added a thread-safe and cross-plateform random number generator

git-svn-id: http://svn.code.sf.net/p/retroshare/code/trunk@3373 b45a01b8-16f6-495d-af2f-9b41ad6348cc

libretroshare/src/util/rsrandom.cc

@@ -0,0 +1,73 @@
+#include <stdlib.h>
+#include "rsrandom.h"
+
+uint32_t RSRandom::index = 0 ;
+static bool auto_seed = RSRandom::seed(time(NULL)) ;
+std::vector<uint32_t> RSRandom::MT(RSRandom::N,0u) ;
+RsMutex RSRandom::rndMtx ;
+
+bool RSRandom::seed(uint32_t s) 
+{
+	RsStackMutex mtx(rndMtx) ;
+
+	MT.resize(N,0) ;	// because MT might not be already resized
+
+	uint32_t j ;
+	MT[0]= s & 0xffffffffUL;
+	for (j=1; j<N; j++) 
+		MT[j] = (1812433253UL * (MT[j-1] ^ (MT[j-1] >> 30)) + j) & 0xffffffffUL ;
+
+	return true ;
+}
+
+void RSRandom::locked_next_state() 
+{
+	for(uint32_t i=0;i<N;++i)
+	{
+		uint32_t y = ((MT[i]) & UMASK) | ((MT[(i+1)%(int)N]) & LMASK) ;
+
+		MT[i] = MT[(i + M) % (int)N] ^ (y >> 1) ;
+
+		if((y & 1) == 1) 
+			MT[i] = MT[i] ^ 0x9908b0df ;
+	}
+	index = 0 ;
+}
+
+uint32_t RSRandom::random_u32() 
+{
+	uint32_t y;
+
+	{
+		RsStackMutex mtx(rndMtx) ;
+
+		y = MT[index++] ;
+
+		if(index == N)
+			locked_next_state();
+	}
+
+	// Tempering
+	y ^= (y >> 11);
+	y ^= (y << 7 ) & 0x9d2c5680UL;
+	y ^= (y << 15) & 0xefc60000UL;
+	y ^= (y >> 18);
+
+	return y;
+}
+
+uint64_t RSRandom::random_u64() 
+{
+	return ((uint64_t)random_u32() << 32ul) + random_u32() ;
+}
+
+float RSRandom::random_f32() 
+{
+	return random_u32() / (float)(~(uint32_t)0) ;
+}
+
+double RSRandom::random_f64() 
+{
+	return random_u64() / (double)(~(uint64_t)0) ;
+}
+

libretroshare/src/util/rsrandom.h

@@ -0,0 +1,60 @@
+/****************************************************************
+ *  RetroShare is distributed under the following license:
+ *
+ *  Copyright (C) 2010 Cyril Soler <csoler@users.sourceforge.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; either version 2
+ *  of the License, or (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; 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., 51 Franklin Street, Fifth Floor, 
+ *  Boston, MA  02110-1301, USA.
+ ****************************************************************/
+ 
+#pragma once
+
+// RSRandom contains a random number generator that is
+// - thread safe
+// - system independant
+// - fast
+// - cryptographically safe
+//
+// The implementation is adapted from the Mersenne Twister page of Wikipedia.
+//
+// 		http://en.wikipedia.org/wiki/Mersenne_twister
+
+#include <vector>
+#include <util/rsthreads.h>
+
+class RSRandom
+{
+	public:
+		static uint32_t random_u32() ;
+		static uint64_t random_u64() ;
+		static float 	 random_f32() ;
+		static double	 random_f64() ;
+
+		static bool     seed(uint32_t s) ;
+
+	private:
+		static RsMutex rndMtx ;
+
+		static const uint32_t N = 624;
+		static const uint32_t M = 397;
+
+		static const uint32_t MATRIX_A 	= 0x9908b0dfUL;
+		static const uint32_t UMASK 		= 0x80000000UL;
+		static const uint32_t LMASK 		= 0x7fffffffUL;
+
+		static void locked_next_state() ;
+		static uint32_t index ;
+		static std::vector<uint32_t> MT ;
+};