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; EXLD (execloader) Library
; Note: The license below is based on the template at:
; http://opensource.org/licenses/BSD-3-Clause
; Copyright (C) 2015, Regents of the University of Texas
; All rights reserved.
; Redistribution and use in source and binary forms, with or without
; modification, are permitted provided that the following conditions are
; met:
; o Redistributions of source code must retain the above copyright
; notice, this list of conditions and the following disclaimer.
; o Redistributions in binary form must reproduce the above copyright
; notice, this list of conditions and the following disclaimer in the
; documentation and/or other materials provided with the distribution.
; o Neither the name of the copyright holders nor the names of its
; contributors may be used to endorse or promote products derived
; from this software without specific prior written permission.
; THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
; "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
; LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
; A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
; HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
; SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
; LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
; DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
; THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
; (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
; OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
; Original Author(s):
; Shilpi Goel <shigoel@cs.utexas.edu>
; Warren A. Hunt, Jr. <hunt@cs.utexas.edu>
; [Shilpi Goel] This book is a generalized version of older books
; present in projects/x86isa/tools/execution/exec-loaders.
;; ----------------------------------------------------------------------
(in-package "EXLD")
(include-book "std/lists/take" :dir :system)
(include-book "std/lists/nthcdr" :dir :system)
(include-book "kestrel/fty/byte-list" :dir :system)
(include-book "centaur/bitops/merge" :dir :system)
(local (xdoc::set-default-parents execloader))
;; ----------------------------------------------------------------------
(define bytes->charlist ((bytes byte-listp))
:short "Convert a list of bytes to a list of characters."
:returns (lst character-listp :hyp (byte-listp bytes))
(if (endp bytes)
nil
(cons (code-char (car bytes))
(bytes->charlist (cdr bytes)))))
(define charlist->bytes ((charlist character-listp))
:short "Convert a list of characters to a list of bytes."
:returns (bl byte-listp :hyp :guard)
:prepwork ((local (in-theory (e/d (acl2::bytep) ()))))
(if (endp charlist)
nil
(cons (char-code (car charlist))
(charlist->bytes (cdr charlist))))
///
(defret same-length-of-byte-and-character-lists
(implies (character-listp charlist)
(equal (len bl) (len charlist)))))
(define string->bytes ((str stringp))
:short "Convert a string to a list of bytes."
:returns (bl byte-listp :hyp :guard
:hints (("Goal"
:in-theory (e/d () (str::coerce-to-list-removal)))))
(charlist->bytes (coerce str 'LIST)))
(define bytes->string ((bytes byte-listp))
:short "Convert a list of bytes to a string."
:returns (str stringp :hyp :guard)
(coerce (bytes->charlist bytes) 'STRING))
(define take-till-zero ((bytes byte-listp))
:short "Return all initial elements of @('bytes') until a @('0')
element is encountered or the end of @('bytes') is reached,
whichever happens first."
:returns (bs byte-listp :hyp :guard)
(if (endp bytes)
nil
(if (equal (car bytes) 0)
nil
(cons (car bytes) (take-till-zero (cdr bytes))))))
;; ----------------------------------------------------------------------
(define merge-bytes ((bytes byte-listp))
:short "Concatenates @('bytes') (least-significant byte appears
first) to form a single natural number"
:returns (merged natp :rule-classes :type-prescription)
(bitops::merge-unsigneds 8 (acl2::reverse bytes))
///
(local (in-theory (e/d () (unsigned-byte-p))))
(defret width-of-<fn>
(implies (and (<= (* 8 (len bytes)) m) (natp m))
(unsigned-byte-p m merged))))
(define split-bytes ((n natp)
(bytes byte-listp))
:short "Split @('bytes') into two lists, where first part has @('n') elements"
:returns (mv (one byte-listp :hyp (byte-listp bytes))
(two byte-listp :hyp (byte-listp bytes)))
(b* ((rest (nthcdr n bytes))
((unless (<= n (len bytes)))
(prog2$
(raise "Not enough bytes to split into two by ~x0! (len bytes): ~x1" n (len bytes))
(mv (make-list n :initial-element 0) rest)))
(first (take n bytes)))
(mv first rest))
///
(defret len-of-mv-nth-0-<fn>
(equal (len one) (nfix n)))
(defret len-of-mv-nth-1-<fn>
(equal (len two) (nfix (- (len bytes) (nfix n))))))
(define merge-first-split-bytes ((n natp)
(bytes byte-listp))
:short "Merge first @('n') bytes (least-significant byte first) from
@('bytes'); return remaining bytes"
:returns (mv (merged-num natp :rule-classes :type-prescription)
(rest byte-listp :hyp (byte-listp bytes)))
(b* (((mv first rest) (split-bytes n bytes)))
(mv (merge-bytes first) rest))
///
(local (in-theory (e/d () (unsigned-byte-p))))
(defret width-of-mv-nth-0-<fn>
(implies (and (equal m (* 8 n)) (natp n))
(unsigned-byte-p m merged-num))
:hints (("Goal" :do-not-induct t
:use ((:instance len-of-mv-nth-0-split-bytes (n n) (bytes bytes))
(:instance width-of-merge-bytes
(m (* 8 n))
(bytes (mv-nth 0 (split-bytes n bytes)))))
:in-theory (e/d ()
(len-of-mv-nth-0-split-bytes
width-of-merge-bytes)))))
(defret len-of-mv-nth-1-<fn>
(equal (len rest) (nfix (- (len bytes) (nfix n))))))
;; ----------------------------------------------------------------------
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