 				std::swap(low, high);
+// EQ uses biased int distribution, so I guess we can support it :P
+#ifdef BIASED_INT_DIST
+			return low + m_gen() % (high - low + 1);
+#else
 			return int_dist(m_gen, int_param_t(low, high)); // [low, high]
+#endif
 		}
 
 		// AKA old MakeRandomFloat
@@ -98,11 +117,24 @@ namespace EQ {
 		}
 
 	private:
+#ifndef BIASED_INT_DIST
 		typedef std::uniform_int_distribution<int>::param_type int_param_t;
-		typedef std::uniform_real_distribution<double>::param_type real_param_t;
-		std::mt19937 m_gen;
 		std::uniform_int_distribution<int> int_dist;
+#endif
+		typedef std::uniform_real_distribution<double>::param_type real_param_t;
 		std::uniform_real_distribution<double> real_dist;
+// define USE_CUSTOM_PRNG_ENGINE to any supported random engine like:
+// #define USE_CUSTOM_PRNG_ENGINE std::default_random_engine
+#ifdef USE_ADDITIVE_LFIB_PRNG
+		EQRand
+#elif defined(USE_SFMT19937)
+		__gnu_cxx::sfmt19937
+#elif defined(USE_CUSTOM_PRNG_ENGINE)
+		USE_CUSTOM_PRNG_ENGINE
+#else
+		std::mt19937
+#endif
+		m_gen;
 	};
 }