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Prefixes

Prefixes->nxt

Access the |X86ISA|::|NXT| field of a prefixes bit structure.

Signature
(prefixes->nxt x) → nxt
Arguments: x — Guard (prefixes-p x).
Returns: nxt — Type (8bits-p nxt).

Definitions and Theorems

Function: prefixes->nxt$inline

(defun prefixes->nxt$inline (x)
  (declare (xargs :guard (prefixes-p x)))
  (mbe :logic
       (let ((x (prefixes-fix x)))
         (part-select x :low 44 :width 8))
       :exec (the (unsigned-byte 8)
                  (logand (the (unsigned-byte 8) 255)
                          (the (unsigned-byte 8)
                               (ash (the (unsigned-byte 52) x)
                                    -44))))))

Theorem: 8bits-p-of-prefixes->nxt

(defthm 8bits-p-of-prefixes->nxt
  (b* ((nxt (prefixes->nxt$inline x)))
    (8bits-p nxt))
  :rule-classes :rewrite)

Theorem: prefixes->nxt$inline-of-prefixes-fix-x

(defthm prefixes->nxt$inline-of-prefixes-fix-x
  (equal (prefixes->nxt$inline (prefixes-fix x))
         (prefixes->nxt$inline x)))

Theorem: prefixes->nxt$inline-prefixes-equiv-congruence-on-x

(defthm prefixes->nxt$inline-prefixes-equiv-congruence-on-x
  (implies (prefixes-equiv x x-equiv)
           (equal (prefixes->nxt$inline x)
                  (prefixes->nxt$inline x-equiv)))
  :rule-classes :congruence)

Theorem: prefixes->nxt-of-prefixes

(defthm prefixes->nxt-of-prefixes
  (equal (prefixes->nxt (prefixes num lck rep seg opr adr nxt))
         (8bits-fix nxt)))

Theorem: prefixes->nxt-of-write-with-mask

(defthm prefixes->nxt-of-write-with-mask
 (implies
  (and
   (fty::bitstruct-read-over-write-hyps x prefixes-equiv-under-mask)
   (prefixes-equiv-under-mask x y fty::mask)
   (equal (logand (lognot fty::mask)
                  4486007441326080)
          0))
  (equal (prefixes->nxt x)
         (prefixes->nxt y))))