def test_fx55_writes_registers_to_ram(self, max_register):
"""Fx55 writes register contents to RAM correctly"""
vm = Chip8VirtualMachine()
self._write_values_to_memory(
vm, max_register, 0xA00, 128
)
for index in range(0, max_register+1):
assert vm.memory[0xA00 + index] == 128 + index
def test_fx65_loads_ram_to_registers(self, max_register):
"""Fx65 reads ram contents to registers correctly"""
vm = Chip8VirtualMachine()
self._load_from_memory(
vm, max_register, 0xA00, 128
)
for register_index in range(0, max_register+1):
assert vm.v_registers[register_index] == 128 + register_index
def test_fx07_set_vx_to_delay_timer_value(
v_register_index,
v_initial_value,
delay_timer_value
):
vm = Chip8VirtualMachine()
vm.delay_timer = delay_timer_value
load_and_execute_instruction(vm, 0xF007, x=v_register_index)
assert vm.v_registers[v_register_index] == delay_timer_value
def test_fx65_does_not_touch_other_registers(self, max_register):
"""Fx65 doesn't touch registers past x"""
vm = Chip8VirtualMachine()
self._load_from_memory(
vm, max_register, 0xA00, 128
)
# memory outside of the write area isn't touched, excludes
# the load point of the fx55 instruction
for register_index in range(max_register + 1, 16):
assert vm.v_registers[register_index] == 0
def test_fx55_does_not_touch_other_memory(self, write_location):
"""Fx55 doesn't touch RAM outside the range it's supposed to"""
vm = Chip8VirtualMachine()
self._write_values_to_memory(
vm, 0xF, write_location, 128
)
# memory outside of the write area isn't touched, excludes
# the load point of the fx55 instruction
for memory_index in chain(
range(0x202, write_location),
range(write_location + 18, len(vm.memory))
):
assert vm.memory[memory_index] == 0
def test_fx1e_adds_vx_to_i_register(
source_register: int,
initial_i: int,
value_to_add: int):
"""
FX1E Adds VX and I, storing the result in I
:param source_register: which register will be pulled from
:param initial_i: initial value for i to hold
:param value_to_add: value that will be added to the I register
"""
vm = Chip8VirtualMachine()
vm.i_register = initial_i
vm.v_registers[source_register] = value_to_add
load_and_execute_instruction(vm, 0xF01E, x=source_register)
assert vm.i_register == initial_i + value_to_add
def test_fx15_sets_delay_timer_from_vx(
self,
source_register,
initial_delay_value,
set_value
):
"""
FX15 sets delay timer to value in VX
:param source_register: which VX register to set DT from
:param initial_delay_value: the value DT will initially hold
:param set_value: the value DT will have after setting
:return:
"""
vm = Chip8VirtualMachine()
vm.delay_timer = initial_delay_value
vm.v_registers[source_register] = set_value
load_and_execute_instruction(vm, 0xF015, x=source_register)
assert vm.delay_timer == set_value
def test_fx29_load_address_for_digit_sprite_to_i(
digit_to_sprite,
digit_storage_start
):
"""
FX29 Loads address for the sprite of the digit in VX to I register
:param digit_to_sprite: digit to load sprite for, 0-16
:param digit_storage_start: where digits will be stored in RAM
:return:
"""
vm = Chip8VirtualMachine(digit_start=digit_storage_start)
for source_register in range(0, 16):
vm.program_counter = EXECUTION_START
vm.v_registers[source_register] = digit_to_sprite
load_and_execute_instruction(vm, 0xF029, x=source_register)
i = vm.i_register
assert vm.memory[i:i+vm.digit_length] ==\
DEFAULT_DIGITS[digit_to_sprite]
def test_fx33_store_bcd_of_vx_starting_at_i(
v_register_index,
i_reg_value,
value_to_bcd,
expected_result_digits
):
"""
FX33 Stores BCD of the value in VX starting at location in I register
:param v_register_index: which x register to use
:param i_reg_value: where in memory to store the bcd
:param value_to_bcd: what will be converted
:param expected_result_digits: the expected digit output
:return:
"""
vm = Chip8VirtualMachine()
vm.i_register = i_reg_value
vm.v_registers[v_register_index] = value_to_bcd
load_and_execute_instruction(vm, 0xF033, x=v_register_index)
for index, digit in enumerate(expected_result_digits):
assert vm.memory[i_reg_value + index] == digit
def test_valuerror_on_unhandled_instruction(
patterned_unrecognizeable_instruction):
"""Unhandled instructions raise ValueError"""
vm = Chip8VirtualMachine()
with pytest.raises(ValueError):
load_and_execute_instruction(vm, patterned_unrecognizeable_instruction)
def test_ram_size(ram_size):
vm = Chip8VirtualMachine(memory_size=ram_size)
print(vm.memory)
assert len(vm.memory) == ram_size
def test_typeerror_on_not_a_type(self):
"""Non-type passed in video_ram_type"""
with pytest.raises(TypeError):
vm = Chip8VirtualMachine(video_ram_type="not a type")
def test_typeerror_on_bad_vram_type(self):
"""Non-VideoRam class passed in video_ram_type"""
with pytest.raises(TypeError):
vm = Chip8VirtualMachine(video_ram_type=BadClass)
def test_vm_raises_no_error_on_good_types(self, vram_type):
vm = Chip8VirtualMachine(video_ram_type=vram_type)