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Npn4

Npn4-p

Recognizer for npn4 bit structures.

Signature
(npn4-p x) → *

Definitions and Theorems

Function: npn4-p

(defun npn4-p (x)
  (declare (xargs :guard t))
  (let ((__function__ 'npn4-p))
    (declare (ignorable __function__))
    (and (mbe :logic (unsigned-byte-p 27 x)
              :exec (and (natp x) (< x 134217728)))
         (perm4p (part-select x :low 21 :width 6)))))

Theorem: unsigned-byte-p-when-npn4-p

(defthm unsigned-byte-p-when-npn4-p
  (implies (npn4-p x)
           (unsigned-byte-p 27 x)))

Theorem: npn4-p-compound-recognizer

(defthm npn4-p-compound-recognizer
  (implies (npn4-p x) (natp x))
  :rule-classes :compound-recognizer)