67 lines
1.3 KiB
Ruby
67 lines
1.3 KiB
Ruby
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module Intel
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##
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# Label is a known point in the byte stream that we can jmp/loop back to.
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class Label < Operand
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attr_accessor :position
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def initialize machine , position = nil
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super( machine)
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@position = position
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end
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def bits
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distance = machine.stream.size - position
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if distance < 256 then
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8
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elsif distance < 65536 then
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16
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else
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32
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end
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end
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end
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##
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# FutureLabel is a label in memory that hasn't been defined yet and
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# will go back and fill in the appropriate memory bytes later
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class FutureLabel < Label
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attr_accessor :positions
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def initialize(machine)
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super( machine )
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self.positions = []
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end
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def plant
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self.position = machine.stream.size
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positions.each do |each|
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size = machine.stream[each + 1]
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address = []
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case size
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when 2 then
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address.push_B(position - each - 2)
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when 3 then
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address.push_W(position - each - 3)
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when 5 then
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address.push_D(position - each - 5)
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else
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raise "unhandled size #{size}"
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end
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address.each_with_index do |byte, index|
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idx = each + index + 1
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machine.stream[idx] = byte
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end
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end
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end
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def add aPosition
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positions << aPosition
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end
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end
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end
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