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Vex-prefixes

Vex-prefixes->byte1

Access the |X86ISA|::|BYTE1| field of a vex-prefixes bit structure.

Signature
(vex-prefixes->byte1 x) → byte1
Arguments: x — Guard (vex-prefixes-p x).
Returns: byte1 — Type (8bits-p byte1).

Definitions and Theorems

Function: vex-prefixes->byte1$inline

(defun vex-prefixes->byte1$inline (x)
 (declare (xargs :guard (vex-prefixes-p x)))
 (mbe
    :logic
    (let ((x (vex-prefixes-fix x)))
      (part-select x :low 8 :width 8))
    :exec (the (unsigned-byte 8)
               (logand (the (unsigned-byte 8) 255)
                       (the (unsigned-byte 16)
                            (ash (the (unsigned-byte 24) x) -8))))))

Theorem: 8bits-p-of-vex-prefixes->byte1

(defthm 8bits-p-of-vex-prefixes->byte1
  (b* ((byte1 (vex-prefixes->byte1$inline x)))
    (8bits-p byte1))
  :rule-classes :rewrite)

Theorem: vex-prefixes->byte1$inline-of-vex-prefixes-fix-x

(defthm vex-prefixes->byte1$inline-of-vex-prefixes-fix-x
  (equal (vex-prefixes->byte1$inline (vex-prefixes-fix x))
         (vex-prefixes->byte1$inline x)))

Theorem: vex-prefixes->byte1$inline-vex-prefixes-equiv-congruence-on-x

(defthm
      vex-prefixes->byte1$inline-vex-prefixes-equiv-congruence-on-x
  (implies (vex-prefixes-equiv x x-equiv)
           (equal (vex-prefixes->byte1$inline x)
                  (vex-prefixes->byte1$inline x-equiv)))
  :rule-classes :congruence)

Theorem: vex-prefixes->byte1-of-vex-prefixes

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

Theorem: vex-prefixes->byte1-of-write-with-mask

(defthm vex-prefixes->byte1-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) 65280)
                       0))
           (equal (vex-prefixes->byte1 x)
                  (vex-prefixes->byte1 y))))