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Structures

8bits

An 8-bit unsigned bitstruct type.

This is a bitstruct type introduced by defbitstruct, represented as a unsigned 8-bit integer.

This is an atomic/empty structure; it has no fields.

Definitions and Theorems

Function: 8bits-p

(defun 8bits-p (x)
  (declare (xargs :guard t))
  (let ((__function__ '8bits-p))
    (declare (ignorable __function__))
    (mbe :logic (unsigned-byte-p 8 x)
         :exec (and (natp x) (< x 256)))))

Theorem: 8bits-p-when-unsigned-byte-p

(defthm 8bits-p-when-unsigned-byte-p
  (implies (unsigned-byte-p 8 x)
           (8bits-p x)))

Theorem: unsigned-byte-p-when-8bits-p

(defthm unsigned-byte-p-when-8bits-p
  (implies (8bits-p x)
           (unsigned-byte-p 8 x)))

Theorem: 8bits-p-compound-recognizer

(defthm 8bits-p-compound-recognizer
  (implies (8bits-p x) (natp x))
  :rule-classes :compound-recognizer)

Function: 8bits-fix

(defun 8bits-fix (x)
  (declare (xargs :guard (8bits-p x)))
  (let ((__function__ '8bits-fix))
    (declare (ignorable __function__))
    (mbe :logic (loghead 8 x) :exec x)))

Theorem: 8bits-p-of-8bits-fix

(defthm 8bits-p-of-8bits-fix
  (b* ((fty::fixed (8bits-fix x)))
    (8bits-p fty::fixed))
  :rule-classes :rewrite)

Theorem: 8bits-fix-when-8bits-p

(defthm 8bits-fix-when-8bits-p
  (implies (8bits-p x)
           (equal (8bits-fix x) x)))

Function: 8bits-equiv$inline

(defun 8bits-equiv$inline (x y)
  (declare (xargs :guard (and (8bits-p x) (8bits-p y))))
  (equal (8bits-fix x) (8bits-fix y)))

Theorem: 8bits-equiv-is-an-equivalence

(defthm 8bits-equiv-is-an-equivalence
  (and (booleanp (8bits-equiv x y))
       (8bits-equiv x x)
       (implies (8bits-equiv x y)
                (8bits-equiv y x))
       (implies (and (8bits-equiv x y)
                     (8bits-equiv y z))
                (8bits-equiv x z)))
  :rule-classes (:equivalence))

Theorem: 8bits-equiv-implies-equal-8bits-fix-1

(defthm 8bits-equiv-implies-equal-8bits-fix-1
  (implies (8bits-equiv x x-equiv)
           (equal (8bits-fix x)
                  (8bits-fix x-equiv)))
  :rule-classes (:congruence))

Theorem: 8bits-fix-under-8bits-equiv

(defthm 8bits-fix-under-8bits-equiv
  (8bits-equiv (8bits-fix x) x)
  :rule-classes (:rewrite :rewrite-quoted-constant))

Subtopics

8bits-p: Recognizer for 8bits bit structures.
8bits-fix: Fixing function for 8bits bit structures.