		Search-engine friendly clone of the ACL2 documentation.

Vl-expr-expandsizes

Vl-expandsizes-zeroextend

Safely zero-extend an already-sized, unsigned expression to finalwidth.

Signature
(vl-expandsizes-zeroextend x finalwidth ctx warnings) → (mv successp warnings new-x)
Arguments: x — An expression that we may need to zero-extend.
Guard (vl-expr-p x).; finalwidth — Width we want to expand x to. Must be at least as large as the final width of x.
Guard (natp finalwidth).; ctx — Context for warnings.
Guard (vl-context-p ctx).; warnings — Ordinary warnings accumulator.
Guard (vl-warninglist-p warnings).
Returns: successp — Type (booleanp successp).; warnings — Type (vl-warninglist-p warnings).; new-x — Type (vl-expr-p new-x).

Warning: this function should typically only be called by the expression-sizing transform.

If an extension is needed, we introduce an explicit concatenation, e.g., if we are expanding foo from 3 to 7 bits, we produce a new expression like { 4'b0, foo }. When no extension is needed, we just return x unchanged.

Definitions and Theorems

Function: vl-expandsizes-zeroextend

(defun vl-expandsizes-zeroextend (x finalwidth ctx warnings)
 (declare (xargs :guard (and (vl-expr-p x)
                             (natp finalwidth)
                             (vl-context-p ctx)
                             (vl-warninglist-p warnings))))
 (declare (xargs :guard (and (vl-expr->finalwidth x)
                             (eq (vl-expr->finaltype x)
                                 :vl-unsigned))))
 (let ((__function__ 'vl-expandsizes-zeroextend))
  (declare (ignorable __function__))
  (b*
   ((x (vl-expr-fix x))
    (ctx (vl-context-fix ctx))
    (finalwidth (lnfix finalwidth))
    (x.finalwidth (lnfix (vl-expr->finalwidth x)))
    ((when (> x.finalwidth finalwidth))
     (mv
      nil
      (fatal
       :type :vl-programming-error
       :msg
       "~a0: trying to zero-extend ~a1, which has width ~x2, ~
                         to ~x3 bits??? Serious bug in our sizing code."
       :args (list ctx x x.finalwidth finalwidth))
      x))
    ((when (eql x.finalwidth finalwidth))
     (mv t (ok) x))
    (pad-width (- finalwidth x.finalwidth))
    (zero-guts (make-vl-constint :value 0
                                 :origwidth pad-width
                                 :origtype :vl-unsigned
                                 :wasunsized nil))
    (zero-atom (make-vl-atom :guts zero-guts
                             :finalwidth pad-width
                             :finaltype :vl-unsigned))
    (atts (acons (hons-copy "VL_ZERO_EXTENSION")
                 nil nil))
    (concat (make-vl-nonatom :op :vl-concat
                             :args (list zero-atom x)
                             :finalwidth finalwidth
                             :finaltype :vl-unsigned
                             :atts atts)))
   (mv t (ok) concat))))

Theorem: booleanp-of-vl-expandsizes-zeroextend.successp

(defthm booleanp-of-vl-expandsizes-zeroextend.successp
  (b* (((mv ?successp ?warnings ?new-x)
        (vl-expandsizes-zeroextend x finalwidth ctx warnings)))
    (booleanp successp))
  :rule-classes :type-prescription)

Theorem: vl-warninglist-p-of-vl-expandsizes-zeroextend.warnings

(defthm vl-warninglist-p-of-vl-expandsizes-zeroextend.warnings
  (b* (((mv ?successp ?warnings ?new-x)
        (vl-expandsizes-zeroextend x finalwidth ctx warnings)))
    (vl-warninglist-p warnings))
  :rule-classes :rewrite)

Theorem: vl-expr-p-of-vl-expandsizes-zeroextend.new-x

(defthm vl-expr-p-of-vl-expandsizes-zeroextend.new-x
  (b* (((mv ?successp ?warnings ?new-x)
        (vl-expandsizes-zeroextend x finalwidth ctx warnings)))
    (vl-expr-p new-x))
  :rule-classes :rewrite)

Theorem: warning-irrelevance-of-vl-expandsizes-zeroextend

(defthm warning-irrelevance-of-vl-expandsizes-zeroextend
  (let ((ret1 (vl-expandsizes-zeroextend x finalwidth ctx warnings))
        (ret2 (vl-expandsizes-zeroextend x finalwidth nil nil)))
    (implies (syntaxp (not (and (equal ctx ''nil)
                                (equal warnings ''nil))))
             (and (equal (mv-nth 0 ret1) (mv-nth 0 ret2))
                  (equal (mv-nth 2 ret1)
                         (mv-nth 2 ret2))))))

Theorem: vl-expr->finalwidth-of-vl-expandsizes-zeroextend

(defthm vl-expr->finalwidth-of-vl-expandsizes-zeroextend
 (implies
  (and
      (mv-nth 0
              (vl-expandsizes-zeroextend x finalwidth ctx warnings))
      (force (vl-expr->finalwidth x))
      (force (equal (vl-expr->finaltype x)
                    :vl-unsigned)))
  (equal
   (vl-expr->finalwidth
     (mv-nth 2
             (vl-expandsizes-zeroextend x finalwidth ctx warnings)))
   (nfix finalwidth))))

Theorem: no-change-loser-of-vl-expandsizes-zeroextend

(defthm no-change-loser-of-vl-expandsizes-zeroextend
  (let ((ret (vl-expandsizes-zeroextend x finalwidth ctx warnings)))
    (implies (not (mv-nth 0 ret))
             (equal (mv-nth 2 ret)
                    (vl-expr-fix x)))))

Theorem: vl-expr->finaltype-of-vl-expandsizes-zeroextend

(defthm vl-expr->finaltype-of-vl-expandsizes-zeroextend
  (let ((ret (vl-expandsizes-zeroextend x finalwidth ctx warnings)))
    (implies (and (mv-nth 0 ret)
                  (force (vl-expr->finalwidth x))
                  (force (equal (vl-expr->finaltype x)
                                :vl-unsigned)))
             (equal (vl-expr->finaltype (mv-nth 2 ret))
                    :vl-unsigned))))

Theorem: vl-expr-welltyped-p-of-vl-expandsizes-zeroextend

(defthm vl-expr-welltyped-p-of-vl-expandsizes-zeroextend
  (let ((ret (vl-expandsizes-zeroextend x finalwidth ctx warnings)))
    (implies (and (mv-nth 0 ret)
                  (force (vl-expr-welltyped-p x))
                  (force (vl-expr->finalwidth x))
                  (force (equal (vl-expr->finaltype x)
                                :vl-unsigned)))
             (vl-expr-welltyped-p (mv-nth 2 ret)))))

Theorem: vl-expandsizes-zeroextend-of-vl-expr-fix-x

(defthm vl-expandsizes-zeroextend-of-vl-expr-fix-x
  (equal (vl-expandsizes-zeroextend (vl-expr-fix x)
                                    finalwidth ctx warnings)
         (vl-expandsizes-zeroextend x finalwidth ctx warnings)))

Theorem: vl-expandsizes-zeroextend-vl-expr-equiv-congruence-on-x

(defthm vl-expandsizes-zeroextend-vl-expr-equiv-congruence-on-x
 (implies
  (vl-expr-equiv x x-equiv)
  (equal
       (vl-expandsizes-zeroextend x finalwidth ctx warnings)
       (vl-expandsizes-zeroextend x-equiv finalwidth ctx warnings)))
 :rule-classes :congruence)

Theorem: vl-expandsizes-zeroextend-of-nfix-finalwidth

(defthm vl-expandsizes-zeroextend-of-nfix-finalwidth
  (equal (vl-expandsizes-zeroextend x (nfix finalwidth)
                                    ctx warnings)
         (vl-expandsizes-zeroextend x finalwidth ctx warnings)))

Theorem: vl-expandsizes-zeroextend-nat-equiv-congruence-on-finalwidth

(defthm vl-expandsizes-zeroextend-nat-equiv-congruence-on-finalwidth
 (implies
  (acl2::nat-equiv finalwidth finalwidth-equiv)
  (equal
       (vl-expandsizes-zeroextend x finalwidth ctx warnings)
       (vl-expandsizes-zeroextend x finalwidth-equiv ctx warnings)))
 :rule-classes :congruence)

Theorem: vl-expandsizes-zeroextend-of-vl-context-fix-ctx

(defthm vl-expandsizes-zeroextend-of-vl-context-fix-ctx
 (equal (vl-expandsizes-zeroextend x finalwidth (vl-context-fix ctx)
                                   warnings)
        (vl-expandsizes-zeroextend x finalwidth ctx warnings)))

Theorem: vl-expandsizes-zeroextend-vl-context-equiv-congruence-on-ctx

(defthm vl-expandsizes-zeroextend-vl-context-equiv-congruence-on-ctx
 (implies
  (vl-context-equiv ctx ctx-equiv)
  (equal
       (vl-expandsizes-zeroextend x finalwidth ctx warnings)
       (vl-expandsizes-zeroextend x finalwidth ctx-equiv warnings)))
 :rule-classes :congruence)

Theorem: vl-expandsizes-zeroextend-of-vl-warninglist-fix-warnings

(defthm vl-expandsizes-zeroextend-of-vl-warninglist-fix-warnings
  (equal
       (vl-expandsizes-zeroextend x finalwidth
                                  ctx (vl-warninglist-fix warnings))
       (vl-expandsizes-zeroextend x finalwidth ctx warnings)))

Theorem: vl-expandsizes-zeroextend-vl-warninglist-equiv-congruence-on-warnings

(defthm
 vl-expandsizes-zeroextend-vl-warninglist-equiv-congruence-on-warnings
 (implies
  (vl-warninglist-equiv warnings warnings-equiv)
  (equal
       (vl-expandsizes-zeroextend x finalwidth ctx warnings)
       (vl-expandsizes-zeroextend x finalwidth ctx warnings-equiv)))
 :rule-classes :congruence)