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Types

Integer-type-bits

Number of bits that forms a value of a C integer type.

Signature
(integer-type-bits type) → bits
Arguments: type — Guard (typep type).
Returns: bits — Type (posp bits).

Definitions and Theorems

Function: integer-type-bits

(defun integer-type-bits (type)
  (declare (xargs :guard (typep type)))
  (declare (xargs :guard (type-integerp type)))
  (case (type-kind type)
    ((:char :schar :uchar) (char-bits))
    ((:sshort :ushort) (short-bits))
    ((:sint :uint) (int-bits))
    ((:slong :ulong) (long-bits))
    ((:sllong :ullong) (llong-bits))
    (t (prog2$ (impossible) 1))))

Theorem: posp-of-integer-type-bits

(defthm posp-of-integer-type-bits
  (b* ((bits (integer-type-bits type)))
    (posp bits))
  :rule-classes :type-prescription)

Theorem: integer-type-bits-of-type-fix-type

(defthm integer-type-bits-of-type-fix-type
  (equal (integer-type-bits (type-fix type))
         (integer-type-bits type)))

Theorem: integer-type-bits-type-equiv-congruence-on-type

(defthm integer-type-bits-type-equiv-congruence-on-type
  (implies (type-equiv type type-equiv)
           (equal (integer-type-bits type)
                  (integer-type-bits type-equiv)))
  :rule-classes :congruence)