66 lines
2.0 KiB
Ruby
66 lines
2.0 KiB
Ruby
module Risc
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# Positions are very different during compilation and run-time.
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# At run-time they are inherrent to the object, and fixed.
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# While during compilation we can move things about, and do not use the
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# objects memory position at all.
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#
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# Furthermore, there are differnet kind of positions during compilation.
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# Off course the object position as hinted above, but also instruction
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# positions, that do not reflect the position of the object, but of the
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# assembled instruction in the binary.
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#
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# The Position class keeps a hash of all compile time positions.
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#
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# While the Position objects transmit the change that (re) positioning
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# entails to affected objects.
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class Position
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@positions = {}
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attr_reader :at
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def initialize( at )
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@at = at
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raise "not int #{self}-#{at}" unless @at.is_a?(Integer)
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end
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def +(offset)
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offset = offset.at if offset.is_a?(Position)
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@at + offset
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end
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def -(offset)
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offset = offset.at if offset.is_a?(Position)
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@at - offset
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end
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def to_s
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"0x#{@at.to_s(16)}"
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end
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def self.positions
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@positions
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end
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def self.position(object)
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pos = self.positions[object]
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if pos == nil
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str = "position accessed but not set, "
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str += "0x#{object.object_id.to_s(16)}\n"
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str += "for #{object.class} byte_length #{object.byte_length if object.respond_to?(:byte_length)} for #{object.inspect[0...130]}"
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raise str
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end
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pos
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end
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def self.set_position( object , pos )
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# resetting of position used to be error, but since relink and dynamic instruction size it is ok.
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# in measures (of 32)
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#puts "Setting #{pos} for #{self.class}"
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old = Position.positions[object]
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if old != nil and ((old - pos).abs > 1000)
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raise "position set too far off #{pos}!=#{old} for #{object}:#{object.class}"
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end
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self.positions[object] = Position.new( pos )
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end
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end
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end
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