added Mersenne Twister random-number-generator code

direct/src/showbase/Sources.pp

@@ -1,12 +1,12 @@
 #begin lib_target
   #define TARGET showbase
   #define LOCAL_LIBS \
-    directbase
+    directbase mersenne
   #define OTHER_LIBS \
     linmath:c putil:c panda:m express:c pandaexpress:m dtoolconfig dtool
 
   #define SOURCES \
-    showBase.cxx showBase.h
+    showBase.cxx showBase.h mersenne.cxx mersenne.h
 
   #define IGATESCAN all
 #end lib_target

direct/src/showbase/mersenne.cxx

@@ -0,0 +1,96 @@
+/* 
+   A C-program for MT19937, with initialization improved 2002/1/26.
+   Coded by Takuji Nishimura and Makoto Matsumoto.
+
+   Before using, initialize the state by using init_genrand(seed)  
+   or init_by_array(init_key, key_length).
+
+   Copyright (C) 1997 - 2002, Makoto Matsumoto and Takuji Nishimura,
+   All rights reserved.                          
+
+   Redistribution and use in source and binary forms, with or without
+   modification, are permitted provided that the following conditions
+   are met:
+
+     1. Redistributions of source code must retain the above copyright
+        notice, this list of conditions and the following disclaimer.
+
+     2. Redistributions in binary form must reproduce the above copyright
+        notice, this list of conditions and the following disclaimer in the
+        documentation and/or other materials provided with the distribution.
+
+     3. The names of its contributors may not be used to endorse or promote 
+        products derived from this software without specific prior written 
+        permission.
+
+   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+   A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+   CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+   EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+   PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+   PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+   LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+   NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+   SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+
+   Any feedback is very welcome.
+   http://www.math.keio.ac.jp/matumoto/emt.html
+   email: [email protected]
+*/
+
+#include "mersenne.h"
+#include <stdio.h>
+
+/* initializes mt[N] with a seed */
+Mersenne::
+Mersenne(unsigned long seed) {
+  mt[0]= seed & 0xffffffffUL;
+  for (mti=1; mti<N; mti++) {
+    mt[mti] = 
+      (1812433253UL * (mt[mti-1] ^ (mt[mti-1] >> 30)) + mti); 
+    /* See Knuth TAOCP Vol2. 3rd Ed. P.106 for multiplier. */
+    /* In the previous versions, MSBs of the seed affect   */
+    /* only MSBs of the array mt[].                        */
+    /* 2002/01/09 modified by Makoto Matsumoto             */
+    mt[mti] &= 0xffffffffUL;
+    /* for >32 bit machines */
+  }
+}
+
+/* generates a random number on [0,0x7fffffff]-interval */
+unsigned long Mersenne::
+get_uint31() {
+  unsigned long y;
+  static unsigned long mag01[2]={0x0UL, MATRIX_A};
+  /* mag01[x] = x * MATRIX_A  for x=0,1 */
+
+  if (mti >= N) { /* generate N words at one time */
+    int kk;
+
+    for (kk=0;kk<N-M;kk++) {
+      y = (mt[kk]&UPPER_MASK)|(mt[kk+1]&LOWER_MASK);
+      mt[kk] = mt[kk+M] ^ (y >> 1) ^ mag01[y & 0x1UL];
+    }
+    for (;kk<N-1;kk++) {
+      y = (mt[kk]&UPPER_MASK)|(mt[kk+1]&LOWER_MASK);
+      mt[kk] = mt[kk+(M-N)] ^ (y >> 1) ^ mag01[y & 0x1UL];
+    }
+    y = (mt[N-1]&UPPER_MASK)|(mt[0]&LOWER_MASK);
+    mt[N-1] = mt[M-1] ^ (y >> 1) ^ mag01[y & 0x1UL];
+
+    mti = 0;
+  }
+  
+  y = mt[mti++];
+
+  /* Tempering */
+  y ^= (y >> 11);
+  y ^= (y << 7) & 0x9d2c5680UL;
+  y ^= (y << 15) & 0xefc60000UL;
+  y ^= (y >> 18);
+
+  return y >> 1;
+}

direct/src/showbase/mersenne.h

@@ -0,0 +1,86 @@
+// Filename: mersenne.h
+// Created by:  darren (18Jul02)
+//
+////////////////////////////////////////////////////////////////////
+//
+// PANDA 3D SOFTWARE
+// Copyright (c) 2001, Disney Enterprises, Inc.  All rights reserved
+//
+// All use of this software is subject to the terms of the Panda 3d
+// Software license.  You should have received a copy of this license
+// along with this source code; you will also find a current copy of
+// the license at http://www.panda3d.org/license.txt .
+//
+// To contact the maintainers of this program write to
+// [email protected] .
+//
+////////////////////////////////////////////////////////////////////
+
+#ifndef MERSENNE_H
+#define MERSENNE_H
+
+/* 
+   A C-program for MT19937, with initialization improved 2002/1/26.
+   Coded by Takuji Nishimura and Makoto Matsumoto.
+
+   Before using, initialize the state by using init_genrand(seed)  
+   or init_by_array(init_key, key_length).
+
+   Copyright (C) 1997 - 2002, Makoto Matsumoto and Takuji Nishimura,
+   All rights reserved.                          
+
+   Redistribution and use in source and binary forms, with or without
+   modification, are permitted provided that the following conditions
+   are met:
+
+     1. Redistributions of source code must retain the above copyright
+        notice, this list of conditions and the following disclaimer.
+
+     2. Redistributions in binary form must reproduce the above copyright
+        notice, this list of conditions and the following disclaimer in the
+        documentation and/or other materials provided with the distribution.
+
+     3. The names of its contributors may not be used to endorse or promote 
+        products derived from this software without specific prior written 
+        permission.
+
+   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+   A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+   CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+   EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+   PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+   PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+   LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+   NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+   SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+
+   Any feedback is very welcome.
+   http://www.math.keio.ac.jp/matumoto/emt.html
+   email: [email protected]
+*/
+
+#include <directbase.h>
+
+class EXPCL_DIRECT Mersenne {
+PUBLISHED:
+  Mersenne(unsigned long seed);
+  unsigned long get_uint31();
+
+private:
+  enum {
+    // Period parameters
+    N = 624,
+    M = 397,
+    MATRIX_A = 0x9908b0dfUL,   // constant vector a
+    UPPER_MASK = 0x80000000UL, // most significant w-r bits
+    LOWER_MASK = 0x7fffffffUL, // least significant r bits
+  };
+
+  unsigned long mt[N]; // the array for the state vector
+  int mti; // mti==N+1 means mt[N] is not initialized
+};
+
+#endif