46 lines
1.6 KiB
Ruby
46 lines
1.6 KiB
Ruby
module Register
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# SetSlot moves data into memory from a register.
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# GetSlot moves data into a register from memory.
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# Both use a base memory (a register)
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# While the virtual machine has only one instruction (Set) to move data between slots,
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# the register has two, namely GetSlot and SetSlot
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#
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# This is because that is what cpu's can do. In programming terms this would be accessing
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# an element in an array, in the case of SetSlot setting the register in the array.
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# btw: to move data between registers, use RegisterTransfer
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class SetSlot < Instruction
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# If you had a c array and index offset
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# the instruction would do array[index] = register
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# So SetSlot means the register (first argument) moves to the slot (array and index)
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def initialize register , array , index
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@register = register
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@array = array
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@index = index
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raise "not integer #{index}" unless index.is_a? Numeric
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raise "Not register #{register}" unless Register::RegisterReference.look_like_reg(register)
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raise "Not register #{array}" unless Register::RegisterReference.look_like_reg(array)
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end
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attr_accessor :register , :array , :index
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def to_s
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"SetSlot(#{register}: #{array}[#{index}])"
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end
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end
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# Produce a SetSlot instruction.
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# From and to are registers or symbols that can be transformed to a register by resolve_to_register
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# index resolves with resolve_index.
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def self.set_slot from , to , index
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index = resolve_index( to , index)
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from = resolve_to_register from
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to = resolve_to_register to
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SetSlot.new( from , to , index)
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end
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end
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