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Representation-of-integer-conversions

Schar-from-uint

Convert from type unsigned int to type signed char.

Signature
(schar-from-uint x) → result
Arguments: x — Guard (uintp x).
Returns: result — Type (scharp result).

Definitions and Theorems

Function: schar-from-uint

(defun schar-from-uint (x)
  (declare (xargs :guard (uintp x)))
  (declare (xargs :guard (schar-from-uint-okp x)))
  (let ((__function__ 'schar-from-uint))
    (declare (ignorable __function__))
    (schar-from-integer (integer-from-uint x))))

Theorem: scharp-of-schar-from-uint

(defthm scharp-of-schar-from-uint
  (b* ((result (schar-from-uint x)))
    (scharp result))
  :rule-classes :rewrite)

Theorem: schar-from-uint-of-uint-fix-x

(defthm schar-from-uint-of-uint-fix-x
  (equal (schar-from-uint (uint-fix x))
         (schar-from-uint x)))

Theorem: schar-from-uint-uint-equiv-congruence-on-x

(defthm schar-from-uint-uint-equiv-congruence-on-x
  (implies (uint-equiv x x-equiv)
           (equal (schar-from-uint x)
                  (schar-from-uint x-equiv)))
  :rule-classes :congruence)