1 files changed, 189 insertions, 0 deletions

diff --git a/noncore/games/sfcave-sdl/random.cpp b/noncore/games/sfcave-sdl/random.cpp
new file mode 100644
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+++ b/noncore/games/sfcave-sdl/random.cpp
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+/* -------------------------------------------------------------------------
+ * This is an ANSI C library for multi-stream random number generation.  
+ * The use of this library is recommended as a replacement for the ANSI C 
+ * rand() and srand() functions, particularly in simulation applications 
+ * where the statistical 'goodness' of the random number generator is 
+ * important.  The library supplies 256 streams of random numbers; use 
+ * SelectStream(s) to switch between streams indexed s = 0,1,...,255.
+ *
+ * The streams must be initialized.  The recommended way to do this is by
+ * using the function PlantSeeds(x) with the value of x used to initialize 
+ * the default stream and all other streams initialized automatically with
+ * values dependent on the value of x.  The following convention is used 
+ * to initialize the default stream:
+ *    if x > 0 then x is the state
+ *    if x < 0 then the state is obtained from the system clock
+ *    if x = 0 then the state is to be supplied interactively.
+ *
+ * The generator used in this library is a so-called 'Lehmer random number
+ * generator' which returns a pseudo-random number uniformly distributed
+ * 0.0 and 1.0.  The period is (m - 1) where m = 2,147,483,647 and the
+ * smallest and largest possible values are (1 / m) and 1 - (1 / m)
+ * respectively.  For more details see:
+ * 
+ *       "Random Number Generators: Good Ones Are Hard To Find"
+ *                   Steve Park and Keith Miller
+ *              Communications of the ACM, October 1988
+ *
+ * Name            : rngs.c  (Random Number Generation - Multiple Streams)
+ * Authors         : Steve Park & Dave Geyer
+ * Language        : ANSI C
+ * Latest Revision : 09-22-98
+ * ------------------------------------------------------------------------- 
+ */
+
+#include <stdio.h>
+#include <time.h>
+
+#define __RANDOM_CPP
+#include "random.h"
+
+#define MODULUS    2147483647 /* DON'T CHANGE THIS VALUE                  */
+#define MULTIPLIER 48271      /* DON'T CHANGE THIS VALUE                  */
+#define CHECK      399268537  /* DON'T CHANGE THIS VALUE                  */
+#define STREAMS    256        /* # of streams, DON'T CHANGE THIS VALUE    */
+#define A256       22925      /* jump multiplier, DON'T CHANGE THIS VALUE */
+#define DEFAULT    123456789  /* initial seed, use 0 < DEFAULT < MODULUS  */
+      
+static long seed[STREAMS] = {DEFAULT};  /* current state of each stream   */
+static int  stream        = 0;          /* stream index, 0 is the default */
+static int  initialized   = 0;          /* test for stream initialization */
+
+
+   double Random(void)
+/* ----------------------------------------------------------------
+ * Random returns a pseudo-random real number uniformly distributed 
+ * between 0.0 and 1.0. 
+ * ----------------------------------------------------------------
+ */
+{
+  const long Q = MODULUS / MULTIPLIER;
+  const long R = MODULUS % MULTIPLIER;
+        long t;
+
+  t = MULTIPLIER * (seed[stream] % Q) - R * (seed[stream] / Q);
+  if (t > 0) 
+    seed[stream] = t;
+  else 
+    seed[stream] = t + MODULUS;
+  return ((double) seed[stream] / MODULUS);
+}
+
+
+   void PlantSeeds(long x)
+/* ---------------------------------------------------------------------
+ * Use this function to set the state of all the random number generator 
+ * streams by "planting" a sequence of states (seeds), one per stream, 
+ * with all states dictated by the state of the default stream. 
+ * The sequence of planted states is separated one from the next by 
+ * 8,367,782 calls to Random().
+ * ---------------------------------------------------------------------
+ */
+{
+  const long Q = MODULUS / A256;
+  const long R = MODULUS % A256;
+        int  j;
+        int  s;
+
+  initialized = 1;
+  s = stream;                            /* remember the current stream */
+  SelectStream(0);                       /* change to stream 0          */
+  PutSeed(x);                            /* set seed[0]                 */
+  stream = s;                            /* reset the current stream    */
+  for (j = 1; j < STREAMS; j++) {
+    x = A256 * (seed[j - 1] % Q) - R * (seed[j - 1] / Q);
+    if (x > 0)
+      seed[j] = x;
+    else
+      seed[j] = x + MODULUS;
+   }
+}
+
+
+int nextInteger( int range,const char *file, int line )
+{
+    int val = (int)(Random( ) * range);
+        //printf( "nextInt() called from %s line %d - returning %d\n", file, line, val );
+
+    return val;
+    
+}
+   void PutSeed(long x)
+/* ---------------------------------------------------------------
+ * Use this function to set the state of the current random number 
+ * generator stream according to the following conventions:
+ *    if x > 0 then x is the state (unless too large)
+ *    if x < 0 then the state is obtained from the system clock
+ *    if x = 0 then the state is to be supplied interactively
+ * ---------------------------------------------------------------
+ */
+{
+  char ok = 0;
+
+  if (x > 0)
+    x = x % MODULUS;                       /* correct if x is too large  */
+  if (x < 0)                                 
+    x = ((unsigned long) time((time_t *) NULL)) % MODULUS;              
+  if (x == 0)                                
+    while (!ok) {
+      printf("\nEnter a positive integer seed (9 digits or less) >> ");
+      scanf("%ld", &x);
+      ok = (0 < x) && (x < MODULUS);
+      if (!ok)
+        printf("\nInput out of range ... try again\n");
+    }
+  seed[stream] = x;
+}
+
+
+   void GetSeed(long *x)
+/* ---------------------------------------------------------------
+ * Use this function to get the state of the current random number 
+ * generator stream.                                                   
+ * ---------------------------------------------------------------
+ */
+{
+  *x = seed[stream];
+}
+
+
+   void SelectStream(int index)
+/* ------------------------------------------------------------------
+ * Use this function to set the current random number generator
+ * stream -- that stream from which the next random number will come.
+ * ------------------------------------------------------------------
+ */
+{
+  stream = ((unsigned int) index) % STREAMS;
+  if ((initialized == 0) && (stream != 0))   /* protect against        */
+    PlantSeeds(DEFAULT);                     /* un-initialized streams */
+}
+
+
+   void TestRandom(void)
+/* ------------------------------------------------------------------
+ * Use this (optional) function to test for a correct implementation.
+ * ------------------------------------------------------------------    
+ */
+{
+  long   i;
+  long   x;
+  double u;
+  char   ok = 0;  
+
+  SelectStream(0);                  /* select the default stream */
+  PutSeed(1);                       /* and set the state to 1    */
+  for(i = 0; i < 10000; i++)
+    u = Random();
+  GetSeed(&x);                      /* get the new state value   */
+  ok = (x == CHECK);                /* and check for correctness */
+
+  SelectStream(1);                  /* select stream 1                 */ 
+  PlantSeeds(1);                    /* set the state of all streams    */
+  GetSeed(&x);                      /* get the state of stream 1       */
+  ok = ok && (x == A256);           /* x should be the jump multiplier */    
+  if (ok)
+    printf("\n The implementation of rngs.c is correct.\n\n");
+  else
+    printf("\n\a ERROR -- the implementation of rngs.c is not correct.\n\n");
+}