109 lines
3.0 KiB
Ruby
109 lines
3.0 KiB
Ruby
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# $Id: lv.rb 14 2008-03-02 05:42:30Z warchild $
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#
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# Copyright (c) 2008, Jon Hart
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# All rights reserved.
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#
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# Redistribution and use in source and binary forms, with or without
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# modification, are permitted provided that the following conditions are met:
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# * Redistributions of source code must retain the above copyright
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# notice, this list of conditions and the following disclaimer.
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# * Redistributions in binary form must reproduce the above copyright
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# notice, this list of conditions and the following disclaimer in the
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# documentation and/or other materials provided with the distribution.
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# * Neither the name of the <organization> nor the
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# names of its contributors may be used to endorse or promote products
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# derived from this software without specific prior written permission.
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#
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# THIS SOFTWARE IS PROVIDED BY Jon Hart ``AS IS'' AND ANY
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# EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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# DISCLAIMED. IN NO EVENT SHALL Jon Hart BE LIABLE FOR ANY
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# DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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# (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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# ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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#
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module Racket
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module Misc
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# Simple class to represent data structures that
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# consist of an arbitrary number of length value pairs.
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class LV
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# An array containing the values parsed from this LV
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attr_accessor :values
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# The lengths of the values parsed from this LV
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attr_accessor :lengths
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# everything else
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attr_accessor :rest
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# Create a new LV object whose L sizes are specified in +args+
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def initialize(*args)
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@sizes = args
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@values = []
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@lengths = []
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end
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def decode(data)
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n = 0
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values = []
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lengths = []
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@sizes.each do |s|
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# XXX: raise an error here if there is not enough data to
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# unpack this next LV
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lengths[n] = data.unpack("#{punpack_string(s)}")[0]
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data = data.slice(s, data.length)
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values[n] = data.unpack("a#{lengths[n]}")[0]
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data = data.slice(lengths[n], data.length)
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n += 1
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end
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# data now contains "rest"
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[lengths, values, data]
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end
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def decode!(data)
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@lengths, @values, @rest = self.decode(data)
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end
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def encode
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n = 0
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s = ""
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@lengths.each do |l|
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s << [l].pack("#{punpack_string(@sizes[n])}")
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s << [@values[n]].pack("a#{l}")
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n += 1
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end
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s
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end
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def to_s
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encode
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end
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def to_str
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encode
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end
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private
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def punpack_string(size)
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s = ""
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case size
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when 1
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s << "C"
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when 2
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s << "n"
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when 4
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s << "N"
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else
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raise ArgumentError, "Size #{s} not supported"
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end
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s
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end
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end
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end
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end
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# vim: set ts=2 et sw=2:
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