Engine directory for ticket #1

Engine/source/math/mRandom.cpp

@@ -0,0 +1,171 @@
+//-----------------------------------------------------------------------------
+// Copyright (c) 2012 GarageGames, LLC
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to
+// deal in the Software without restriction, including without limitation the
+// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+// sell copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+// IN THE SOFTWARE.
+//-----------------------------------------------------------------------------
+
+#include "platform/platform.h"
+#include "math/mRandom.h"
+#include "core/util/journal/journal.h"
+
+MRandomLCG gRandGen;
+U32 gRandGenSeed = 1376312589;
+
+void MRandomLCG::setGlobalRandSeed(U32 seed)
+{
+	if (Journal::IsPlaying())
+		Journal::Read(&gRandGenSeed);
+	else
+	{
+		gRandGenSeed = seed;
+		if (Journal::IsRecording())
+			Journal::Write(gRandGenSeed);
+	}
+
+	//now actually set the seed
+	gRandGen.setSeed(gRandGenSeed);
+}
+
+static U32 msSeed = 1376312589;
+
+inline U32 generateSeed()
+{
+   // A very, VERY crude LCG but good enough to generate
+   // a nice range of seed values
+   msSeed = (msSeed * 0x015a4e35L) + 1;
+   msSeed = (msSeed>>16)&0x7fff;
+   return (msSeed);
+}
+
+//--------------------------------------
+void MRandomGenerator::setSeed()
+{
+   setSeed(generateSeed());
+}
+
+
+//--------------------------------------
+const S32 MRandomLCG::msQuotient  = S32_MAX / 16807L;
+const S32 MRandomLCG::msRemainder = S32_MAX % 16807L;
+
+
+//--------------------------------------
+MRandomLCG::MRandomLCG()
+{
+   setSeed(generateSeed());
+}
+
+MRandomLCG::MRandomLCG(S32 s)
+{
+   setSeed(s);
+}
+
+
+//--------------------------------------
+void MRandomLCG::setSeed(S32 s)
+{
+   mSeed = s;
+}
+
+
+//--------------------------------------
+U32 MRandomLCG::randI()
+{
+   if ( mSeed <= msQuotient )
+      mSeed = (mSeed * 16807L) % S32_MAX;
+   else
+   {
+      S32 high_part = mSeed / msQuotient;
+      S32 low_part  = mSeed % msQuotient;
+
+      S32 test = (16807L * low_part) - (msRemainder * high_part);
+
+      if ( test > 0 )
+         mSeed = test;
+      else
+         mSeed = test + S32_MAX;
+
+   }
+   return mSeed;
+}
+
+
+
+//--------------------------------------
+MRandomR250::MRandomR250()
+{
+   setSeed(generateSeed());
+}
+
+MRandomR250::MRandomR250(S32 s)
+{
+   setSeed(s);
+}
+
+
+//--------------------------------------
+void MRandomR250::setSeed(S32 s)
+{
+   mSeed = s;
+   MRandomLCG lcg( s );
+   mIndex = 0;
+
+   S32 j;
+   for (j = 0; j < 250; j++)        // fill r250 buffer with bit values
+      mBuffer[j] = lcg.randI();
+
+   for (j = 0; j < 250; j++)        // set some MSBs to 1
+      if ( lcg.randI() > 0x40000000L )
+         mBuffer[j] |= 0x80000000L;
+
+
+   U32 msb  = 0x80000000;           // turn on diagonal bit
+   U32 mask = 0xffffffff;           // turn off the leftmost bits
+
+   for (j = 0; j < 32; j++)
+   {
+      S32 k = 7 * j + 3;            // select a word to operate on
+      mBuffer[k] &= mask;           // turn off bits left of the diagonal
+      mBuffer[k] |= msb;            // turn on the diagonal bit
+      mask >>= 1;
+      msb  >>= 1;
+   }
+}
+
+
+//--------------------------------------
+U32 MRandomR250::randI()
+{
+   S32 j;
+
+   // wrap pointer around
+   if ( mIndex >= 147 ) j = mIndex - 147;
+   else                 j = mIndex + 103;
+
+   U32 new_rand = mBuffer[ mIndex ] ^ mBuffer[ j ];
+   mBuffer[ mIndex ] = new_rand;
+
+   // increment pointer for next time
+   if ( mIndex >= 249 ) mIndex = 0;
+   else                 mIndex++;
+
+   return new_rand >> 1;
+}
+
+