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Representation-of-integer-operations

Minus-uchar-okp

Check if the unary minus of a value of type unsigned char is well-defined.

Definitions and Theorems

Function: minus-uchar-okp

(defun minus-uchar-okp (x)
  (declare (xargs :guard (and (ucharp x))))
  (minus-sint-okp (sint-from-uchar x)))

Theorem: booleanp-of-minus-uchar-okp

(defthm booleanp-of-minus-uchar-okp
  (booleanp (minus-uchar-okp x)))

Theorem: minus-uchar-okp-of-uchar-fix-x

(defthm minus-uchar-okp-of-uchar-fix-x
  (equal (minus-uchar-okp (uchar-fix x))
         (minus-uchar-okp x)))

Theorem: minus-uchar-okp-uchar-equiv-congruence-on-x

(defthm minus-uchar-okp-uchar-equiv-congruence-on-x
  (implies (uchar-equiv x x-equiv)
           (equal (minus-uchar-okp x)
                  (minus-uchar-okp x-equiv)))
  :rule-classes :congruence)