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Modr/m

Modr/m->reg

Access the |X86ISA|::|REG| field of a modr/m bit structure.

Signature
(modr/m->reg x) → reg
Arguments: x — Guard (modr/m-p x).
Returns: reg — Type (3bits-p reg).

Definitions and Theorems

Function: modr/m->reg$inline

(defun modr/m->reg$inline (x)
 (declare (xargs :guard (modr/m-p x)))
 (mbe
     :logic
     (let ((x (modr/m-fix x)))
       (part-select x :low 3 :width 3))
     :exec (the (unsigned-byte 3)
                (logand (the (unsigned-byte 3) 7)
                        (the (unsigned-byte 5)
                             (ash (the (unsigned-byte 8) x) -3))))))

Theorem: 3bits-p-of-modr/m->reg

(defthm 3bits-p-of-modr/m->reg
  (b* ((reg (modr/m->reg$inline x)))
    (3bits-p reg))
  :rule-classes :rewrite)

Theorem: modr/m->reg$inline-of-modr/m-fix-x

(defthm modr/m->reg$inline-of-modr/m-fix-x
  (equal (modr/m->reg$inline (modr/m-fix x))
         (modr/m->reg$inline x)))

Theorem: modr/m->reg$inline-modr/m-equiv-congruence-on-x

(defthm modr/m->reg$inline-modr/m-equiv-congruence-on-x
  (implies (modr/m-equiv x x-equiv)
           (equal (modr/m->reg$inline x)
                  (modr/m->reg$inline x-equiv)))
  :rule-classes :congruence)

Theorem: modr/m->reg-of-modr/m

(defthm modr/m->reg-of-modr/m
  (equal (modr/m->reg (modr/m r/m reg mod))
         (3bits-fix reg)))

Theorem: modr/m->reg-of-write-with-mask

(defthm modr/m->reg-of-write-with-mask
 (implies
  (and
     (fty::bitstruct-read-over-write-hyps x modr/m-equiv-under-mask)
     (modr/m-equiv-under-mask x y fty::mask)
     (equal (logand (lognot fty::mask) 56)
            0))
  (equal (modr/m->reg x)
         (modr/m->reg y))))