Access the |X86ISA|::|UNKNOWNBITS| field of a data-segment-descriptor-attributesbits bit structure.
(data-segment-descriptor-attributesbits->unknownbits x) → unknownbits
Function:
(defun data-segment-descriptor-attributesbits->unknownbits$inline (x) (declare (xargs :guard (data-segment-descriptor-attributesbits-p x))) (mbe :logic (let ((x (data-segment-descriptor-attributesbits-fix x))) (part-select x :low 12 :width 4)) :exec (the (unsigned-byte 4) (logand (the (unsigned-byte 4) 15) (the (unsigned-byte 4) (ash (the (unsigned-byte 16) x) -12))))))
Theorem:
(defthm 4bits-p-of-data-segment-descriptor-attributesbits->unknownbits (b* ((unknownbits (data-segment-descriptor-attributesbits->unknownbits$inline x))) (4bits-p unknownbits)) :rule-classes :rewrite)
Theorem:
(defthm data-segment-descriptor-attributesbits->unknownbits$inline-of-data-segment-descriptor-attributesbits-fix-x (equal (data-segment-descriptor-attributesbits->unknownbits$inline (data-segment-descriptor-attributesbits-fix x)) (data-segment-descriptor-attributesbits->unknownbits$inline x)))
Theorem:
(defthm data-segment-descriptor-attributesbits->unknownbits$inline-data-segment-descriptor-attributesbits-equiv-congruence-on-x (implies (data-segment-descriptor-attributesbits-equiv x x-equiv) (equal (data-segment-descriptor-attributesbits->unknownbits$inline x) (data-segment-descriptor-attributesbits->unknownbits$inline x-equiv))) :rule-classes :congruence)
Theorem:
(defthm data-segment-descriptor-attributesbits->unknownbits-of-data-segment-descriptor-attributesbits (equal (data-segment-descriptor-attributesbits->unknownbits (data-segment-descriptor-attributesbits a w e msb-of-type s dpl p avl l d/b g unknownbits)) (4bits-fix unknownbits)))
Theorem:
(defthm data-segment-descriptor-attributesbits->unknownbits-of-write-with-mask (implies (and (fty::bitstruct-read-over-write-hyps x data-segment-descriptor-attributesbits-equiv-under-mask) (data-segment-descriptor-attributesbits-equiv-under-mask x y fty::mask) (equal (logand (lognot fty::mask) 61440) 0)) (equal (data-segment-descriptor-attributesbits->unknownbits x) (data-segment-descriptor-attributesbits->unknownbits y))))