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Implementation-environments

Ienv->char-size

The ACL2 integer value of CHAR_BIT [C17:5.2.4.2.1/1].

Signature
(ienv->char-size ienv) → size
Arguments: ienv — Guard (ienvp ienv).
Returns: size — Type (posp size).

This is the size, in bits, of (possibly unsigned or signed) char objects.

Definitions and Theorems

Function: ienv->char-size

(defun ienv->char-size (ienv)
  (declare (xargs :guard (ienvp ienv)))
  (uchar-format->size
       (char+short+int+long+llong+bool-format->uchar
            (ienv->char+short+int+long+llong+bool-format ienv))))

Theorem: posp-of-ienv->char-size

(defthm posp-of-ienv->char-size
  (b* ((size (ienv->char-size ienv)))
    (posp size))
  :rule-classes :rewrite)

Theorem: ienv->char-size-type-prescription

(defthm ienv->char-size-type-prescription
  (b* ((?size (ienv->char-size ienv)))
    (and (posp size) (> size 1)))
  :rule-classes :type-prescription)

Theorem: ienv->char-size-lower-bound

(defthm ienv->char-size-lower-bound
  (b* ((?size (ienv->char-size ienv)))
    (>= size 8))
  :rule-classes :linear)

Theorem: ienv->char-size-of-ienv-fix-ienv

(defthm ienv->char-size-of-ienv-fix-ienv
  (equal (ienv->char-size (ienv-fix ienv))
         (ienv->char-size ienv)))

Theorem: ienv->char-size-ienv-equiv-congruence-on-ienv

(defthm ienv->char-size-ienv-equiv-congruence-on-ienv
  (implies (ienv-equiv ienv ienv-equiv)
           (equal (ienv->char-size ienv)
                  (ienv->char-size ienv-equiv)))
  :rule-classes :congruence)