I am making an emulator for the chip-8 utilizing the Godot 4.3 sport engine, It is nearly full and you’ll play pong on it completely nice, However it may’t show numbers from the in-built font.
# RAM
var RAM: PackedByteArray = []
# Inbuilt font:
var font: PackedByteArray = [
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
]
func _ready() -> void:
# Different code...
# Load font into RAM:
var offset: int = 0x50
for i: int in font:
RAM[offset] = i
offset += 1
var rom: PackedByteArray = open_read_and_get_ROM("rom_path_here")
load_rom_into_ram(rom)
func load_rom_into_ram(ROM: PackedByteArray) -> void:
var offset: int = 0x200
for i: int in ROM:
RAM[offset] = i
offset += 1
chip-8 roms are supposed to make use of the font that is already in-built to your emulator, However the roms I attempt show nonsense as a substitute of displaying precise hex numbers.
I actually do not suppose there’s something mistaken with the draw instruction as a result of It may draw anything completely however right here it’s anyway:
0xD000: # 1st nibble is 'D':
# DXYN: Attracts a sprite at coordinate (VX, VY)...
registers[0xF] = 0 # VF register have to be cleared first.
var x_pos: int = registers[opcode >> 8 & 0xF] % 64
var y_pos: int = registers[opcode >> 4 & 0xF] % 32
for N: int in vary(opcode & 0x000F):
var Nth_byte: int = RAM[index_register + N]
for i: int in vary(8):
if x_pos >= 64: x_pos = x_pos % 64 # wrap coordinates when reaching finish of display screen.
display screen[x_pos][y_pos] = display screen[x_pos][y_pos] ^ (Nth_byte << i & 0b10000000)
if display screen[x_pos][y_pos] ^ (Nth_byte << i & 0b10000000) != 0: # Test if pixel collision.
registers[0xF] = 1 # add 1 to the flag register VF.
x_pos += 1
y_pos += 1
x_pos -= 8
if y_pos >= 32: y_pos = y_pos % 32 # wrap coordinates when reaching finish of display screen.
queue_redraw()
