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Ia32e-paging

Accessed-bit

Signature
(accessed-bit entry) → bit
Returns: bit — Type (unsigned-byte-p 1 bit).

Definitions and Theorems

Function: accessed-bit

(defun accessed-bit (entry)
  (declare (type (unsigned-byte 64) entry))
  (let ((__function__ 'accessed-bit))
    (declare (ignorable __function__))
    (ia32e-page-tablesbits->a entry)))

Theorem: return-type-of-accessed-bit

(defthm return-type-of-accessed-bit
  (b* ((bit (accessed-bit entry)))
    (unsigned-byte-p 1 bit))
  :rule-classes :rewrite)

Theorem: n01p-accessed-bit

(defthm n01p-accessed-bit
 (unsigned-byte-p 1 (accessed-bit val))
 :rule-classes
 (:rewrite
  (:type-prescription
      :corollary (natp (accessed-bit val))
      :hints
      (("Goal" :in-theory '(unsigned-byte-p integer-range-p natp))))
  (:linear
   :corollary (and (<= 0 (accessed-bit val))
                   (< (accessed-bit val) 2))
   :hints
   (("Goal"
        :in-theory '(unsigned-byte-p integer-range-p (:e expt)))))))