Access the |X86ISA|::|BASE15-0| field of a data-segment-descriptorbits bit structure.
(data-segment-descriptorbits->base15-0 x) → base15-0
Function:
(defun data-segment-descriptorbits->base15-0$inline (x) (declare (xargs :guard (data-segment-descriptorbits-p x))) (mbe :logic (let ((x (data-segment-descriptorbits-fix x))) (part-select x :low 16 :width 16)) :exec (the (unsigned-byte 16) (logand (the (unsigned-byte 16) 65535) (the (unsigned-byte 48) (ash (the (unsigned-byte 64) x) -16))))))
Theorem:
(defthm 16bits-p-of-data-segment-descriptorbits->base15-0 (b* ((base15-0 (data-segment-descriptorbits->base15-0$inline x))) (16bits-p base15-0)) :rule-classes :rewrite)
Theorem:
(defthm data-segment-descriptorbits->base15-0$inline-of-data-segment-descriptorbits-fix-x (equal (data-segment-descriptorbits->base15-0$inline (data-segment-descriptorbits-fix x)) (data-segment-descriptorbits->base15-0$inline x)))
Theorem:
(defthm data-segment-descriptorbits->base15-0$inline-data-segment-descriptorbits-equiv-congruence-on-x (implies (data-segment-descriptorbits-equiv x x-equiv) (equal (data-segment-descriptorbits->base15-0$inline x) (data-segment-descriptorbits->base15-0$inline x-equiv))) :rule-classes :congruence)
Theorem:
(defthm data-segment-descriptorbits->base15-0-of-data-segment-descriptorbits (equal (data-segment-descriptorbits->base15-0 (data-segment-descriptorbits limit15-0 base15-0 base23-16 a w e msb-of-type s dpl p limit19-16 avl l d/b g base31-24)) (16bits-fix base15-0)))
Theorem:
(defthm data-segment-descriptorbits->base15-0-of-write-with-mask (implies (and (fty::bitstruct-read-over-write-hyps x data-segment-descriptorbits-equiv-under-mask) (data-segment-descriptorbits-equiv-under-mask x y fty::mask) (equal (logand (lognot fty::mask) 4294901760) 0)) (equal (data-segment-descriptorbits->base15-0 x) (data-segment-descriptorbits->base15-0 y))))