jalr tests

cpu_test.rb

  def test_jalr
    cpu = Cpu.new

    # XXX: 行き当たりばったりに書いたのでゴチャゴチャしてる...
    rom = [
      _addi(2, 0, 40),  # x2 = foo
      _jalr(1, 2, 0),   # call foo （ t=pc+4; pc=(x2+0) & ~1; x1=t ）
      _add(31, 29, 30), # x31 = x29 + x30
      _nop,
      _jalr(1, 31, -5), # call bar （ t=pc+4; pc=(x31-5)&~1）; x1=t ）
      _addi(28, 0, 49), # x28 = 49
      # bar:
      _addi(27, 0, 46), # x27 = 46
      _jalr(0, 1, 0),   # ret
      _nop,
      _nop,
      # foo:
      _addi(29, 0, 10), # x29 = 10
      _addi(30, 0, 20), # x30 = 20
      _jalr(0, 1, 0)    # ret
    ].pack("l*")
    cpu.init_memory(rom)

    cpu.run # x2 = 40
    cpu.run # jalr x1, x2, 0

    assert_equal 40, cpu.pc
    assert_equal 8, cpu.x_registers[1]

    cpu.run # x29 = 10
    cpu.run # x30 = 20
    cpu.run # ret

    assert_equal 8, cpu.pc

    cpu.run # x31 = x29 + x30

    assert_equal 30, cpu.x_registers[31]

    cpu.run # nop
    cpu.run # jalr x1, x31, -5

    assert_equal 24, cpu.pc
    assert_equal 20, cpu.x_registers[1]

    cpu.run # x27 = 46
    cpu.run # ret
    cpu.run # x28 = 49

    assert_equal 24, cpu.pc
    assert_equal 46, cpu.x_registers[27]
    assert_equal 49, cpu.x_registers[28]
  end