84 lines
3.3 KiB
Ruby
84 lines
3.3 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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reg = reg.to_reg() if reg.is_a?( RegisterSlot )
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raise "not reg value or slot #{reg}" unless reg.is_a?(RegisterValue)
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to_mem("#{reg.class_name} -> #{register.class_name}[#{index}]" , reg)
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end
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# for chaining the array operator is defined here too.
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# It basically reduces the slot to a register and applies the [] on that reg.
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# thus returning a new RegisterSlot.
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# Example: message[:caller][:next_message]
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# message[:caller] returns a RegisterSlot, which would be self for this example
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# to evaluate self[:next_message] we reduce self to a register with to_reg
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def []( index )
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reg = to_reg()
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reg[index]
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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 register 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()
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source = "reduce #{@register.symbol}[#{@index}]"
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slot_to_reg = Risc.slot_to_reg(source , register, index)
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if compiler
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compiler.add_code(slot_to_reg)
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slot_to_reg.register.set_compiler(compiler)
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end
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slot_to_reg.register
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end
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# just pass the call through. That is we create the register (call to_reg)
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# and call reduce_int on the result
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# Just so the dsl code can be a bit shorter / less cluttered
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def reduce_int(bool)
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to_reg.reduce_int(bool)
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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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raise "Index must be register #{index}" unless(index.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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