102 lines
3.3 KiB
Ruby
102 lines
3.3 KiB
Ruby
module Arm
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class CompareInstruction < Register::Instruction
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include Constants
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include Attributed
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def initialize(left , right , attributes)
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super(nil)
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@attributes = attributes
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@left = left
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@right = right.is_a?(Fixnum) ? IntegerConstant.new(right) : right
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@attributes[:condition_code] = :al if @attributes[:condition_code] == nil
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@operand = 0
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@attributes[:update_status] = 1
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@rn = left
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@rd = :r0
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end
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def assemble(io)
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# don't overwrite instance variables, to make assembly repeatable
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rn , operand , immediate= @rn , @operand , 1
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arg = @right
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if arg.is_a?(Parfait::Object)
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# do pc relative addressing with the difference to the instuction
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# 8 is for the funny pipeline adjustment (ie oc pointing to fetch and not execute)
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arg = arg.position - self.position - 8
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rn = :pc
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end
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operand = Register::RegisterValue.new( arg , :Integer) if( arg.is_a? Symbol )
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case operand
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when Numeric
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operand = handle_numeric(arg)
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when Symbol , ::Register::RegisterValue
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immediate = 0
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when Arm::Shift
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handle_shift
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else
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raise "invalid operand argument #{arg.inspect} , #{inspect}"
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end
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val = (operand.is_a?(Symbol) or operand.is_a?(::Register::RegisterValue)) ? reg_code(operand) : operand
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val = 0 if val == nil
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val = shift(val , 0)
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raise inspect unless reg_code(@rd)
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val |= shift(reg_code(@rd) , 12)
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val |= shift(reg_code(rn) , 12 + 4)
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val |= shift(@attributes[:update_status], 12 + 4 + 4)#20
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val |= shift(op_bit_code , 12 + 4 + 4 + 1)
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val |= shift(immediate , 12 + 4 + 4 + 1 + 4)
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val |= instruction_code
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val |= condition_code
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io.write_uint32 val
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end
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def handle_numeric(arg)
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if (arg.fits_u8?) # no shifting needed
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return arg
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elsif (op_with_rot = calculate_u8_with_rr(arg))
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#operand = op_with_rot
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raise "hmm"
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else
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raise "cannot fit numeric literal argument in operand #{arg.inspect}"
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end
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end
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def instuction_class
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0b00 # OPC_DATA_PROCESSING
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end
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# Arms special shift abilities are not modelled in the register level
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# So they would have to be used inoptimisations, that are not implemented
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# in short unused code
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def handle_shift
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# rm_ref = arg.argument
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# immediate = 0
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# shift_op = {'lsl' => 0b000, 'lsr' => 0b010, 'asr' => 0b100,
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# 'ror' => 0b110, 'rrx' => 0b110}[arg.type]
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# if (arg.type == 'ror' and arg.value.nil?)
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# # ror #0 == rrx
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# raise "cannot rotate by zero #{arg} #{inspect}"
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# end
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#
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# arg1 = arg.value
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# if (arg1.is_a?(Register::IntegerConstant))
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# if (arg1.value >= 32)
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# raise "cannot shift by more than 31 #{arg1} #{inspect}"
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# end
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# shift_imm = arg1.value
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# elsif (arg1.is_a?(Arm::Register))
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# shift_op val |= 0x1;
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# shift_imm = arg1.number << 1
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# elsif (arg.type == 'rrx')
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# shift_imm = 0
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# end
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# operand = rm_ref | (shift_op << 4) | (shift_imm << 4 +3)
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raise "No implemented"
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end
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def to_s
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"#{opcode} #{@left} , #{@right} #{super}"
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end
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end
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end
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