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Execloader

Take-till-zero

Return all initial elements of bytes until a 0 element is encountered or the end of bytes is reached, whichever happens first.

Signature
(take-till-zero bytes) → bs
Arguments: bytes — Guard (byte-listp bytes).
Returns: bs — Type (byte-listp bs), given the guard.

Definitions and Theorems

Function: take-till-zero

(defun take-till-zero (bytes)
  (declare (xargs :guard (byte-listp bytes)))
  (let ((__function__ 'take-till-zero))
    (declare (ignorable __function__))
    (if (endp bytes)
        nil
      (if (equal (car bytes) 0)
          nil
        (cons (car bytes)
              (take-till-zero (cdr bytes)))))))

Theorem: byte-listp-of-take-till-zero

(defthm byte-listp-of-take-till-zero
  (implies (and (byte-listp bytes))
           (b* ((bs (take-till-zero bytes)))
             (byte-listp bs)))
  :rule-classes :rewrite)