wow. that was easy: git mv core nucleus

[feisty_meow.git] / nucleus / library / mathematics / chaos.h

diff --git a/nucleus/library/mathematics/chaos.h b/nucleus/library/mathematics/chaos.h
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+++ b/nucleus/library/mathematics/chaos.h
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+#ifndef CHAOS_CLASS
+#define CHAOS_CLASS
+
+//////////////
+// Name   : chaos
+// Author : Chris Koeritz
+//////////////
+// Copyright (c) 1991-$now By Author.  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:
+//     http://www.gnu.org/licenses/gpl.html
+// Please send updates for this code to: fred@gruntose.com -- Thanks, fred.
+//////////////
+
+#include <basis/definitions.h>
+#include <basis/enhance_cpp.h>
+#include <basis/environment.h>
+#include <timely/time_stamp.h>
+
+//#define DEBUG_CHAOS
+  // uncomment for noisy logging.
+
+#ifdef DEBUG_CHAOS
+  #include <stdio.h>
+#endif
+#include <stdlib.h>
+#include <time.h>
+#ifdef __UNIX__
+  #include <sys/times.h>
+#endif
+
+namespace mathematics {
+
+// gets a 32 bit integer from the 15 bit random generator.  it's 15 bit because
+// rand() only generates numbers up to the MAX_RAND, which in the visual c++
+// case is limited to 0x7FFF.  so, we let the first random number generated
+// serve as the upper two bytes and we shift another one over a bit to cover
+// the whole range of the third and fourth byte, except for that last bit, 
+// which is added in as a binary random value.
+#define GET_32_BIT_RAND_YO \
+  basis::un_int ranval = (basis::un_int(rand()) << 16) + (basis::un_int(rand()) << 1) \
+       + (basis::un_int(rand()) % 2)
+
+//! a platform-independent way to acquire random numbers in a specific range.
+/*!
+  This object also re-seeds the underlying system's random seed when retrain()
+  is invoked.
+*/
+
+class chaos : public virtual basis::nameable
+{
+public:
+  chaos() { retrain(); }
+  virtual ~chaos() {}
+
+  DEFINE_CLASS_NAME("chaos");
+
+  void retrain()
+    //!< Scrambles the OS's random seed and then provides pseudo-random values.
+  {
+    static unsigned int __flaxen = 0;
+    if (!__flaxen) {
+      time_t time_num;
+      time(&time_num);
+      // "t" is an ugly pointer into system data that contains the time nicely
+      // broken up into segments.  the pointer cannot be freed!
+      tm *t = localtime(&time_num);
+      int add_in_milliseconds = basis::environment::system_uptime();
+      // create a good random number seed from the time.
+#ifdef DEBUG_CHAOS
+      printf("day %d hour %d min %d sec %d", (int)t->tm_mday, (int)t->tm_hour,
+          (int)t->tm_min, (int)t->tm_sec);
+#endif
+      // we really don't care very much about the small chance of this being
+      // initialized to zero again.  the chance of that happening more than once
+      // should be pretty astronomical.
+      __flaxen = (t->tm_sec + 60 * t->tm_mday + 60 * 31 * t->tm_hour
+        + 24 * 60 * 31 * t->tm_min) ^ add_in_milliseconds;
+      // initialize random generator.
+      srand(int(__flaxen));
+    }
+  }
+
+  // Keep in mind for the inclusive and exclusive functions that a range which
+  // is too large might not be dealt with well.  This is because the random
+  // functions provided by the O.S. may not support the full range of integers.
+
+  int inclusive(int low, int high) const
+    //!< Returns a pseudo-random number r, such that "low" <= r <= "high".
+  {
+    if (high < low) return low;
+    unsigned int range = high - low + 1;
+    GET_32_BIT_RAND_YO;
+    int adjusted = ranval % range + low;
+    return adjusted;
+  }
+
+  int exclusive(int low, int high) const
+    //!< Returns a pseudo-random number r, such that "low" < r < "high".
+  {
+    if (high < low) return low + 1;
+    unsigned int range = high - low - 1;
+    GET_32_BIT_RAND_YO;
+    int adjusted = ranval % range + low + 1;
+    return adjusted;
+  }
+
+};
+
+} //namespace.
+
+#endif
+