diff --git a/src/bus.rs b/src/bus.rs index a9f20f8..4d7d676 100644 --- a/src/bus.rs +++ b/src/bus.rs @@ -150,7 +150,7 @@ impl Bus { 0xFF24 => self.sound.control.channel.into(), 0xFF25 => self.sound.control.output.into(), 0xFF26 => self.sound.control.status.into(), - 0xFF40 => self.ppu.lcd_control.into(), + 0xFF40 => self.ppu.control.into(), 0xFF41 => self.ppu.stat.into(), 0xFF42 => self.ppu.pos.scroll_y, 0xFF43 => self.ppu.pos.scroll_x, @@ -254,7 +254,7 @@ impl Bus { 0xFF24 => self.sound.control.channel = byte.into(), 0xFF25 => self.sound.control.output = byte.into(), 0xFF26 => self.sound.control.status = byte.into(), // FIXME: Should we control which bytes are written to here? - 0xFF40 => self.ppu.lcd_control = byte.into(), + 0xFF40 => self.ppu.control = byte.into(), 0xFF41 => self.ppu.stat = byte.into(), 0xFF42 => self.ppu.pos.scroll_y = byte, 0xFF43 => self.ppu.pos.scroll_x = byte, diff --git a/src/ppu.rs b/src/ppu.rs index 76eefae..b28794e 100644 --- a/src/ppu.rs +++ b/src/ppu.rs @@ -17,7 +17,7 @@ const BLACK: [u8; 4] = [0x00, 0x00, 0x00, 0x00]; #[derive(Debug, Clone)] pub struct Ppu { pub int: Interrupt, - pub lcd_control: LCDControl, + pub control: LCDControl, pub monochrome: Monochrome, pub pos: ScreenPosition, pub vram: Box<[u8; VRAM_SIZE]>, @@ -125,16 +125,28 @@ impl Ppu { fn draw_scanline(&mut self) { let mut scanline: [u8; GB_WIDTH * 4] = [0; GB_WIDTH * 4]; + if self.control.lcd_enabled() { + self.draw_background(&mut scanline); + } + + if self.control.obj_enabled() { + self.draw_sprites(&mut scanline); + } + + let i = (GB_WIDTH * 4) * self.pos.line_y as usize; + self.frame_buf[i..(i + scanline.len())].copy_from_slice(&scanline); + } + + fn draw_background(&mut self, scanline: &mut [u8; GB_WIDTH * 4]) { let window_x = self.pos.window_x.wrapping_sub(7); // True if a window is supposed to be drawn on this scanline - let window_present = - self.lcd_control.window_enabled() && self.pos.window_y <= self.pos.line_y; + let window_present = self.control.window_enabled() && self.pos.window_y <= self.pos.line_y; let tile_map = if window_present { - self.lcd_control.win_tile_map_addr() + self.control.win_tile_map_addr() } else { - self.lcd_control.bg_tile_map_addr() + self.control.bg_tile_map_addr() }; let tile_map_addr = tile_map.into_address(); @@ -149,7 +161,7 @@ impl Ppu { // 160 / 20 = 8, so we can figure out the row of a tile with the following let tile_row = pos_y / 8; - for (i, chunk) in scanline.chunks_mut(4).enumerate() { + for (i, pixel) in scanline.chunks_mut(4).enumerate() { let line_x = i as u8; let mut pos_x = line_x.wrapping_add(self.pos.scroll_x); @@ -168,13 +180,13 @@ impl Ppu { let tile_addr = tile_map_addr + (tile_row as u16) * 32 + tile_column as u16; let tile_number = self.read_byte(tile_addr); - let tile_data_addr = match self.lcd_control.tile_data_addr() { + let tile_data_addr = match self.control.tile_data_addr() { TileDataAddress::X8800 => (0x9000_i32 + (tile_number as i32 * 16)) as u16, TileDataAddress::X8000 => 0x8000 + (tile_number as u16 * 16), }; // Find the correct vertical line we're on - let line = (pos_y % 8) * 2; // *2 since each vertical line takes up 2 bytes + let line = (pos_y % 8) * 2; // * 2 since each vertical line takes up 2 bytes let higher = self.read_byte(tile_data_addr + line as u16); let lower = self.read_byte(tile_data_addr + line as u16 + 1); @@ -184,11 +196,95 @@ impl Ppu { let palette = self.monochrome.bg_palette; let shade = palette.colour(pixels.pixel(7 - bit)); // Flip Horizontally - chunk.copy_from_slice(&shade.into_rgba()); + pixel.copy_from_slice(&shade.into_rgba()); } + } - let i = (GB_WIDTH * 4) * self.pos.line_y as usize; - self.frame_buf[i..(i + scanline.len())].copy_from_slice(&scanline); + fn draw_sprites(&mut self, scanline: &mut [u8; GB_WIDTH * 4]) { + let sprite_y_size = match self.control.obj_size() { + ObjectSize::EightByEight => 8, + ObjectSize::EightBySixteen => 16, + }; + + let mut sprite_count = 0; + + for attr_slice in self.oam.buf.chunks(4) { + // Get the Sprite Attribute information for the current Sprite we're checking + let attr_bytes: [u8; 4] = attr_slice + .try_into() + .expect("Unable to interpret &[u8] as [u8; 4]"); + let attr: SpriteAttribute = attr_bytes.into(); + + // attr.y is the sprite's vertical position + 16 + let pos_y = attr.y.wrapping_sub(16); + // attr.x is the sprite's horizontal position + 8 + let pos_x = attr.x.wrapping_sub(8); + let line_y = self.pos.line_y; + + // Do we draw the sprite? + if line_y >= pos_y && line_y < (pos_y + sprite_y_size) { + // Increase the sprite count + if sprite_count == 10 { + // Don't render any more + break; + } + + sprite_count += 1; + + // * 2 since each vertical line takes up 2 bytes + let line = if attr.flags.y_flip() { + (sprite_y_size - (line_y - pos_y)) * 2 + } else { + (line_y - pos_y) * 2 + }; + + let sprite_data_addr = 0x8000 + attr.tile_index as u16 * 16; + + let higher = self.read_byte(sprite_data_addr + line as u16); + let lower = self.read_byte(sprite_data_addr + line as u16 + 1); + let pixels = Pixels::from_bytes(higher, lower); + + let palette = match attr.flags.palette() { + SpritePaletteNumber::SpritePalette0 => self.monochrome.obj_palette_0, + SpritePaletteNumber::SpritePalette1 => self.monochrome.obj_palette_1, + }; + + let start = pos_x as usize * 4; // R, G, B, and A channels + let slice = scanline[start..(start + (4 * 8))].as_mut(); + // 4 bytes per pixel, a pixel is in 2BPP so there's 8 pixels we want to write to + + for (line_x, pixel) in slice.chunks_mut(4).enumerate() { + let bit = line_x as usize % 8; + + let id = if attr.flags.x_flip() { + pixels.pixel(bit) + } else { + pixels.pixel(7 - bit) + }; + + let maybe_shade = palette.colour(id); + + match attr.flags.priority() { + RenderPriority::Sprite => { + if let Some(shade) = maybe_shade { + pixel.copy_from_slice(&shade.into_rgba()); + } + } + RenderPriority::BackgroundAndWindow => { + if let Some(shade) = maybe_shade { + // If the colour is 1, 2 or 3 we draw over the background + match GrayShade::from_rgba(pixel) { + GrayShade::White => { + pixel.copy_from_slice(&shade.into_rgba()); + } + _ => {} // We Don't draw over the Background + } + } + } + } + } + } + } } pub fn copy_to_gui(&self, frame: &mut [u8]) { @@ -200,7 +296,7 @@ impl Default for Ppu { fn default() -> Self { Self { int: Interrupt::default(), - lcd_control: Default::default(), + control: Default::default(), monochrome: Default::default(), pos: Default::default(), stat: Default::default(), @@ -328,7 +424,7 @@ bitfield! { window_enabled, set_window_enabled: 5; from into TileDataAddress, tile_data_addr, set_tile_data_addr: 4, 4; from into TileMapAddress, bg_tile_map_addr, set_bg_tile_map_addr: 3, 3; - from into ObjectSize, obg_size, set_obj_size: 2, 2; + from into ObjectSize, obj_size, set_obj_size: 2, 2; obj_enabled, set_obj_enabled: 1; bg_win_enabled, set_bg_win_enabled: 0; } @@ -468,6 +564,20 @@ impl GrayShade { GrayShade::Black => BLACK, } } + + pub fn from_rgba(slice: &[u8]) -> Self { + let rgba: [u8; 4] = slice + .try_into() + .expect("Unable to interpret &[u8] as [u8; 4]"); + + match rgba { + WHITE => GrayShade::White, + LIGHT_GRAY => GrayShade::LightGray, + DARK_GRAY => GrayShade::DarkGray, + BLACK => GrayShade::Black, + _ => panic!("{:#04X?} is not a colour the DMG-01 supports", rgba), + } + } } impl Default for GrayShade { @@ -517,7 +627,7 @@ impl BackgroundPalette { 0b01 => self.i1_colour(), 0b10 => self.i2_colour(), 0b11 => self.i3_colour(), - _ => unreachable!("{:#04X} is not a valid colour id", id), + _ => unreachable!("{:#04X} is not a valid BG colour id", id), } } } @@ -555,6 +665,18 @@ bitfield! { pub from into GrayShade, i1_colour, set_i1_colour: 3, 2; } +impl ObjectPalette { + pub fn colour(&self, id: u8) -> Option { + match id { + 0b00 => None, + 0b01 => Some(self.i1_colour()), + 0b10 => Some(self.i2_colour()), + 0b11 => Some(self.i3_colour()), + _ => unreachable!("{:#04X} is not a valid OBJ colour id", id), + } + } +} + impl Copy for ObjectPalette {} impl Clone for ObjectPalette { fn clone(&self) -> Self { @@ -612,21 +734,6 @@ impl SpriteAttributeTable { } } -impl SpriteAttributeTable { - pub fn read_attribute(&self, addr: u16) -> SpriteAttribute { - let buf_index = (addr - 0xFE00) as usize; - self.attribute(buf_index) - } - - pub fn attribute(&self, index: usize) -> SpriteAttribute { - let bytes: [u8; 4] = self.buf[index..(index + 4)] - .try_into() - .expect("Byte slice was not four bytes in length"); - - bytes.into() - } -} - impl Default for SpriteAttributeTable { fn default() -> Self { Self { @@ -637,19 +744,19 @@ impl Default for SpriteAttributeTable { #[derive(Debug, Clone, Copy)] pub struct SpriteAttribute { - x: u8, y: u8, + x: u8, tile_index: u8, - attributes: SpriteFlag, + flags: SpriteFlag, } impl From<[u8; 4]> for SpriteAttribute { fn from(bytes: [u8; 4]) -> Self { Self { - x: bytes[0], - y: bytes[1], + y: bytes[0], + x: bytes[1], tile_index: bytes[2], - attributes: bytes[3].into(), + flags: bytes[3].into(), } } } @@ -658,10 +765,10 @@ bitfield! { pub struct SpriteFlag(u8); impl Debug; - bg_window_over_obj, set_bg_window_over_obj: 7; - from into SpriteFlip, y_flip, set_y_flip: 6, 6; - from into SpriteFlip, x_flit, set_x_flip: 5, 5; - from into BgPaletteNumber, palette, set_palette: 4, 4; + from into RenderPriority, priority, set_priority: 7, 7; + y_flip, set_y_flip: 6; + x_flip, set_x_flip: 5; + from into SpritePaletteNumber, palette, set_palette: 4, 4; } impl Copy for SpriteFlag {} @@ -682,46 +789,47 @@ impl From for u8 { flags.0 } } + #[derive(Debug, Clone, Copy)] -pub enum SpriteFlip { - Normal = 0, - HorizontalMirror = 1, +pub enum RenderPriority { + Sprite = 0, + BackgroundAndWindow = 1, } -impl From for SpriteFlip { +impl From for RenderPriority { fn from(byte: u8) -> Self { match byte { - 0b00 => SpriteFlip::Normal, - 0b01 => SpriteFlip::HorizontalMirror, - _ => unreachable!("{:#04X} is not a valid value for SpriteFlip", byte), + 0b00 => Self::Sprite, + 0b01 => Self::BackgroundAndWindow, + _ => unreachable!("{:#04X} is not a valid value for RenderPriority", byte), } } } -impl From for u8 { - fn from(flip: SpriteFlip) -> Self { - flip as u8 +impl From for u8 { + fn from(priority: RenderPriority) -> Self { + priority as u8 } } #[derive(Debug, Clone, Copy)] -pub enum BgPaletteNumber { - BgPalette0 = 0, - BgPalette1 = 1, +pub enum SpritePaletteNumber { + SpritePalette0 = 0, + SpritePalette1 = 1, } -impl From for BgPaletteNumber { +impl From for SpritePaletteNumber { fn from(byte: u8) -> Self { match byte { - 0b00 => BgPaletteNumber::BgPalette0, - 0b01 => BgPaletteNumber::BgPalette1, + 0b00 => SpritePaletteNumber::SpritePalette0, + 0b01 => SpritePaletteNumber::SpritePalette1, _ => unreachable!("{:#04X} is not a valid value for BgPaletteNumber", byte), } } } -impl From for u8 { - fn from(flip: BgPaletteNumber) -> Self { +impl From for u8 { + fn from(flip: SpritePaletteNumber) -> Self { flip as u8 } }