Method: MicroCisc::Compile::Instruction#encoded

Defined in:

lib/micro_cisc/compile/instruction.rb

#encoded(label_dictionary = nil, current_address = nil) ⇒ Object

# File 'lib/micro_cisc/compile/instruction.rb', line 253

def encoded(label_dictionary = nil, current_address = nil)
  imms = @immediates.map do |imm|
    if imm.is_a?(Numeric)
      imm
    elsif label_dictionary.nil?
      0
    elsif imm.is_a?(Array)
      raise ArgumentError, 'Current address is missing' if current_address.nil?
      label_address = label_dictionary[imm.first]
      raise ArgumentError, "Missing label '#{imm.first}'" if label_address.nil?
      label_address = label_address & 0xFFFF
      if imm.last == 'disp'
        label_address - current_address
      elsif imm.last == 'imm'
        label_address & 0xFFFF
      else
        raise ArgumentError, "Invalid immediate spec: #{imm.first}.#{imm.last}"
      end
    else
      raise ArgumentError, "Invalid immediate spec: #{imm.first}.#{imm.last}"
    end
  end

  op_code = @operation == 'alu' ? 1 : 0
  msb = (op_code << 7) | (@eff << 5) | (@dest << 2) | (@src >> 1)
  lsb = ((@src & 0x01) << 7)

  if @uses_mem_arg
    lsb = lsb | (@inc << 6)
  end

  imm_mask = ~(-1 << @bit_width)
  if @operation == 'alu'
    lsb = lsb | ((imms.first & imm_mask) << 4) | (@alu_code & 0xF)
  else
    imm =
      if @source_is_mem && @dest_is_mem
        ((imms.first & 0x7) << 3) | (imms.last & 0x7)
      else
        imms.first
      end
    lsb = lsb | (imm & imm_mask)
  end

  ((msb & 0xFF) << 8) | (lsb & 0xFF)
end