		Search-engine friendly clone of the ACL2 documentation.

Code-segment-descriptorbits

Code-segment-descriptorbits->dpl

Access the |X86ISA|::|DPL| field of a code-segment-descriptorbits bit structure.

Signature
(code-segment-descriptorbits->dpl x) → dpl
Arguments: x — Guard (code-segment-descriptorbits-p x).
Returns: dpl — Type (2bits-p dpl).

Definitions and Theorems

Function: code-segment-descriptorbits->dpl$inline

(defun code-segment-descriptorbits->dpl$inline (x)
  (declare (xargs :guard (code-segment-descriptorbits-p x)))
  (mbe :logic
       (let ((x (code-segment-descriptorbits-fix x)))
         (part-select x :low 45 :width 2))
       :exec (the (unsigned-byte 2)
                  (logand (the (unsigned-byte 2) 3)
                          (the (unsigned-byte 19)
                               (ash (the (unsigned-byte 64) x)
                                    -45))))))

Theorem: 2bits-p-of-code-segment-descriptorbits->dpl

(defthm 2bits-p-of-code-segment-descriptorbits->dpl
  (b* ((dpl (code-segment-descriptorbits->dpl$inline x)))
    (2bits-p dpl))
  :rule-classes :rewrite)

Theorem: code-segment-descriptorbits->dpl$inline-of-code-segment-descriptorbits-fix-x

(defthm
 code-segment-descriptorbits->dpl$inline-of-code-segment-descriptorbits-fix-x
 (equal (code-segment-descriptorbits->dpl$inline
             (code-segment-descriptorbits-fix x))
        (code-segment-descriptorbits->dpl$inline x)))

Theorem: code-segment-descriptorbits->dpl$inline-code-segment-descriptorbits-equiv-congruence-on-x

(defthm
 code-segment-descriptorbits->dpl$inline-code-segment-descriptorbits-equiv-congruence-on-x
 (implies (code-segment-descriptorbits-equiv x x-equiv)
          (equal (code-segment-descriptorbits->dpl$inline x)
                 (code-segment-descriptorbits->dpl$inline x-equiv)))
 :rule-classes :congruence)

Theorem: code-segment-descriptorbits->dpl-of-code-segment-descriptorbits

(defthm
    code-segment-descriptorbits->dpl-of-code-segment-descriptorbits
  (equal (code-segment-descriptorbits->dpl
              (code-segment-descriptorbits
                   limit15-0
                   base15-0 base23-16 a r c msb-of-type
                   s dpl p limit19-16 avl l d g base31-24))
         (2bits-fix dpl)))

Theorem: code-segment-descriptorbits->dpl-of-write-with-mask

(defthm code-segment-descriptorbits->dpl-of-write-with-mask
 (implies
   (and (fty::bitstruct-read-over-write-hyps
             x
             code-segment-descriptorbits-equiv-under-mask)
        (code-segment-descriptorbits-equiv-under-mask x y fty::mask)
        (equal (logand (lognot fty::mask)
                       105553116266496)
               0))
   (equal (code-segment-descriptorbits->dpl x)
          (code-segment-descriptorbits->dpl y))))