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cpu.py
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import pygame as pg
import random
USE_ORIGINAL_8XY6 = False
class CPU:
def __init__(self, game) -> None:
self.game = game
self.memory = [0] * 4096
self.v = [0] * 16
self.i = 0
self.delayTimer = 0
self.soundTimer = 0
self.pc = int(hex(0x200), base=16)
self.stack = list()
self.paused = False
self.speed = 1
def load_sprites_in_memory(self):
sprites = [
b'\xF0', b'\x90', b'\x90', b'\x90', b'\xF0', # 0
b'\x20', b'\x60', b'\x20', b'\x20', b'\x70', # 1
b'\xF0', b'\x10', b'\xF0', b'\x80', b'\xF0', # 2
b'\xF0', b'\x10', b'\xF0', b'\x10', b'\xF0', # 3
b'\x90', b'\x90', b'\xF0', b'\x10', b'\x10', # 4
b'\xF0', b'\x80', b'\xF0', b'\x10', b'\xF0', # 5
b'\xF0', b'\x80', b'\xF0', b'\x90', b'\xF0', # 6
b'\xF0', b'\x10', b'\x20', b'\x40', b'\x40', # 7
b'\xF0', b'\x90', b'\xF0', b'\x90', b'\xF0', # 8
b'\xF0', b'\x90', b'\xF0', b'\x10', b'\xF0', # 9
b'\xF0', b'\x90', b'\xF0', b'\x90', b'\x90', # A
b'\xE0', b'\x90', b'\xE0', b'\x90', b'\xE0', # B
b'\xF0', b'\x80', b'\x80', b'\x80', b'\xF0', # C
b'\xE0', b'\x90', b'\x90', b'\x90', b'\xE0', # D
b'\xF0', b'\x80', b'\xF0', b'\x80', b'\xF0', # E
b'\xF0', b'\x80', b'\xF0', b'\x80', b'\x80' # F
]
for i in range(0, len(sprites)):
self.memory[i] = int(sprites[i].hex(), base=16)
def load_rom(self, rom_name):
with open(rom_name,'rb') as rom_dump:
rom_data = rom_dump.read()
program = []
for i in range(0, len(rom_data)):
program.append(int(rom_data[i: i + 1].hex(), base=16))
for location in range(0, len(program)):
self.memory[int(hex(0x200), base=16) + location] = program[location]
def cycle(self):
for i in range(self.speed):
if not(self.paused):
opcode = (self.memory[self.pc] << 8) | self.memory[self.pc + 1] # Opcode is made by ORing two instructions together.
self.execute_instruction(opcode)
self.game.renderer.render()
def execute_instruction(self,opcode):
self.pc += 2
if opcode & 0xffff == 0x00e0: # Clear screen
self.game.renderer.clear()
elif opcode & 0xffff == 0x00ee: # Return from subroutine
self.pc = self.stack.pop()
elif opcode & 0xf000 == 0x1000: # Jump to address
address = opcode & 0x0fff
self.pc = address
elif opcode & 0xf000 == 0x2000: # Call subroutine
address = opcode & 0x0fff
self.stack.append(self.pc)
self.pc = address
elif opcode & 0xf000 == 0x3000: # Skip if v[x] == kk
x = (opcode & 0x0f00) >> 8
kk = opcode & 0x00ff
if self.v[x] == kk:
self.pc += 2
elif opcode & 0xf000 == 0x4000: # Skip if v[x] != kk
x = (opcode & 0x0f00) >> 8
kk = opcode & 0x00ff
if self.v[x] != kk:
self.pc += 2
elif opcode & 0xf00f == 0x5000: # Skip if v[x] == v[y]
x = (opcode & 0x0f00) >> 8
y = (opcode & 0x00f0) >> 4
if self.v[x] == self.v[y]:
self.pc += 2
elif opcode & 0xf000 == 0x6000: # Set v[x] == kk
x = (opcode & 0x0f00) >> 8
kk = opcode & 0x00ff
self.v[x] = kk
elif opcode & 0xf000 == 0x7000: # Add value kk to v[x]
x = (opcode & 0x0f00) >> 8
kk = opcode & 0x00ff
self.v[x] = (self.v[x] + kk) & 0xff
elif opcode & 0xf00f == 0x8000: # Set v[x] = v[y]
x = (opcode & 0x0f00) >> 8
y = (opcode & 0x00f0) >> 4
self.v[x] = self.v[y]
elif opcode & 0xf00f == 0x8001: # Bitwise OR v[x] and v[y]
x = (opcode & 0x0f00) >> 8
y = (opcode & 0x00f0) >> 4
self.v[x] |= self.v[y]
self.v[0xf] = 0
elif opcode & 0xf00f == 0x8002: # Bitwise AND v[x] and v[y]
x = (opcode & 0x0f00) >> 8
y = (opcode & 0x00f0) >> 4
self.v[x] &= self.v[y]
self.v[0xf] = 0
elif opcode & 0xf00f == 0x8003: # Bitwise XOR v[x] and v[y]
x = (opcode & 0x0f00) >> 8
y = (opcode & 0x00f0) >> 4
self.v[x] ^= self.v[y]
self.v[0xf] = 0
elif opcode & 0xf00f == 0x8004: # Add v[y] to v[x] with overflow
x = (opcode & 0x0f00) >> 8
y = (opcode & 0x00f0) >> 4
self.v[x] += self.v[y]
if self.v[x] > 0xff:
self.v[0xf] = 1
self.v[x] &= 0xff
else:
self.v[0xf] = 0
elif opcode & 0xf00f == 0x8005: # Sub v[y] from v[x] with underflow
x = (opcode & 0x0f00) >> 8
y = (opcode & 0x00f0) >> 4
vx = self.v[x]
vy = self.v[y]
self.v[x] = (vx - vy) & 0xff
if vx >= vy:
self.v[0xf] = 1
else:
self.v[0xf] = 0
elif opcode & 0xf00f == 0x8006: # Shift right
x = (opcode & 0x0f00) >> 8
y = (opcode & 0x00f0) >> 4
self.v[0xf] = self.v[y] & 0x1
self.v[x] = (self.v[y] >> 1) & 0xff
elif opcode & 0xf00f == 0x8007: # Subtract v[x] from v[y] and store in v[x]
x = (opcode & 0x0f00) >> 8
y = (opcode & 0x00f0) >> 4
self.v[x] = (self.v[y] - self.v[x]) & 0xff
if self.v[y] > self.v[x]:
self.v[0xf] = 1
else:
self.v[0xf] = 0
elif opcode & 0xf00f == 0x800e: # Shift to the left
x = (opcode & 0x0f00) >> 8
y = (opcode & 0x00f0) >> 4
self.v[0xf] = (self.v[y] & 0x80) >> 7
self.v[x] = (self.v[y] << 1) & 0xff
elif opcode & 0xf00f == 0x9000: # Skip if v[x] != v[y]
x = (opcode & 0x0f00) >> 8
y = (opcode & 0x00f0) >> 4
if self.v[x] != self.v[y]:
self.pc += 2
elif opcode & 0xf000 == 0xa000: # Set index register to nnn
address = opcode & 0x0fff
self.i = address
elif opcode & 0xf000 == 0xb000: # Jump to address with offset v[0]
address = opcode & 0x0fff
self.pc = address + self.v[0]
elif opcode & 0xf000 == 0xc000: # Set v[x] to random number
x = (opcode & 0x0f00) >> 8
kk = opcode & 0x00ff
random_num = (random.randint(0, 255)) & kk
self.v[x] = random_num
elif opcode & 0xf000 == 0xd000: # Draw instruction
x = self.v[(opcode & 0x0f00) >> 8]
y = self.v[(opcode & 0x00f0) >> 4]
self.v[0xf] = 0
n = opcode & 0x000f
# width = 8
# height = (opcode & 0xf)
# for row in range(0, height):
# sprite = self.memory[self.i + row]
# for col in range(0,width):
# if ((sprite & 0x80) > 0):
# if ((self.game.renderer.setPixel(self.v[x] + col, self.v[y] + row))):
# self.v[0xf] = 1
# sprite <<= 1
for row in range(n):
sprite_row = self.memory[self.i + row]
for bit in range(8):
pixel = (sprite_row >> (7 - bit)) & 0x01
screen_x = (x + bit) % 64
screen_y = (y + row) % 32
if pixel:
self.game.renderer.setPixel(screen_x, screen_y)
elif opcode & 0xf0ff == 0xe09e:
x = (opcode & 0x0f00) >> 8
key = self.v[x]
keys = pg.key.get_pressed()
corresponding_pg_key = None
for pg_key, chip8_key in self.game.keyboard.key_map.items():
if chip8_key == key:
corresponding_pg_key = pg_key
break
if corresponding_pg_key and keys[corresponding_pg_key]:
self.pc += 2
return
elif opcode & 0xf0ff == 0xe0a1:
x = (opcode & 0x0f00) >> 8
key = self.v[x]
keys = pg.key.get_pressed()
corresponding_pg_key = None
for pg_key, chip8_key in self.game.keyboard.key_map.items():
if chip8_key == key:
corresponding_pg_key = pg_key
break
if not corresponding_pg_key or not keys[corresponding_pg_key]:
self.pc += 2
return
elif opcode & 0xf0ff == 0xf007:
x = (opcode & 0x0f00) >> 8
self.v[x] = self.delayTimer
elif opcode & 0xf0ff == 0xf00a:
x = (opcode & 0x0f00) >> 8
keys = pg.key.get_pressed()
key_pressed = False
for pg_key, chip8_key in self.game.keyboard.key_map.items():
if keys[pg_key]:
self.v[x] = chip8_key
key_pressed = True
break
if key_pressed:
waiting_for_release = True
while waiting_for_release:
for event in pg.event.get():
if event.type == pg.KEYUP:
waiting_for_release = False
else:
self.pc -= 2
elif opcode & 0xf0ff == 0xf015:
x = (opcode & 0x0f00) >> 8
self.delayTimer = self.v[x]
elif opcode & 0xf0ff == 0xf018:
x = (opcode & 0x0f00) >> 8
self.soundTimer = v[x]
elif opcode & 0xf0ff == 0xf01e:
x = (opcode & 0x0f00) >> 8
self.i += self.v[x]
elif opcode & 0xf0ff == 0xf029:
x = (opcode & 0x0f00) >> 8
self.i = 0x50 + (self.v[x] * 5)
elif opcode & 0xf0ff == 0xf033:
x = (opcode & 0x0f00) >> 8
val = self.v[x]
hundreds = val // 100
tens = (val // 10) % 10
ones = val % 10
self.memory[self.i] = hundreds
self.memory[self.i + 1] = tens
self.memory[self.i + 2] = ones
elif opcode & 0xf0ff == 0xf055:
x = (opcode & 0x0f00) >> 8
for i in range(x + 1):
val = self.v[i]
self.memory[self.i + i] = val
self.i = self.i + x + 1
elif opcode & 0xf0ff == 0xf065:
x = (opcode & 0x0f00) >> 8
for i in range(x + 1):
val = self.memory[self.i + i]
self.v[i] = val
self.i = self.i + x + 1
else:
print(f'Instruction not handled yet, opcode: {hex(opcode)}')
if self.delayTimer > 0:
self.delayTimer -= 1
if self.soundTimer > 0:
self.soundTimer -= 1
if self.soundTimer == 0:
print("Play beep")