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chip8.py.bak
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chip8.py.bak
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import pdb
import io
import json
import pyxel
import random
# https://tobiasvl.github.io/blog/write-a-chip-8-emulator/
# https://austinmorlan.com/posts/chip8_emulator/#the-instructions
SCREEN_WIDTH = 64
SCREEN_HEIGHT = 32
SCREEN_COLOR_OFF = 5
SCREEN_COLOR_ON = 1
ROM_STARTING_ADDRESS = 0x200
FONT_STARTING_ADDRESS = 0x50
VM_INSTRUCTIONS_PER_SECOND = 700
VM_ROMS_FOLDER = "roms/"
VM_MEMORY_SIZE = 4096
FONT_DATA = [
0xF0, 0x90, 0x90, 0x90, 0xF0, # 0
0x20, 0x60, 0x20, 0x20, 0x70, # 1
0xF0, 0x10, 0xF0, 0x80, 0xF0, # 2
0xF0, 0x10, 0xF0, 0x10, 0xF0, # 3
0x90, 0x90, 0xF0, 0x10, 0x10, # 4
0xF0, 0x80, 0xF0, 0x10, 0xF0, # 5
0xF0, 0x80, 0xF0, 0x90, 0xF0, # 6
0xF0, 0x10, 0x20, 0x40, 0x40, # 7
0xF0, 0x90, 0xF0, 0x90, 0xF0, # 8
0xF0, 0x90, 0xF0, 0x10, 0xF0, # 9
0xF0, 0x90, 0xF0, 0x90, 0x90, # A
0xE0, 0x90, 0xE0, 0x90, 0xE0, # B
0xF0, 0x80, 0x80, 0x80, 0xF0, # C
0xE0, 0x90, 0x90, 0x90, 0xE0, # D
0xF0, 0x80, 0xF0, 0x80, 0xF0, # E
0xF0, 0x80, 0xF0, 0x80, 0x80 # F
]
class Chip8VM:
def __init__(self):
# program counter to the current instruction in memory. (12 bits addressable)
self.PC = ROM_STARTING_ADDRESS
# 16-bit register to point to locations in mem. (12 bits addressable)
self.I = 0
self.stack = []
# 8-bit delay timer.
self.delay = 0
# 8-bit sound timer.
self.sound = 0
# 16 8-bit general purpose registers. (V0-VF where VF is a flag register)
self.V = [0] * 16
# 4kb (4096 bytes to be exact), memory must be writable.
# Load ROM's (which can self modify technically) into address 0x200.
self.memory = [0] * VM_MEMORY_SIZE
pyxel.init(SCREEN_WIDTH, SCREEN_HEIGHT, title="Hello Pyxel")
#pyxel.image(0).load(0, 0, "assets/pyxel_logo_38x16.png")
self.start()
def start(self):
self.install_fonts()
self.load_rom("roms/IBM Logo.ch8")
pyxel.run(self.update, self.draw)
def stop(self):
pass
def update(self):
if pyxel.btnp(pyxel.KEY_Q):
pyxel.quit()
if self.delay > 0:
self.delay -=1
if self.sound > 0:
self.sound -=1
self.tick()
def draw(self):
pass
#for (m, x) in enumerate(self.data["foo"]):
# pyxel.text(20, 41 + (m * 15), x, pyxel.frame_count % 16)
#pdb.set_trace()
#pyxel.cls(0)
#for i in range(100):
# pyxel.pset(random.randint(0,160), random.randint(0,120), random.randint(0,15))
#pyxel.text(55, 41, "Hello, Pyxel!", pyxel.frame_count % 16)
#pyxel.blt(61, 66, 0, 0, 0, 38, 16)
# Resets the entire Chip8 VM state.
def reset_vm(self):
pass
def install_fonts(self):
for i, b in enumerate(FONT_DATA):
self.memory[FONT_STARTING_ADDRESS + i] = b
# Loads a rom from disk into memory at the appropriate offset.
def load_rom(self, rom_file):
with io.open(rom_file, 'rb') as f:
rom_data = f.read()
counter = 0
for b in rom_data:
self.memory[ROM_STARTING_ADDRESS + counter] = b
counter +=1
# Performs one cycle.
def tick(self):
inst = self.fetch()
self.decode_and_execute(inst)
def fetch(self):
inst_16_bit = self.memory[self.PC] << 8 | self.memory[self.PC+1]
self.PC = self.PC + 2
return inst_16_bit
def push(self, val):
self.stack.append(val)
def pop(self):
self.stack.pop()
def decode_and_execute(self, inst):
inst_category = inst & 0xF000
if inst_category == 0x0000:
if inst == 0x00E0:
# clear screen
print("inst: clear screen")
pyxel.cls(SCREEN_COLOR_OFF)
elif inst == 0x00EE:
print("inst: return from sub")
return_addr = self.pop()
self.PC = return_addr
elif inst_category == 0x1000:
#print("inst: jump")
self.PC = inst & 0x0FFF
elif inst_category == 0x2000:
print("inst: call subroutine")
self.push(self.PC)
self.PC = inst & 0xFFF
elif inst_category == 0x3000:
if self.V[(inst & 0x0F00) >> 8] == inst & 0x0FF:
print("inst: if VX == NN skip 1 instruction")
self.PC = self.PC + 2
elif inst_category == 0x4000:
if self.V[(inst & 0x0F00) >> 8] != inst & 0x0FF:
print("inst: if VX != NN skip 1 instruction")
self.PC = self.PC + 2
elif inst_category == 0x5000:
if self.V[(inst & 0x0F00) >> 8] == self.V[(inst & 0x00F0) >> 4]:
print("inst: if VX == VY skip 1 instruction")
self.PC = self.PC + 2
elif inst_category == 0x6000:
self.V[(inst & 0x0F00) >> 8] = inst & 0x00FF
print("inst: set register VX to the value NN")
elif inst_category == 0x7000:
print("inst: add value to register VX")
self.V[(inst & 0x0F00) >> 8] += inst & 0x00FF
elif inst_category == 0x8000:
print("inst: set/or/and/xor/add arithmetic")
inst_subcategory = inst & 0x000F
if inst_subcategory == 0:
self.V[(inst & 0x0F00) >> 8] = self.V[(inst & 0x00F0) >> 4]
elif inst_subcategory == 1:
self.V[(inst & 0x0F00) >> 8] = self.V[(inst & 0x0F00) >> 8] | self.V[(inst & 0x00F0) >> 4]
elif inst_subcategory == 2:
self.V[(inst & 0x0F00) >> 8] = self.V[(inst & 0x0F00) >> 8] & self.V[(inst & 0x00F0) >> 4]
elif inst_subcategory == 3:
self.V[(inst & 0x0F00) >> 8] = self.V[(inst & 0x0F00) >> 8] ^ self.V[(inst & 0x00F0) >> 4]
elif inst_subcategory == 4:
self.V[(inst & 0x0F00) >> 8] = self.V[(inst & 0x0F00) >> 8] + self.V[(inst & 0x00F0) >> 4]
# This instruction handles overflow.
if self.V[(inst & 0x0F00) >> 8] > 255:
self.V[0xF] = 1
else:
self.V[0xF] = 0
elif inst_subcategory == 5:
self.V[(inst & 0x0F00) >> 8] = self.V[(inst & 0x0F00) >> 8] - self.V[(inst & 0x00F0) >> 4]
# TODO: handle weird underflow logic bruh!!!
elif inst_subcategory == 6:
pass
elif inst_category == 0x9000:
if self.V[(inst & 0x0F00) >> 8] != self.V[(inst & 0x00F0) >> 4]:
print("inst: if VX != VY skip 1 instruction")
self.PC = self.PC + 2
elif inst_category == 0xA000:
self.I = inst & 0x0FFF
print("inst: set register I to the value NNN")
elif inst_category == 0xB000:
print("inst: jump to offset: ambiguous instruction utilizing primary implementation")
self.PC = self.V[0x0] + (inst & 0x0FFF)
elif inst_category == 0xC000:
print("inst: random")
self.V[(inst & 0x0F00) >> 8] = random.randint(0, 100) & (inst & 0x0FF)
elif inst_category == 0xD000:
print("inst: display/draw")
vX = (inst & 0xF00) >> 8
vY = (inst & 0xF0) >> 4
height = (inst & 0xF)
# Modulus ensures we handle "wrap-around" drawing.
xPos = self.V[vX] % SCREEN_WIDTH
yPos = self.V[vY] % SCREEN_HEIGHT
self.V[0xF] = 0
for row in range(height):
spriteByte = self.memory[self.I + row]
for col in range(8):
spritePix = spriteByte & (0x80 >> col)
screenPix = pyxel.pget(xPos + col, yPos + row)
if spritePix:
if screenPix == 0xF:
self.V[0xF] = 0
pyxel.pset(xPos + col, yPos + row, SCREEN_COLOR_ON)
elif inst_category == 0xE000:
print("inst: ??")
elif inst_category == 0xF000:
print("inst: ??")
Chip8VM()