DESCRIPTION:
- NEXT-INTEGER returns the next randomly generated integer.
+ 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