69 lines
2.6 KiB
Ruby
69 lines
2.6 KiB
Ruby
module Risc
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# A RegisterSlot is a description of a slot into an object in a register.
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#
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# In many ways, it is like a variable in programming it can be a value, or it
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# can be assigned a value. An l-value or r-value, and since we don't know at
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# the time they are created (because of the dsl nature) we delay.
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#
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# RegisterSlots are created trough the array operator on a register.
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# ie message[:caller], and this can either be further indexed, assigned
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# something or assigned to something. So we overload those operators here.
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#
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# Ultimately SlotToReg or RegToSlot instructions are created for the l-value
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# or r-vlalue respectively.
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class RegisterSlot
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attr_reader :register , :index , :compiler
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def initialize(register, index , compiler)
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@register , @index , @compiler = register , index , compiler
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end
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# fullfil the objects purpose by creating a RegToSlot instruction from
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# itself (the slot) and the register given
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def <<( reg )
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case reg
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when RegisterValue
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puts reg.symbol
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to_mem("#{reg.class_name} -> #{register.class_name}[#{index}]" , reg)
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when RegisterSlot
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puts reg.register.symbol
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reg = to_reg("reduce #{@register.symbol}[@index]")
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to_mem("#{reg.class_name} -> #{register.class_name}[#{index}]" , reg)
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else
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raise "not reg value or slot #{reg}"
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end
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end
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# push the given register into the slot that self represents
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# ie create a slot_to_reg instruction and add to the compiler
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# the register represents and "array", and the content of the
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# given register from, is pushed to the memory at register[index]
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def to_mem(source , from )
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reg_to_slot = Risc.reg_to_slot(source , from , register, index)
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compiler.add_code(reg_to_slot) if compiler
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reg_to_slot.register
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end
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# load the conntent of the slot that self descibes into a a new register.
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# the regsiter is created, and the slot_to_reg instruction added to the
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# compiler. the return is a bit like @register[@index]
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def to_reg(source )
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slot_to_reg = Risc.slot_to_reg(source , register, index)
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compiler.add_code(slot_to_reg) if compiler
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slot_to_reg.register
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end
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# similar to above (<< which produces reg_to_slot), this produces reg_to_byte
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# from itself (the slot) and the register given
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def <=( reg )
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raise "not reg #{reg}" unless reg.is_a?(RegisterValue)
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reg_to_byte = Risc.reg_to_byte("#{reg.class_name} -> #{register.class_name}[#{index}]" , reg , register, index)
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compiler.add_code(reg_to_byte) if compiler
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reg_to_byte
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end
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end
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end
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