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Vex-prefixes

Vex-prefixes->byte0

Access the |X86ISA|::|BYTE0| field of a vex-prefixes bit structure.

Signature
(vex-prefixes->byte0 x) → byte0
Arguments: x — Guard (vex-prefixes-p x).
Returns: byte0 — Type (8bits-p byte0).

Definitions and Theorems

Function: vex-prefixes->byte0$inline

(defun vex-prefixes->byte0$inline (x)
  (declare (xargs :guard (vex-prefixes-p x)))
  (mbe :logic
       (let ((x (vex-prefixes-fix x)))
         (part-select x :low 0 :width 8))
       :exec (the (unsigned-byte 8)
                  (logand (the (unsigned-byte 8) 255)
                          (the (unsigned-byte 24) x)))))

Theorem: 8bits-p-of-vex-prefixes->byte0

(defthm 8bits-p-of-vex-prefixes->byte0
  (b* ((byte0 (vex-prefixes->byte0$inline x)))
    (8bits-p byte0))
  :rule-classes :rewrite)

Theorem: vex-prefixes->byte0$inline-of-vex-prefixes-fix-x

(defthm vex-prefixes->byte0$inline-of-vex-prefixes-fix-x
  (equal (vex-prefixes->byte0$inline (vex-prefixes-fix x))
         (vex-prefixes->byte0$inline x)))

Theorem: vex-prefixes->byte0$inline-vex-prefixes-equiv-congruence-on-x

(defthm
      vex-prefixes->byte0$inline-vex-prefixes-equiv-congruence-on-x
  (implies (vex-prefixes-equiv x x-equiv)
           (equal (vex-prefixes->byte0$inline x)
                  (vex-prefixes->byte0$inline x-equiv)))
  :rule-classes :congruence)

Theorem: vex-prefixes->byte0-of-vex-prefixes

(defthm vex-prefixes->byte0-of-vex-prefixes
  (equal (vex-prefixes->byte0 (vex-prefixes byte0 byte1 byte2))
         (8bits-fix byte0)))

Theorem: vex-prefixes->byte0-of-write-with-mask

(defthm vex-prefixes->byte0-of-write-with-mask
  (implies (and (fty::bitstruct-read-over-write-hyps
                     x vex-prefixes-equiv-under-mask)
                (vex-prefixes-equiv-under-mask x y fty::mask)
                (equal (logand (lognot fty::mask) 255)
                       0))
           (equal (vex-prefixes->byte0 x)
                  (vex-prefixes->byte0 y))))