Lemmas about ash from the logops-lemmas book.
Theorem:
(defthm ash-0 (implies (zip i) (equal (ash i count) 0)))
Theorem:
(defthm unsigned-byte-p-ash (implies (and (unsigned-byte-p size i) (integerp count) (<= count 0)) (unsigned-byte-p size (ash i count))))
Theorem:
(defthm ash-goes-to-0 (implies (and (unsigned-byte-p size i) (integerp count) (<= count 0) (<= size (- count))) (equal (ash i count) 0)))