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WIP PPU CGB support

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This commit is contained in:
Franco Colmenarez 2021-12-23 19:40:25 -05:00
parent c109346dcf
commit 3f2824714f
2 changed files with 105 additions and 20 deletions
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6
src/bus.rs
View File

@ -62,7 +62,7 @@ impl Bus {
true => Box::new(CGBRAM::new()),
false => Box::new(DMGRAM::new()),
},
ppu: PPU::new(),
ppu: PPU::new(cgb_mode),
joypad: Joypad::new(),
timer: Timer::new(),
sound: Sound::new(),
@ -105,7 +105,7 @@ impl Bus {
} else if address == INTERRUPT_ENABLE_ADDRESS || address == INTERRUPT_FLAG_ADDRESS {
return self.interrupts.read(address);
} else if VIDEO_RAM.contains(&address) {
return self.ppu.read_vram(address);
return self.ppu.read_vram_external(address);
} else if SPRITE_ATTRIBUTE_TABLE.contains(&address) {
return self.ppu.read_oam(address);
} else if PPU::is_io_register(address) {
@ -147,7 +147,7 @@ impl Bus {
let byte = self.data[address as usize];
self.data[address as usize] = (data & 0b11110000) | (byte & 0b00001111);
} else if VIDEO_RAM.contains(&address) {
return self.ppu.write_vram(address, data);
return self.ppu.write_vram_external(address, data);
} else if SPRITE_ATTRIBUTE_TABLE.contains(&address) {
return self.ppu.write_oam(address, data);
} else if address == DMA_ADDRESS {

115
src/ppu.rs
View File

@ -26,6 +26,7 @@ pub const OBJECT_PALETTE_0_ADDRESS: u16 = 0xFF48;
pub const OBJECT_PALETTE_1_ADDRESS: u16 = 0xFF49;
pub const WINDOW_Y_ADDRESS: u16 = 0xFF4A;
pub const WINDOW_X_ADDRESS: u16 = 0xFF4B;
pub const VRAM_BANK_SELECT_ADDRESS: u16 = 0xFF4F;
pub const TILE_MAP_ADDRESS: u16 = 0x9800;
@ -126,6 +127,26 @@ pub enum LCDStatus {
ModeFlag(LCDStatusModeFlag),
}
struct BgAttributes {
bg_to_oam_priority: bool,
vertical_flip: bool,
horizontal_flip: bool,
vram_bank: u8,
palette_number: u8,
}
impl BgAttributes {
pub fn new(byte: u8) -> Self {
Self {
bg_to_oam_priority: get_bit(byte, BitIndex::I7),
vertical_flip: get_bit(byte, BitIndex::I6),
horizontal_flip: get_bit(byte, BitIndex::I5),
vram_bank: get_bit(byte, BitIndex::I3) as u8,
palette_number: byte & 0b111,
}
}
}
struct Sprite {
x: u8,
y: u8,
@ -136,6 +157,8 @@ struct Sprite {
y_flip: bool,
over_bg: bool,
bit_pixels: Option<[u8; 8]>,
vram_bank: u8,
palette_number: u8,
}
impl Sprite {
@ -229,13 +252,15 @@ pub struct PPU {
scroll_y: u8,
window_x: u8,
window_y: u8,
io_registers: [u8; 12],
vram: [u8; 0x2000],
io_registers: [u8; 16],
vram: [u8; 0x2000 * 2],
oam: [u8; 0xA0],
vram_bank: u8,
cgb_mode: bool,
}
impl PPU {
pub fn new() -> Self {
pub fn new(cgb_mode: bool) -> Self {
Self {
state: false,
background_priority: false,
@ -256,21 +281,41 @@ impl PPU {
scroll_y: 0,
window_x: 0,
window_y: 0,
io_registers: [0; 12],
vram: [0; 0x2000],
io_registers: [0; 16],
vram: [0; 0x2000 * 2],
oam: [0; 0xA0],
vram_bank: 0,
cgb_mode,
}
}
pub fn set_vram_bank(&mut self, bank: u8) {
if self.cgb_mode {
self.vram_bank = bank & 1;
}
}
pub fn get_vram_bank(&self) -> u8 {
self.vram_bank | 0xFE
}
pub fn is_io_register(address: u16) -> bool {
address >= 0xFF40 && address <= 0xFF4B
address >= 0xFF40 && address <= 0xFF4F
}
pub fn read_vram(&self, address: u16) -> u8 {
pub fn read_vram_external(&self, address: u16) -> u8 {
self.vram[((address + (0x2000 * self.vram_bank as u16)) - 0x8000) as usize]
}
pub fn write_vram_external(&mut self, address: u16, data: u8) {
self.vram[((address + (0x2000 * self.vram_bank as u16)) - 0x8000) as usize] = data;
}
fn read_vram(&self, address: u16) -> u8 {
self.vram[(address - 0x8000) as usize]
}
pub fn write_vram(&mut self, address: u16, data: u8) {
fn write_vram(&mut self, address: u16, data: u8) {
self.vram[(address - 0x8000) as usize] = data;
}
@ -283,7 +328,9 @@ impl PPU {
}
pub fn get_register(&self, address: u16) -> u8 {
if address == LCD_CONTROL_ADDRESS {
if address == VRAM_BANK_SELECT_ADDRESS {
return self.get_vram_bank();
} else if address == LCD_CONTROL_ADDRESS {
return self.lcd_control;
} else if address == LCD_Y_ADDRESS {
return self.lcd_y;
@ -292,7 +339,9 @@ impl PPU {
}
pub fn set_register(&mut self, address: u16, data: u8) {
if address == LCD_Y_ADDRESS {
if address == VRAM_BANK_SELECT_ADDRESS {
return self.set_vram_bank(data);
} else if address == LCD_Y_ADDRESS {
return;
} else if address == LCD_CONTROL_ADDRESS {
self.lcd_control = data;
@ -465,12 +514,19 @@ impl PPU {
y_flip: get_bit(attributes, BitIndex::I6),
over_bg: get_bit(attributes, BitIndex::I7),
bit_pixels: None,
vram_bank: match self.cgb_mode && get_bit(attributes, BitIndex::I3) {
true => 1,
false => 0,
},
palette_number: attributes & 0b111,
});
addr += 4;
}
if !self.cgb_mode {
self.sprite_buffer.sort_by(|a, b| a.x().cmp(&b.x()));
}
}
fn find_sprite_pixel(&mut self) -> Option<(Pixel, bool)> {
let lcd_y = self.lcd_y;
@ -522,12 +578,17 @@ impl PPU {
self.force_set_register(LCD_STATUS_ADDRESS, byte);
}
fn get_tile_bytes(&self, x: u8, y: u8, tilemap_area: u16, default_method: bool) -> (u8, u8) {
fn get_tile_bytes(&self, x: u8, y: u8, tilemap_area: u16, default_method: bool) -> (u8, u8, BgAttributes) {
let index_x = x as u16 / 8;
let index_y = (y as u16 / 8) * 32;
let index = index_x + index_y;
let tile_line = (y).rem_euclid(8) * 2;
let tile_number = self.read_vram(tilemap_area + index as u16) as u16;
let mut tile_line = (y).rem_euclid(8);
let attributes = BgAttributes::new(self.read_vram(tilemap_area + 0x2000 + index as u16));
if self.cgb_mode && attributes.vertical_flip {
tile_line = 7 - tile_line;
}
tile_line = tile_line * 2;
let addr = if default_method {
0x8000 + tile_line as u16 + (tile_number * 16)
} else {
@ -537,7 +598,31 @@ impl PPU {
(base + tile_line + (tile_number * 16)) as u16
};
(self.read_vram(addr), self.read_vram(addr + 1))
if !self.cgb_mode {
return (self.read_vram(addr), self.read_vram(addr + 1), attributes);
}
let byte1 = self.read_vram(addr + (0x2000 * (attributes.vram_bank as u16)));
let byte2 = self.read_vram(addr + (0x2000 * (attributes.vram_bank as u16)) + 1);
if attributes.horizontal_flip {
let byte1 = ((byte1 >> 7) & 0b1) |
((byte1 >> 5) & 0b10) |
((byte1 >> 3) & 0b100) |
((byte1 >> 1) & 0b1000) |
((byte1 << 1) & 0b10000) |
((byte1 << 3) & 0b100000) |
((byte1 << 5) & 0b1000000) |
((byte1 << 7) & 0b10000000);
let byte2 = ((byte2 >> 7) & 0b1) |
((byte2 >> 5) & 0b10) |
((byte2 >> 3) & 0b100) |
((byte2 >> 1) & 0b1000) |
((byte2 << 1) & 0b10000) |
((byte2 << 3) & 0b100000) |
((byte2 << 5) & 0b1000000) |
((byte2 << 7) & 0b10000000);
return (byte1, byte2, attributes);
}
return (byte1, byte2, attributes);
}
fn get_window_pixel(&mut self) -> Option<Pixel> {
@ -577,7 +662,7 @@ impl PPU {
true => 0x9C00,
false => 0x9800,
};
let (tile_byte_1, tile_byte_2) = self.get_tile_bytes(x, y, tilemap_area, default_mode);
let (tile_byte_1, tile_byte_2, _) = self.get_tile_bytes(x, y, tilemap_area, default_mode);
let bit_pixels_array = PPU::get_byte_pixels(tile_byte_1, tile_byte_2);
self.current_window_pixels = Some(bit_pixels_array);
@ -614,7 +699,7 @@ impl PPU {
true => 0x9C00,
false => 0x9800,
};
let (tile_byte_1, tile_byte_2) = self.get_tile_bytes(x, y, tilemap_area, default_mode);
let (tile_byte_1, tile_byte_2, _) = self.get_tile_bytes(x, y, tilemap_area, default_mode);
let bit_pixels_array = PPU::get_byte_pixels(tile_byte_1, tile_byte_2);
self.current_background_pixels = Some(bit_pixels_array);