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49 lines
1.5 KiB
49 lines
1.5 KiB
5 years ago
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;;;; cl-rng.lisp
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(in-package #:cl-rng)
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(defun urandom (&key (limit 1.0) (precision 1) (transform nil))
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(let ((transform (or transform #'identity)))
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(with-open-file (rng "/dev/urandom" :element-type 'unsigned-byte)
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(assert (> precision 0))
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(if (= precision 1)
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(funcall transform (* limit (/ (read-byte rng) 255)))
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(let* ((val (apply '+ (loop for i from 0 below precision collect (read-byte rng))))
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(max (* precision 255))
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(frac (/ val max)))
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(values (* limit frac) frac))))))
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(defun %urandom-vector (range &rest params)
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(loop for x from 0 below (length range) collect
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(setf (aref range x) (apply 'urandom params))))
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(defun %urandom-list (range &rest params)
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(setf (car range) (apply 'urandom params))
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(unless (null (cdr range))
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(cons (car range) (apply '%urandom-list (cons (cdr range) params)))))
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(defun urandom-range (range &rest params)
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(if (listp range)
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(apply '%urandom-list (cons range params))
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(apply '%urandom-vector (cons range params))))
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(export 'urandom)
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(export 'urandom-range)
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;(defparameter *dice-results* (make-list 10))
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; (let ((num 0)
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; (max 10000)
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; (low 50))
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; (format t "~%Searching ~a values for >= ~a...~%" max low)
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; (loop for i from 0 below max do
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; (let ((value (apply '+ (urandom-range *dice-results* :limit 6 :transform (lambda (x) (1+ (floor x)))))))
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; (and (>= value low)
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; (incf num)
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; (format t " -> ~a: ~a~%" i value))))
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; (format t "Found ~a / ~a (~,8f %)~%" num max (* 100 (/ num max))))
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