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Read-bytes$

Read-16ube

(read-16ube channel state) reads a 16-bit, unsigned, big-endian value from the input channel.

Definitions and Theorems

Function: read-16ube

(defun read-16ube (channel state)
  (declare (xargs :guard (and (state-p state)
                              (symbolp channel)
                              (open-input-channel-p channel
                                                    :byte state))))
  (b* (((mv x1 state)
        (read-byte$ channel state))
       ((mv x2 state)
        (read-byte$ channel state))
       ((unless x1) (mv nil state))
       ((unless x2) (mv 'fail state)))
    (mv (combine16u x1 x2) state)))

Theorem: read-16ube-unsigned-byte

(defthm read-16ube-unsigned-byte
  (implies (and (force (state-p1 state))
                (force (open-input-channel-p1 channel
                                              :byte state))
                (force (symbolp channel))
                (mv-nth 0 (read-16ube channel state))
                (not (equal (mv-nth 0 (read-16ube channel state))
                            'fail)))
           (unsigned-byte-p 16
                            (mv-nth 0 (read-16ube channel state)))))

Theorem: read-16ube-integer

(defthm read-16ube-integer
  (implies (and (mv-nth 0 (read-16ube channel state))
                (not (equal (mv-nth 0 (read-16ube channel state))
                            'fail)))
           (integerp (mv-nth 0 (read-16ube channel state)))))

Theorem: read-16ube-range

(defthm read-16ube-range
  (implies (and (force (state-p1 state))
                (force (open-input-channel-p1 channel
                                              :byte state))
                (force (symbolp channel))
                (mv-nth 0 (read-16ube channel state))
                (not (equal (mv-nth 0 (read-16ube channel state))
                            'fail)))
           (and (<= 0 (mv-nth 0 (read-16ube channel state)))
                (< (mv-nth 0 (read-16ube channel state))
                   65536)
                (< (mv-nth 0 (read-16ube channel state))
                   (expt 2 16))))
  :rule-classes :linear)

Theorem: read-16ube-state

(defthm read-16ube-state
  (implies (and (force (state-p1 state))
                (force (open-input-channel-p1 channel
                                              :byte state))
                (force (symbolp channel)))
           (state-p1 (mv-nth 1 (read-16ube channel state)))))

Theorem: read-16ube-open-input-channel-p1

(defthm read-16ube-open-input-channel-p1
  (implies (and (force (state-p1 state))
                (force (open-input-channel-p1 channel
                                              :byte state))
                (force (symbolp channel)))
           (open-input-channel-p1
                channel
                :byte (mv-nth 1 (read-16ube channel state)))))