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    • Structures

    Vex->w

    Get the W field of vex-prefixes; cognizant of the two- or three-byte VEX prefixes form.

    Signature
    (vex->w vex-prefixes) → w
    Returns
    w — Type (unsigned-byte-p 1 w), given (vex-prefixes-byte0-p vex-prefixes).

    Definitions and Theorems

    Function: vex->w$inline

    (defun vex->w$inline (vex-prefixes)
      (declare (type (unsigned-byte 24) vex-prefixes))
      (declare (xargs :guard (vex-prefixes-byte0-p vex-prefixes)))
      (case (vex-prefixes->byte0 vex-prefixes)
        (196 (vex3-byte2->w (vex-prefixes->byte2 vex-prefixes)))
        (otherwise 0)))

    Theorem: return-type-of-vex->w

    (defthm return-type-of-vex->w
      (implies (vex-prefixes-byte0-p vex-prefixes)
               (b* ((w (vex->w$inline vex-prefixes)))
                 (unsigned-byte-p 1 w)))
      :rule-classes :rewrite)

    Theorem: if-not-vex3-byte0-then-vex-w=0

    (defthm if-not-vex3-byte0-then-vex-w=0
      (b* nil
        (implies (not (equal (vex-prefixes->byte0 vex-prefixes)
                             196))
                 (equal (vex->w vex-prefixes) 0))))