X-Git-Url: https://code.consxy.com/gitweb/gitweb.cgi?a=blobdiff_plain;f=src%2Fmain%2Frandom.lisp;h=4175073a429883e4aad326b30e45e04df1718df5;hb=008caa3;hp=6f500a979558a57fdd519d4323878ab43a5e8052;hpb=c34fdd7f3b9920b2feaf1dec70d2dd21ddbbadf2;p=clnl

diff --git a/src/main/random.lisp b/src/main/random.lisp
index 6f500a9..4175073 100644
--- a/src/main/random.lisp
+++ b/src/main/random.lisp
@@ -1,35 +1,111 @@
 (in-package #:clnl-random)
 
-; This is a wrapper around the very nice mersenne twister mt19937 to match
-; NetLogo's implementation that tries to match how java.util.Random works
- 
 (defun set-seed (n)
- (setf mt19937:*random-state* (mt19937::make-random-object :state (mt19937:init-random-state n))))
+ "SET-SEED => RESULT
+
+ARGUMENTS AND VALUES:
+
+  RESULT: undefined
+
+DESCRIPTION:
+
+  SET-SEED sets the seed on the RNG."
+ (setf mt19937:*random-state* (funcall
+                               (symbol-function (intern "MAKE-RANDOM-OBJECT" :mt19937))
+                               :state (mt19937:init-random-state n))))
 
 (defun next-int (n)
+ "NEXT-INT N => INT
+
+ARGUMENTS AND VALUES:
+
+  N: An integer representing the upper bound
+  INT: An integer
+
+DESCRIPTION:
+
+  NEXT-INT returns the next randomly generated integer.
+
+  It does so in a way that's in accordance with java.util.Random and
+  the MerseinneTwisterFast that's in NetLogo.  It also advances the
+  RNG and is bounded by N."
  (if
-  (= n (logand n (- n) ))
-  (ash (* n (ash (mt19937:random-chunk mt19937:*random-state*) -1) ) -31)
+  (= n (logand n (- n)))
+  (ash (* n (ash (mt19937:random-chunk mt19937:*random-state*) -1)) -31)
   (rem (ash (mt19937:random-chunk mt19937:*random-state*) -1) n)))
 
+(defun next-long (n)
+ "NEXT-LONG N => LONG
+
+ARGUMENTS AND VALUES:
+
+  N: A long representing the upper bound
+  LONG: A long
+
+DESCRIPTION:
+
+  NEXT-LONG returns the next randomly generated long.
+
+  It does so in a way that's in accordance with java.util.Random and
+  the MerseinneTwisterFast that's in NetLogo.  It also advances the
+  RNG and is bounded by N."
+ (flet
+  ((unsigned-to-signed (value size) ; We need this because MersenneTwisterFast
+    (if (logbitp (1- size) value) (dpb value (byte size 0) -1) value))
+   (signed-to-unsigned (value size) (ldb (byte size 0) value)))
+  (let
+   ((y (unsigned-to-signed (mt19937:random-chunk mt19937:*random-state*) 32))
+    (z (unsigned-to-signed (mt19937:random-chunk mt19937:*random-state*) 32)))
+   ;(mod (+ (ash y 32) z) n)))
+   (mod (signed-to-unsigned (ash (+ (ash y 32) z) -1) 63) n))))
+
 (defun next-double (&optional (n 1d0))
+ "NEXT-DOUBLE &optional N => DOUBLE
+
+ARGUMENTS AND VALUES:
+
+  N: A double representing the upper bound
+  DOUBLE: A double
+
+DESCRIPTION:
+
+  NEXT-DOUBLE returns the next randomly generated double.
+
+  It does so in a way that's in accordance with java.util.Random and
+  the MerseinneTwisterFast that's in NetLogo.  It also advances the
+  RNG and is bounded by N."
  (let
   ((y (mt19937:random-chunk mt19937:*random-state*))
    (z (mt19937:random-chunk mt19937:*random-state*)))
- (*
-  (/
-   (+ (ash (ash y -6) 27) (ash z -5))
-   (coerce (ash 1 53) 'double-float))
-  n)))
+  (*
+   (/
+    (+ (ash (ash y -6) 27) (ash z -5))
+    (coerce (ash 1 53) 'double-float))
+   n)))
 
 ; Oh, export world, you WILL be mine
 (defun export ()
+ "EXPORT => RANDOM-STATE
+
+ARGUMENTS AND VALUES:
+
+  RANDOM-STATE: A dump of the current random state
+
+DESCRIPTION:
+
+  EXPORT dumps out the random state to be export world ready.
+
+  When NetLogo dumps out the current state of the engine, the state of the
+  RNG also gets dumped out so that it can be reinitialized later.  This
+  accomplishes that.
+
+  This isn't really useful for regular use."
  (let
   ((state
     (map
      'list
      (lambda (x) (if (logbitp (1- 32) x) (dpb x (byte 32 0) -1) x))
-     (mt19937::random-state-state mt19937:*random-state*))))
+     (funcall (symbol-function (intern "RANDOM-STATE-STATE" :mt19937)) mt19937:*random-state*))))
   (format nil "0 ~A ~A ~A 0.0 false ~{~A~^ ~}"
    (first state) (second state) (third state)
    (nthcdr 3 state))))