diff -r c55016431358 -r 0a7b44b10206 symport/e32/euser/maths/um_rand.cpp --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/symport/e32/euser/maths/um_rand.cpp Thu Jun 25 15:59:54 2009 +0100 @@ -0,0 +1,64 @@ +// Copyright (c) 1995-2009 Nokia Corporation and/or its subsidiary(-ies). +// All rights reserved. +// This component and the accompanying materials are made available +// under the terms of the License "Symbian Foundation License v1.0" +// which accompanies this distribution, and is available +// at the URL "http://www.symbianfoundation.org/legal/sfl-v10.html". +// +// Initial Contributors: +// Nokia Corporation - initial contribution. +// +// Contributors: +// +// Description: +// e32\euser\maths\um_rand.cpp +// +// + +#include "um_std.h" + + + + +EXPORT_C TInt Math::Rand(TInt64 &aSeed) +/** +Generates a stream of uniformly distributed pseudo-random integers +in the range, 0 to KMaxTInt. + +For each stream of pseudo-random numbers you wish to generate, you should +pass the reference to the same 64-bit seed on each call to this function. +You should not change the seed between calls. + +@param aSeed A reference to a 64-bit seed, which is updated + as a result of the call. + +@return The next pseudo-random number in the sequence. +*/ + { + + aSeed*=214013; + aSeed+=2531011; + return(((TInt)(aSeed>>16))&0x7fffffff); + } + + + + +EXPORT_C TReal Math::FRand(TInt64& aSeed) __SOFTFP +/** +Generates a stream of uniformly distributed pseudo-random real numbers +in the range, 0 to 1. + +@param aSeed A reference to a 64-bit seed, which is updated + as a result of the call. + +@return The next pseudo-random number in the sequence. +*/ + { + TUint low = (TUint)Math::Rand(aSeed); + TUint high = (TUint)Math::Rand(aSeed)&0x7FFFFFFF; // make sure TInt64 is positive + TRealX f((static_cast(high) << 32) | low); // construct TRealX 0<=f<2^63 + if (f.iExp) + f.iExp-=63; // Scale f to range 0<=f<1 + return(TReal(f)); + }