Initial revision

1 files changed, 154 insertions, 0 deletions

diff --git a/isisd/topology/random.c b/isisd/topology/random.c
new file mode 100644
index 00000000..d4ef9950
--- /dev/null
+++ b/isisd/topology/random.c
@@ -0,0 +1,154 @@
+/*********************************************************************/
+/*                                                                   */
+/* current processor time in seconds                                 */
+/* difference between two calls is processor time spent by your code */
+/* needs: <sys/types.h>, <sys/times.h>                               */
+/* depends on compiler and OS                                        */
+/*                                                                   */
+/*********************************************************************/
+
+#include <sys/types.h>
+#include <sys/times.h>
+
+float timer()
+   { struct tms hold;
+
+        times(&hold);
+        return  (float)(hold.tms_utime) / 60.0;
+   }
+
+
+/*********************************************************************/
+/*                                                                   */
+/*            Family of random number generators                     */
+/*                                                                   */
+/*  Initialisation:                                                  */
+/*            void init_rand ( seed );                               */
+/*                 long seed     - any positive number               */
+/*                                 if seed<=0 init_rand takes time   */
+/*                                 from timer instead of seed        */
+/*                                                                   */
+/*  Whole number uniformly distributed on [0,n):                     */
+/*            long nrand (n);                                        */
+/*                 long n                                            */
+/*                                                                   */
+/*  Real number uniformly distributed on [0,1]                       */
+/*            double rand01();                                       */
+/*                                                                   */
+/*  Real number with Gauss(0,1) disitribution:                       */
+/*            double randg01();                                      */
+/*                                                                   */
+/*  Algorithm:                                                       */
+/*            x(n+1) = (x(n) * 5^13) mod 2^31                        */
+/*                                                                   */
+/*********************************************************************/
+
+unsigned long internal_seed;
+
+void init_rand ( init_seed )
+
+long init_seed;
+
+{ internal_seed = ( init_seed > 0 )
+                 ? (unsigned long) init_seed
+                 : (unsigned long) timer(); 
+                
+
+  /* only odd numbers are acceptable */
+  if ( internal_seed % 2 == 0 ) internal_seed --;
+}
+
+/*********************************************************************/
+/*                                                                   */
+/* Internal function  irand  may depend on OS and compiler           */
+/*                                                                   */
+/* irand assumption:                                                 */
+/* unsigned long i,j;                                                */
+/*   if i*j > max(unsigned long)                                     */
+/*           1. No overflow interruption                             */
+/*           2. i*j = i*j mod max(unsigned long)                     */
+/*                                                                   */
+/* This assumption is true for a lot of computers.                   */
+/* If your computer fails:                                           */
+/*   rename: irand <---> xrand                                       */
+/*                                                                   */
+/*********************************************************************/
+ 
+#define  A   1220703125
+#define  B   2147483647
+#define  BF  2147483647.
+
+static long irand ()
+
+{ internal_seed = ( internal_seed * A ) & B;
+  return (long) internal_seed ;
+}
+
+/*********************************************************************/
+/*                                                                   */
+/*              computer independent variant of  irand               */
+/*                                                                   */
+/*********************************************************************/
+
+
+#define T15  32768 
+#define T16  65536
+#define A1   37252
+#define A2   29589
+
+static long xrand()
+
+{ unsigned long is1, is2;
+
+  is1 = internal_seed / T15;
+  is2 = internal_seed % T15;
+
+  internal_seed = ( (((is2 * A1) + (is1 * A2))% T16 )* T15 + (is2 * A2) ) & B;
+  return (long) ( internal_seed ) ;
+}
+
+
+/*********************************************************************/
+
+
+double rand01()
+
+{ return  (double) irand() / BF ;
+}
+  
+/*********************************************************************/
+
+#define NK  12
+
+double randg01()
+
+{ int i;
+  double sum = 0;
+
+  for ( i = 0; i < NK; i++ ) sum += rand01();
+  return sum - 6.;
+
+  /* if   NK != 12  then you must return (12/NK)*sum - (NK/2) */
+}
+
+#undef NK
+     
+  
+/*********************************************************************/
+
+long nrand ( n )
+
+long n;
+
+{ return (long) ( rand01() * (double) n );
+}
+
+/*********************************************************************/
+
+#undef A
+#undef A1
+#undef A2
+#undef B
+#undef BF
+#undef T15
+#undef T16