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• Base64-impl

B64-encode-last-group

Encode the last group of (up to three) characters.

Signature

(b64-encode-last-group x) → (mv e1 e2 e3 e4)

Arguments

x — Guard (character-listp x).

Returns

e1 — Type (characterp e1).

e2 — Type (characterp e2).

e3 — Type (characterp e3).

e4 — Type (characterp e4).

Definitions and Theorems

Function: b64-encode-last-group

(defun b64-encode-last-group (x)
  (declare (xargs :guard (character-listp x)))
  (declare (xargs :guard (consp x)))
  (let ((acl2::__function__ 'b64-encode-last-group))
    (declare (ignorable acl2::__function__))
    (cond ((atom (cdr x))
           (b* (((mv c1 c2) (b64-enc1 (first x))))
             (mv c1 c2 #\= #\=)))
          ((atom (cddr x))
           (b* (((mv c1 c2 c3)
                 (b64-enc2 (first x) (second x))))
             (mv c1 c2 c3 #\=)))
          (t (b64-enc3 (first x)
                       (second x)
                       (third x))))))

Theorem: characterp-of-b64-encode-last-group.e1

(defthm characterp-of-b64-encode-last-group.e1
  (b* (((mv ?e1 ?e2 ?e3 ?e4)
        (b64-encode-last-group x)))
    (characterp e1))
  :rule-classes :type-prescription)

Theorem: characterp-of-b64-encode-last-group.e2

(defthm characterp-of-b64-encode-last-group.e2
  (b* (((mv ?e1 ?e2 ?e3 ?e4)
        (b64-encode-last-group x)))
    (characterp e2))
  :rule-classes :type-prescription)

Theorem: characterp-of-b64-encode-last-group.e3

(defthm characterp-of-b64-encode-last-group.e3
  (b* (((mv ?e1 ?e2 ?e3 ?e4)
        (b64-encode-last-group x)))
    (characterp e3))
  :rule-classes :type-prescription)

Theorem: characterp-of-b64-encode-last-group.e4

(defthm characterp-of-b64-encode-last-group.e4
  (b* (((mv ?e1 ?e2 ?e3 ?e4)
        (b64-encode-last-group x)))
    (characterp e4))
  :rule-classes :type-prescription)