ported RandomNumbers

makefile

@@ -212,6 +212,7 @@ stage6:
 	$(VOCSTATIC) -sP ZlibReaders.Mod
 	$(VOCSTATIC) -sP ZlibWriters.Mod
 	$(VOCSTATIC) -sP Zip.Mod
+	$(VOCSTATIC) -sP RandomNumbers.Mod
 
 
 stage7:

src/lib/s3/RandomNumbers.Mod

@@ -0,0 +1,40 @@
+(* ETH Oberon, Copyright 2001 ETH Zuerich Institut fuer Computersysteme, ETH Zentrum, CH-8092 Zuerich.
+Refer to the "General ETH Oberon System Source License" contract available at: http://www.oberon.ethz.ch/ *)
+
+MODULE RandomNumbers;  (** portable *)
+(* Random Number Generator, page 12 *)
+IMPORT Math := oocOakMath, Oberon := Kernel, SYSTEM;
+
+VAR Z, t, d: LONGINT;
+
+(** Return a uniform random number r, with 0 < r < 1. *)
+
+PROCEDURE Uniform*(): REAL;
+CONST
+a = 16807;  m = 2147483647; 
+q = m DIV a;  r = m MOD a;
+VAR g: LONGINT;
+BEGIN
+  g := a*(Z MOD q) - r*(Z DIV q);
+  IF g > 0 THEN Z := g ELSE Z := g + m END;
+  RETURN SHORT(Z*1.0D0/m)  (* must compute this in double precision, e.g. (m-1)/m *)
+END Uniform;
+
+(** Return an exponentially distributed random number r. *)
+
+PROCEDURE Exp*(mu: REAL): REAL;
+BEGIN
+  RETURN -Math.ln(Uniform())/mu
+END Exp;
+
+(** Initialize the random number seed. *)
+
+PROCEDURE InitSeed*(seed: LONGINT);
+BEGIN
+  Z := seed
+END InitSeed;
+
+BEGIN
+  Oberon.GetClock(t, d);
+  Z := SYSTEM.VAL(LONGINT, SYSTEM.VAL(SET, t) / SYSTEM.VAL(SET, d))
+END RandomNumbers.  (* Copyright M. Reiser, 1992 *)