		Search-engine friendly clone of the ACL2 documentation.

State-stobj

Read1-memory-unsigned16

Refine read-memory-unsigned16 to use the stobj states.

Definitions and Theorems

Function: read1-memory-unsigned16

(defun read1-memory-unsigned16 (addr stat feat)
 (declare (xargs :non-executable t))
 (declare
    (xargs :guard (non-exec (and (stat1p stat)
                                 (integerp addr)
                                 (statp (stat-from-stat1 stat))
                                 (featp feat)
                                 (stat-validp (stat-from-stat1 stat)
                                              feat)))))
 (prog2$
  (acl2::throw-nonexec-error 'read1-memory-unsigned16
                             (list addr stat feat))
  (let ((feat1 (stat1p stat)))
   (cond
       ((acl2::mbt$ feat1)
        (let ((b0 (read-memory-unsigned8 addr (stat-from-stat1 stat)
                                         feat))
              (stat (stat-from-stat1 stat)))
          (let ((b1 (read-memory-unsigned8 (+ (lifix addr) 1)
                                           stat feat)))
            (cond ((feat-little-endianp feat)
                   (logapp 8 b0 (logapp 8 b1 0)))
                  ((feat-big-endianp feat)
                   (logapp 8 b1 (logapp 8 b0 0)))
                  (t (acl2::impossible-fn))))))
       (t 0)))))

Theorem: read1-memory-unsigned16-to-read-memory-unsigned16

(defthm read1-memory-unsigned16-to-read-memory-unsigned16
 (implies (stat1p stat)
          (equal (read1-memory-unsigned16 addr stat feat)
                 (read-memory-unsigned16 addr (stat-from-stat1 stat)
                                         feat)))
 :rule-classes :rewrite)

Theorem: read-memory-unsigned16-to-read1-memory-unsigned16

(defthm read-memory-unsigned16-to-read1-memory-unsigned16
  (implies
       (statp stat)
       (equal (read-memory-unsigned16 addr stat feat)
              (read1-memory-unsigned16 addr (stat1-from-stat stat)
                                       feat)))
  :rule-classes :rewrite)