Data commit

Task/Non-decimal-radices-Convert/ACL2/non-decimal-radices-convert.acl2

@@ -0,0 +1,35 @@
+(defun digit-value (chr)
+   (cond ((and (char>= chr #\0)
+               (char<= chr #\9))
+          (- (char-code chr) (char-code #\0)))
+         ((and (char>= chr #\A)
+               (char<= chr #\Z))
+          (+ (- (char-code chr) (char-code #\A)) 10))
+         ((and (char>= chr #\a)
+               (char<= chr #\z))
+          (+ (- (char-code chr) (char-code #\a)) 10))))
+
+(defun value-digit (n)
+   (if (< n 10)
+       (code-char (+ n (char-code #\0)))
+       (code-char (+ (- n 10) (char-code #\A)))))
+
+(defun num-from-cs (cs base)
+   (if (endp cs)
+       0
+       (+ (digit-value (first cs))
+          (* base (num-from-cs (rest cs) base)))))
+
+(defun parse-num (str base)
+   (num-from-cs (reverse (coerce str 'list)) base))
+
+(include-book "arithmetic-3/top" :dir :system)
+
+(defun num-to-cs (num base)
+   (if (or (zp num) (zp base) (= base 1))
+       nil
+       (cons (value-digit (mod num base))
+             (num-to-cs (floor num base) base))))
+
+(defun show-num (num base)
+   (coerce (reverse (num-to-cs num base)) 'string))