53 lines
2.2 KiB
Ruby
53 lines
2.2 KiB
Ruby
module Risc
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module Position
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# Instructions are also a linked list, but their position is not really
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# the position of the object.
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# Rather it is the position of the assembled code in the binary.
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# (Luckily arm is sane, so this is realtively simple)
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#
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# Really we only need to calculate Positions at a jump, so between the
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# Jump and the label it jumps too. The other instructions are "just" fill.
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# But off course we need to propagate positions to get it right.
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#
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# Assembled instructions are kept in BinaryCode objects.
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# When propagating positions we have to see that the next position assembles into
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# the same BinaryCode, or else move it and the code along
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#
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class InstructionPosition < ObjectPosition
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attr_reader :instruction , :binary
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def initialize(instruction, pos , binary)
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raise "not set #{binary}" if pos != 0 and !binary.is_a?(Parfait::BinaryCode)
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super(instruction,pos)
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@instruction = instruction
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@binary = binary
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end
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def init(at, binary)
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@binary = binary
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instruction.address.set_value(at) if instruction.is_a?(Label)
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return if at == 0 and binary.nil?
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raise "faux pas" if at < Position.get(binary).at
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return unless @instruction.next
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nekst = at + @instruction.byte_length
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diff = nekst - Position.get(@binary).at
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Position.log.debug "Diff: #{diff.to_s(16)} , next #{nekst.to_s(16)} , binary #{Position.get(@binary)}"
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raise "Invalid position #{diff.to_s(16)} , next #{nekst.to_s(16)} #{self}" if diff < 8
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if( (diff % (binary.padded_length - @instruction.byte_length)) == 0 )
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binary.extend_one unless binary.next
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binary = binary.next
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raise "end of line " unless binary
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nekst = Position.get(binary).at + Parfait::BinaryCode.byte_offset
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Position.log.debug "Jump to: #{nekst.to_s(16)}"
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end
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Position.set(@instruction.next, nekst , binary)
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end
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def reset_to(pos , binary)
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super(pos , binary)
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init(pos , binary)
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Position.log.debug "ResetInstruction (#{pos.to_s(16)}) #{instruction}"
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end
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end
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end
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end
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