def __init__(self):
self.registers = bytearray(self.REG_COUNT)
self.index_register = 0
self.program_counter = self.ENTRY_POINT
self.memory = Memory()
self.screen = Screen()
self.keyboard = bytearray(self.KEY_COUNT)
self.stack = []
self.delay_timer = 0
self.sound_timer = 0
self.INSTRUCTION_SET = {
0x00E0: self.op_00E0,
0x00EE: self.op_00EE,
0x1: self.op_1NNN,
0x2: self.op_2NNN,
0x3: self.op_3XNN,
0x4: self.op_4XNN,
0x5: self.op_5XY0,
0x6: self.op_6XNN,
0x7: self.op_7XNN,
0x8000: self.op_8XY0,
0x8001: self.op_8XY1,
0x8002: self.op_8XY2,
0x8003: self.op_8XY3,
0x8004: self.op_8XY4,
0x8005: self.op_8XY5,
0x8006: self.op_8XY6,
0x8007: self.op_8XY7,
0x800E: self.op_8XYE,
0x9000: self.op_9XY0,
0xA: self.op_ANNN,
0xB: self.op_BNNN,
0xC: self.op_CXNN,
0xD: self.op_DXYN,
0xE09E: self.op_EX9E,
0xE0A1: self.op_EXA1,
0xF007: self.op_FX07,
0xF00A: self.op_FX0A,
0xF015: self.op_FX15,
0xF018: self.op_FX18,
0xF01E: self.op_FX1E,
0xF029: self.op_FX29,
0xF033: self.op_FX33,
0xF055: self.op_F055,
0xF065: self.op_FX65,
}
def __init__(self):
self.registers = bytearray(self.REG_COUNT)
self.index_register = 0
self.program_counter = self.ENTRY_POINT
self.memory = Memory()
self.screen = Screen()
self.keyboard = bytearray(self.KEY_COUNT)
self.stack = []
self.delay_timer = 0
self.sound_timer = 0
self.INSTRUCTION_SET = {
0x00E0: self.op_00E0,
0x00EE: self.op_00EE,
0x1 : self.op_1NNN,
0x2 : self.op_2NNN,
0x3 : self.op_3XNN,
0x4 : self.op_4XNN,
0x5 : self.op_5XY0,
0x6 : self.op_6XNN,
0x7 : self.op_7XNN,
0x8000: self.op_8XY0,
0x8001: self.op_8XY1,
0x8002: self.op_8XY2,
0x8003: self.op_8XY3,
0x8004: self.op_8XY4,
0x8005: self.op_8XY5,
0x8006: self.op_8XY6,
0x8007: self.op_8XY7,
0x800E: self.op_8XYE,
0x9000: self.op_9XY0,
0xA : self.op_ANNN,
0xB : self.op_BNNN,
0xC : self.op_CXNN,
0xD : self.op_DXYN,
0xE09E: self.op_EX9E,
0xE0A1: self.op_EXA1,
0xF007: self.op_FX07,
0xF00A: self.op_FX0A,
0xF015: self.op_FX15,
0xF018: self.op_FX18,
0xF01E: self.op_FX1E,
0xF029: self.op_FX29,
0xF033: self.op_FX33,
0xF055: self.op_F055,
0xF065: self.op_FX65,
}
class Chip8(object):
ENTRY_POINT = 0x200
REG_COUNT = 16
KEY_COUNT = 16
def __init__(self):
self.registers = bytearray(self.REG_COUNT)
self.index_register = 0
self.program_counter = self.ENTRY_POINT
self.memory = Memory()
self.screen = Screen()
self.keyboard = bytearray(self.KEY_COUNT)
self.stack = []
self.delay_timer = 0
self.sound_timer = 0
self.INSTRUCTION_SET = {
0x00E0: self.op_00E0,
0x00EE: self.op_00EE,
0x1 : self.op_1NNN,
0x2 : self.op_2NNN,
0x3 : self.op_3XNN,
0x4 : self.op_4XNN,
0x5 : self.op_5XY0,
0x6 : self.op_6XNN,
0x7 : self.op_7XNN,
0x8000: self.op_8XY0,
0x8001: self.op_8XY1,
0x8002: self.op_8XY2,
0x8003: self.op_8XY3,
0x8004: self.op_8XY4,
0x8005: self.op_8XY5,
0x8006: self.op_8XY6,
0x8007: self.op_8XY7,
0x800E: self.op_8XYE,
0x9000: self.op_9XY0,
0xA : self.op_ANNN,
0xB : self.op_BNNN,
0xC : self.op_CXNN,
0xD : self.op_DXYN,
0xE09E: self.op_EX9E,
0xE0A1: self.op_EXA1,
0xF007: self.op_FX07,
0xF00A: self.op_FX0A,
0xF015: self.op_FX15,
0xF018: self.op_FX18,
0xF01E: self.op_FX1E,
0xF029: self.op_FX29,
0xF033: self.op_FX33,
0xF055: self.op_F055,
0xF065: self.op_FX65,
}
def decode(self, op):
if op in [0x00E0, 0x00EE]: # special case
return (op, tuple())
instruction = I(op)
if instruction in [0x0, 0x1, 0x2, 0xA, 0xB]:
args = (NNN(op),)
elif instruction in [0x3, 0x4, 0x6, 0x7, 0xC]:
args = X(op), NN(op)
elif instruction == 0x5:
args = X(op), Y(op)
elif instruction == 0xD:
args = X(op), Y(op), N(op)
elif 0x8000 <= instruction <= 0x9000:
args = X(op), Y(op)
elif instruction >= 0xE:
args = (X(op),)
return instruction, args
def execute(self, instruction, args):
if instruction not in self.INSTRUCTION_SET:
raise NotImplementedError('{:04x} - {}'.format(instruction, args))
self.INSTRUCTION_SET.get(instruction)(*args)
def fetch(self):
return self.memory.read_word(self.program_counter)
def cycle(self):
word = self.fetch()
instruction, args = self.decode(word)
self.execute(instruction, args)
if self.delay_timer > 0:
self.delay_timer -= 1
if self.sound_timer > 0:
if self.sound_timer == 1:
self.beep()
self.sound_timer -= 1
def increment_program_counter(self):
self.program_counter += 0x2
def skip_next_instruction(self):
self.program_counter += 0x4
def wait_for_keypress(self):
raise NotImplementedError()
def beep(self):
print 'Beep!'
# INSTRUCTIONS
def op_00E0(self):
'Clear screen'
self.screen.clear()
self.increment_program_counter()
def op_00EE(self):
'Return from a subroutine.'
self.program_counter = self.stack.pop()
def op_1NNN(self, address):
'Jump to address NNN.'
self.program_counter = address
def op_2NNN(self, address):
'Execute subroutine starting at address NNN.'
self.increment_program_counter()
self.stack.append(self.program_counter)
self.program_counter = address
def op_3XNN(self, X, NN):
'Skip the following instruction if the value of VX == NN.'
if self.registers[X] == NN:
self.skip_next_instruction()
else:
self.increment_program_counter()
def op_4XNN(self, X, NN):
'Skip the following instruction if the value of VX != NN.'
if self.registers[X] != NN:
self.skip_next_instruction()
else:
self.increment_program_counter()
def op_5XY0(self, X, Y):
'Skip next instruction if the value of VX == the value of VY.'
if self.registers[X] == self.registers[Y]:
self.skip_next_instruction()
else:
self.increment_program_counter()
def op_6XNN(self, X, NN):
'Store number NN in register VX.'
self.registers[X] = NN
self.increment_program_counter()
def op_7XNN(self, X, NN):
'Add the value NN to register VX.'
self.registers[X] = byte(self.registers[X] + NN)
self.increment_program_counter()
def op_8XY0(self, X, Y):
'Store the value of register VY in register VX.'
self.registers[X] = self.registers[Y]
self.increment_program_counter()
def op_8XY1(self, X, Y):
'Set VX to VX OR VY'
self.registers[X] |= self.registers[Y]
self.increment_program_counter()
def op_8XY2(self, X, Y):
'Set VX to VX AND VY'
self.registers[X] &= self.registers[Y]
self.increment_program_counter()
def op_8XY3(self, X, Y):
'Set VX to VX XOR VY.'
self.registers[X] ^= self.registers[Y]
self.increment_program_counter()
def op_8XY4(self, X, Y):
'''Add the value of register VY to register VX
Set VF to 01 if a carry occurs
Set VF to 00 if a carry does not occur'''
value = self.registers[X] + self.registers[Y]
self.registers[X] = byte(value)
self.registers[0xF] = 1 if value > 0xFF else 0
self.increment_program_counter()
def op_8XY5(self, X, Y):
'''
Subtract the value of register VY from register VX
Set VF to 00 if a borrow occurs
Set VF to 01 if a borrow does not occur
'''
value = self.registers[X] - self.registers[Y]
self.registers[X] = byte(value)
self.registers[0xF] = 0 if value < 0 else 1
self.increment_program_counter()
def op_8XY6(self, X, Y):
'''
Store the value of register VY shifted right one bit in VX
Set VF to the least significant bit prior to the shift
'''
self.registers[X] = self.registers[Y] >> 1
self.registers[0xF] = self.registers[Y] & 1
self.increment_program_counter()
def op_8XY7(self, X, Y):
'''
Set register VX to the value of VY minus VX
Set VF to 00 if a borrow occurs
Set VF to 01 if a borrow does not occur
'''
value = self.registers[Y] - self.registers[X]
self.registers[X] = byte(value)
self.registers[0xF] = 0 if value < 0 else 1
self.increment_program_counter()
def op_8XYE(self, X, Y):
'''
Store the value of register VY shifted left one bit in VX
Set VF to the most significant bit prior to the shift
'''
self.registers[X] = byte(self.registers[Y] << 1)
self.registers[0xF] = self.registers[Y] >> 7
self.increment_program_counter()
def op_9XY0(self, X, Y):
'Skip the following instruction if the value VX != value VY.'
if self.registers[X] != self.registers[Y]:
self.skip_next_instruction()
else:
self.increment_program_counter()
def op_ANNN(self, address):
'Store memory address NNN in register I.'
self.index_register = address
self.increment_program_counter()
def op_BNNN(self, address):
'Jump to address NNN + V0.'
self.program_counter = address + self.registers[0]
def op_CXNN(self, X, NN):
'Set VX to a random number with a mask of NN.'
self.registers[X] = randint(0, 0xFF) & NN
self.increment_program_counter()
def op_DXYN(self, VX, VY, N):
x = self.registers[VX]
y = self.registers[VY]
sprite = self.memory.read(self.index_register, N)
collision = self.screen.draw(sprite, x, y)
self.registers[0xF] = bool(collision)
self.increment_program_counter()
def op_EX9E(self, X):
key = self.registers[X]
if self.keyboard[key]:
self.skip_next_instruction()
else:
self.increment_program_counter()
def op_EXA1(self, X):
key = self.registers[X]
if not self.keyboard[key]:
self.skip_next_instruction()
else:
self.increment_program_counter()
def op_FX0A(self, X):
key = self.wait_for_keypress()
self.keyboard[key] = True
self.registers[X] = key
self.increment_program_counter()
def op_FX07(self, X):
'Store the current value of the delay timer in register VX.'
self.registers[X] = self.delay_timer
self.increment_program_counter()
def op_FX15(self, X):
'Set the delay timer to the value of register VX.'
self.delay_timer = self.registers[X]
self.increment_program_counter()
def op_FX18(self, X):
'Set the sound timer to the value of register VX.'
self.sound_timer = self.registers[X]
self.increment_program_counter()
def op_FX1E(self, X):
'Add the value stored in register VX to register I.'
self.index_register += self.registers[X]
self.increment_program_counter()
def op_FX29(self, X):
'''
Set I to the memory address of the sprite data corresponding
to the hexadecimal digit stored in register VX.
'''
sprite = self.registers[X] % 16
self.index_register = self.memory.font_address(sprite)
self.increment_program_counter()
def op_FX33(self, X):
'''
Store the binary-coded decimal equivalent of the value
stored in register VX at addresses I, I+1, and I+2
Example: VX=0xFF (255); I=2, I+1=5, I+2=5
'''
data = bcd(self.registers[X])
self.memory.load(self.index_register, data)
self.increment_program_counter()
def op_F055(self, X):
'Store values of V0 to VX inclusive in mem starting at addr I.'
data = self.registers[0:X+1]
self.memory.load(self.index_register, data)
self.increment_program_counter()
def op_FX65(self, X):
'''
Fill registers V0 to VX inclusive with the values stored in
memory starting at address I
I is set to I + X + 1 after operation
'''
data = self.memory.read(self.index_register, X+1)
for R in range(X+1):
self.registers[R] = data[R]
self.increment_program_counter()
class Chip8(object):
ENTRY_POINT = 0x200
REG_COUNT = 16
KEY_COUNT = 16
def __init__(self):
self.registers = bytearray(self.REG_COUNT)
self.index_register = 0
self.program_counter = self.ENTRY_POINT
self.memory = Memory()
self.screen = Screen()
self.keyboard = bytearray(self.KEY_COUNT)
self.stack = []
self.delay_timer = 0
self.sound_timer = 0
self.INSTRUCTION_SET = {
0x00E0: self.op_00E0,
0x00EE: self.op_00EE,
0x1: self.op_1NNN,
0x2: self.op_2NNN,
0x3: self.op_3XNN,
0x4: self.op_4XNN,
0x5: self.op_5XY0,
0x6: self.op_6XNN,
0x7: self.op_7XNN,
0x8000: self.op_8XY0,
0x8001: self.op_8XY1,
0x8002: self.op_8XY2,
0x8003: self.op_8XY3,
0x8004: self.op_8XY4,
0x8005: self.op_8XY5,
0x8006: self.op_8XY6,
0x8007: self.op_8XY7,
0x800E: self.op_8XYE,
0x9000: self.op_9XY0,
0xA: self.op_ANNN,
0xB: self.op_BNNN,
0xC: self.op_CXNN,
0xD: self.op_DXYN,
0xE09E: self.op_EX9E,
0xE0A1: self.op_EXA1,
0xF007: self.op_FX07,
0xF00A: self.op_FX0A,
0xF015: self.op_FX15,
0xF018: self.op_FX18,
0xF01E: self.op_FX1E,
0xF029: self.op_FX29,
0xF033: self.op_FX33,
0xF055: self.op_F055,
0xF065: self.op_FX65,
}
def decode(self, op):
if op in [0x00E0, 0x00EE]: # special case
return (op, tuple())
instruction = I(op)
if instruction in [0x0, 0x1, 0x2, 0xA, 0xB]:
args = (NNN(op), )
elif instruction in [0x3, 0x4, 0x6, 0x7, 0xC]:
args = X(op), NN(op)
elif instruction == 0x5:
args = X(op), Y(op)
elif instruction == 0xD:
args = X(op), Y(op), N(op)
elif 0x8000 <= instruction <= 0x9000:
args = X(op), Y(op)
elif instruction >= 0xE:
args = (X(op), )
return instruction, args
def execute(self, instruction, args):
if instruction not in self.INSTRUCTION_SET:
raise NotImplementedError('{:04x} - {}'.format(instruction, args))
self.INSTRUCTION_SET.get(instruction)(*args)
def fetch(self):
return self.memory.read_word(self.program_counter)
def cycle(self):
word = self.fetch()
instruction, args = self.decode(word)
self.execute(instruction, args)
if self.delay_timer > 0:
self.delay_timer -= 1
if self.sound_timer > 0:
if self.sound_timer == 1:
self.beep()
self.sound_timer -= 1
def increment_program_counter(self):
self.program_counter += 0x2
def skip_next_instruction(self):
self.program_counter += 0x4
def wait_for_keypress(self):
raise NotImplementedError()
def beep(self):
print 'Beep!'
# INSTRUCTIONS
def op_00E0(self):
'Clear screen'
self.screen.clear()
self.increment_program_counter()
def op_00EE(self):
'Return from a subroutine.'
self.program_counter = self.stack.pop()
def op_1NNN(self, address):
'Jump to address NNN.'
self.program_counter = address
def op_2NNN(self, address):
'Execute subroutine starting at address NNN.'
self.increment_program_counter()
self.stack.append(self.program_counter)
self.program_counter = address
def op_3XNN(self, X, NN):
'Skip the following instruction if the value of VX == NN.'
if self.registers[X] == NN:
self.skip_next_instruction()
else:
self.increment_program_counter()
def op_4XNN(self, X, NN):
'Skip the following instruction if the value of VX != NN.'
if self.registers[X] != NN:
self.skip_next_instruction()
else:
self.increment_program_counter()
def op_5XY0(self, X, Y):
'Skip next instruction if the value of VX == the value of VY.'
if self.registers[X] == self.registers[Y]:
self.skip_next_instruction()
else:
self.increment_program_counter()
def op_6XNN(self, X, NN):
'Store number NN in register VX.'
self.registers[X] = NN
self.increment_program_counter()
def op_7XNN(self, X, NN):
'Add the value NN to register VX.'
self.registers[X] = byte(self.registers[X] + NN)
self.increment_program_counter()
def op_8XY0(self, X, Y):
'Store the value of register VY in register VX.'
self.registers[X] = self.registers[Y]
self.increment_program_counter()
def op_8XY1(self, X, Y):
'Set VX to VX OR VY'
self.registers[X] |= self.registers[Y]
self.increment_program_counter()
def op_8XY2(self, X, Y):
'Set VX to VX AND VY'
self.registers[X] &= self.registers[Y]
self.increment_program_counter()
def op_8XY3(self, X, Y):
'Set VX to VX XOR VY.'
self.registers[X] ^= self.registers[Y]
self.increment_program_counter()
def op_8XY4(self, X, Y):
'''Add the value of register VY to register VX
Set VF to 01 if a carry occurs
Set VF to 00 if a carry does not occur'''
value = self.registers[X] + self.registers[Y]
self.registers[X] = byte(value)
self.registers[0xF] = 1 if value > 0xFF else 0
self.increment_program_counter()
def op_8XY5(self, X, Y):
'''
Subtract the value of register VY from register VX
Set VF to 00 if a borrow occurs
Set VF to 01 if a borrow does not occur
'''
value = self.registers[X] - self.registers[Y]
self.registers[X] = byte(value)
self.registers[0xF] = 0 if value < 0 else 1
self.increment_program_counter()
def op_8XY6(self, X, Y):
'''
Store the value of register VY shifted right one bit in VX
Set VF to the least significant bit prior to the shift
'''
self.registers[X] = self.registers[Y] >> 1
self.registers[0xF] = self.registers[Y] & 1
self.increment_program_counter()
def op_8XY7(self, X, Y):
'''
Set register VX to the value of VY minus VX
Set VF to 00 if a borrow occurs
Set VF to 01 if a borrow does not occur
'''
value = self.registers[Y] - self.registers[X]
self.registers[X] = byte(value)
self.registers[0xF] = 0 if value < 0 else 1
self.increment_program_counter()
def op_8XYE(self, X, Y):
'''
Store the value of register VY shifted left one bit in VX
Set VF to the most significant bit prior to the shift
'''
self.registers[X] = byte(self.registers[Y] << 1)
self.registers[0xF] = self.registers[Y] >> 7
self.increment_program_counter()
def op_9XY0(self, X, Y):
'Skip the following instruction if the value VX != value VY.'
if self.registers[X] != self.registers[Y]:
self.skip_next_instruction()
else:
self.increment_program_counter()
def op_ANNN(self, address):
'Store memory address NNN in register I.'
self.index_register = address
self.increment_program_counter()
def op_BNNN(self, address):
'Jump to address NNN + V0.'
self.program_counter = address + self.registers[0]
def op_CXNN(self, X, NN):
'Set VX to a random number with a mask of NN.'
self.registers[X] = randint(0, 0xFF) & NN
self.increment_program_counter()
def op_DXYN(self, VX, VY, N):
x = self.registers[VX]
y = self.registers[VY]
sprite = self.memory.read(self.index_register, N)
collision = self.screen.draw(sprite, x, y)
self.registers[0xF] = bool(collision)
self.increment_program_counter()
def op_EX9E(self, X):
key = self.registers[X]
if self.keyboard[key]:
self.skip_next_instruction()
else:
self.increment_program_counter()
def op_EXA1(self, X):
key = self.registers[X]
if not self.keyboard[key]:
self.skip_next_instruction()
else:
self.increment_program_counter()
def op_FX0A(self, X):
key = self.wait_for_keypress()
self.keyboard[key] = True
self.registers[X] = key
self.increment_program_counter()
def op_FX07(self, X):
'Store the current value of the delay timer in register VX.'
self.registers[X] = self.delay_timer
self.increment_program_counter()
def op_FX15(self, X):
'Set the delay timer to the value of register VX.'
self.delay_timer = self.registers[X]
self.increment_program_counter()
def op_FX18(self, X):
'Set the sound timer to the value of register VX.'
self.sound_timer = self.registers[X]
self.increment_program_counter()
def op_FX1E(self, X):
'Add the value stored in register VX to register I.'
self.index_register += self.registers[X]
self.increment_program_counter()
def op_FX29(self, X):
'''
Set I to the memory address of the sprite data corresponding
to the hexadecimal digit stored in register VX.
'''
sprite = self.registers[X] % 16
self.index_register = self.memory.font_address(sprite)
self.increment_program_counter()
def op_FX33(self, X):
'''
Store the binary-coded decimal equivalent of the value
stored in register VX at addresses I, I+1, and I+2
Example: VX=0xFF (255); I=2, I+1=5, I+2=5
'''
data = bcd(self.registers[X])
self.memory.load(self.index_register, data)
self.increment_program_counter()
def op_F055(self, X):
'Store values of V0 to VX inclusive in mem starting at addr I.'
data = self.registers[0:X + 1]
self.memory.load(self.index_register, data)
self.increment_program_counter()
def op_FX65(self, X):
'''
Fill registers V0 to VX inclusive with the values stored in
memory starting at address I
I is set to I + X + 1 after operation
'''
data = self.memory.read(self.index_register, X + 1)
for R in range(X + 1):
self.registers[R] = data[R]
self.increment_program_counter()
