chore(ppu): reimplement background/window/sprite priority
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123
src/ppu.rs
123
src/ppu.rs
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@ -8,7 +8,7 @@ use std::convert::TryInto;
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pub(crate) use types::PpuMode;
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use types::{
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BackgroundPalette, GrayShade, LCDControl, LCDStatus, ObjectFlags, ObjectPalette,
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ObjectPaletteId, ObjectSize, Pixels, RenderPriority, TileDataAddress,
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ObjectPaletteKind, ObjectSize, Pixels, RenderPriority, TileDataAddress,
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};
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mod dma;
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@ -47,7 +47,7 @@ pub struct Ppu {
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pub(crate) dma: DirectMemoryAccess,
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scan_state: OamScanState,
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fetch: PixelFetcher,
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fifo: FifoRenderer,
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fifo: PixelFifo,
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obj_buffer: ObjectBuffer,
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frame_buf: Box<[u8; GB_WIDTH * GB_HEIGHT * 4]>,
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window_stat: WindowStatus,
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@ -282,10 +282,7 @@ impl Ppu {
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let tbpp = Pixels::from_bytes(high, low);
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let palette = match attr.flags.palette() {
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ObjectPaletteId::Zero => self.monochrome.obj_palette_0,
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ObjectPaletteId::One => self.monochrome.obj_palette_1,
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};
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let palette_kind = attr.flags.palette();
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let end = Pixels::PIXEL_COUNT - self.fifo.obj.len();
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let start = Pixels::PIXEL_COUNT - end;
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@ -296,11 +293,11 @@ impl Ppu {
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let x = if x_flip { 7 - i } else { i };
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let priority = attr.flags.priority();
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let shade = palette.shade(tbpp.shade_id(x));
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let shade_id = tbpp.shade_id(x);
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let fifo_info = ObjectFifoInfo {
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shade,
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palette,
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let fifo_info = ObjPixelProperty {
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shade_id,
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palette_kind,
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priority,
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};
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@ -368,9 +365,7 @@ impl Ppu {
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self.fetch.back.next(SendToFifoTwo);
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}
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SendToFifoTwo => {
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let palette = &self.monochrome.bg_palette;
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if let Ok(()) = self.fetch.send_to_fifo(&mut self.fifo, palette) {
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if let Ok(()) = self.fetch.send_to_fifo(&mut self.fifo) {
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self.fetch.x_pos += 1;
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self.fetch.back.next(TileNumber);
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self.fetch.back.tile = Default::default();
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@ -380,8 +375,6 @@ impl Ppu {
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}
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if self.fifo.is_enabled() {
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use RenderPriority::*;
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if self.x_pos == 0 && !self.fifo.back.is_empty() {
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let to_discard = self.pos.scroll_x % 8;
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@ -391,39 +384,12 @@ impl Ppu {
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}
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// Handle Background Pixel and Sprite FIFO
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let bg_enabled = self.ctrl.bg_win_enabled();
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let obj_enabled = self.ctrl.obj_enabled();
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let i0_colour = self.monochrome.bg_palette.i0_colour();
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// FIXME: Is this the correct behaviour
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let rgba_opt = self.fifo.back.pop_front().map(|bg_info| {
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let bg_shade = if bg_enabled { bg_info.shade } else { i0_colour };
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match self.fifo.obj.pop_front() {
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Some(obj_info) => {
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if obj_enabled {
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match (obj_info.shade, obj_info.priority) {
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(Some(obj_shade), BackgroundAndWindow) => match bg_info.shade {
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GrayShade::White => obj_shade.into_rgba(),
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_ => bg_shade.into_rgba(),
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},
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(Some(obj_shade), Object) => obj_shade.into_rgba(),
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(None, _) => bg_shade.into_rgba(),
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}
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} else {
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bg_shade.into_rgba()
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}
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}
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None => bg_shade.into_rgba(),
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}
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});
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if let Some(rgba) = rgba_opt.as_ref() {
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if let Some(rgba) = self.clock_fifo().map(GrayShade::into_rgba) {
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let y = self.pos.line_y as usize;
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let x = self.x_pos as usize;
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let i = (GB_WIDTH * 4) * y + (x * 4);
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self.frame_buf[i..(i + rgba.len())].copy_from_slice(rgba);
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self.frame_buf[i..(i + rgba.len())].copy_from_slice(&rgba);
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self.x_pos += 1;
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}
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@ -442,6 +408,49 @@ impl Ppu {
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pub fn copy_to_gui(&self, frame: &mut [u8]) {
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frame.copy_from_slice(self.frame_buf.as_ref());
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}
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fn clock_fifo(&mut self) -> Option<GrayShade> {
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use ObjectPaletteKind::*;
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use RenderPriority::*;
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let obj_palette_0 = &self.monochrome.obj_palette_0;
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let obj_palette_1 = &self.monochrome.obj_palette_1;
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match self.fifo.back.pop_front() {
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Some(bg_pixel) => match self.fifo.obj.pop_front() {
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Some(obj_pixel) if self.ctrl.obj_enabled() => match obj_pixel.priority {
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Object | BackgroundAndWindow if obj_pixel.shade_id == 0 => {
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Some(self.bg_pixel(bg_pixel.shade_id))
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}
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BackgroundAndWindow if bg_pixel.shade_id != 0 => {
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Some(self.bg_pixel(bg_pixel.shade_id))
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}
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Object | BackgroundAndWindow => {
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let maybe_sprite = match obj_pixel.palette_kind {
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Zero => obj_palette_0.shade(obj_pixel.shade_id),
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One => obj_palette_1.shade(obj_pixel.shade_id),
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};
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let sprite = maybe_sprite
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.expect("Sprite w/ a colour id of 0 has already been handled");
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Some(sprite)
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}
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},
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_ => Some(self.bg_pixel(bg_pixel.shade_id)),
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},
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None => None,
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}
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}
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fn bg_pixel(&self, shade_id: u8) -> GrayShade {
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let bg_palette = &self.monochrome.bg_palette;
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if self.ctrl.bg_win_enabled() {
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bg_palette.shade(shade_id)
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} else {
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bg_palette.shade(0)
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}
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}
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}
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impl Default for Ppu {
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@ -721,7 +730,7 @@ impl PixelFetcher {
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tile_data_addr + (offset * 2)
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}
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fn send_to_fifo(&self, fifo: &mut FifoRenderer, palette: &BackgroundPalette) -> Result<(), ()> {
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fn send_to_fifo(&self, fifo: &mut PixelFifo) -> Result<(), ()> {
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if !fifo.back.is_empty() {
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return Err(());
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}
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@ -735,9 +744,9 @@ impl PixelFetcher {
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let tbpp = Pixels::from_bytes(high, low);
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for x in 0..Pixels::PIXEL_COUNT {
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let shade = palette.shade(tbpp.shade_id(x));
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let shade_id = tbpp.shade_id(x);
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let fifo_info = BackgroundFifoInfo { shade };
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let fifo_info = BgPixelProperty { shade_id };
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fifo.back.push_back(fifo_info);
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}
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@ -897,27 +906,27 @@ impl Default for FetcherState {
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}
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#[derive(Debug, Clone, Copy, Default)]
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struct BackgroundFifoInfo {
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shade: GrayShade,
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struct BgPixelProperty {
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shade_id: u8,
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}
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#[derive(Debug, Clone, Copy, Default)]
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struct ObjectFifoInfo {
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shade: Option<GrayShade>,
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palette: ObjectPalette,
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struct ObjPixelProperty {
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shade_id: u8,
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palette_kind: ObjectPaletteKind,
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priority: RenderPriority,
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}
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// FIXME: Fifo Registers have a known size. Are heap allocations
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// really necessary here?
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#[derive(Debug, Clone)]
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struct FifoRenderer {
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back: VecDeque<BackgroundFifoInfo>,
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obj: VecDeque<ObjectFifoInfo>,
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struct PixelFifo {
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back: VecDeque<BgPixelProperty>,
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obj: VecDeque<ObjPixelProperty>,
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enabled: bool,
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}
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impl FifoRenderer {
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impl PixelFifo {
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fn is_enabled(&self) -> bool {
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self.enabled
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}
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@ -931,7 +940,7 @@ impl FifoRenderer {
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}
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}
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impl Default for FifoRenderer {
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impl Default for PixelFifo {
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fn default() -> Self {
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Self {
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back: VecDeque::with_capacity(8),
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@ -332,7 +332,7 @@ bitfield! {
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pub from into RenderPriority, priority, set_priority: 7, 7;
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pub y_flip, set_y_flip: 6;
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pub x_flip, set_x_flip: 5;
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pub from into ObjectPaletteId, palette, set_palette: 4, 4;
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pub from into ObjectPaletteKind, palette, set_palette: 4, 4;
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}
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impl Eq for ObjectFlags {}
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@ -368,23 +368,29 @@ impl Default for ObjectFlags {
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}
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#[derive(Debug, Clone, Copy)]
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pub enum ObjectPaletteId {
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pub enum ObjectPaletteKind {
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Zero = 0,
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One = 1,
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}
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impl From<u8> for ObjectPaletteId {
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impl Default for ObjectPaletteKind {
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fn default() -> Self {
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Self::Zero
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}
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}
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impl From<u8> for ObjectPaletteKind {
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fn from(byte: u8) -> Self {
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match byte & 0b01 {
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0b00 => ObjectPaletteId::Zero,
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0b01 => ObjectPaletteId::One,
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0b00 => ObjectPaletteKind::Zero,
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0b01 => ObjectPaletteKind::One,
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_ => unreachable!("{:#04X} is not a valid value for BgPaletteNumber", byte),
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}
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}
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}
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impl From<ObjectPaletteId> for u8 {
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fn from(palette_num: ObjectPaletteId) -> Self {
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impl From<ObjectPaletteKind> for u8 {
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fn from(palette_num: ObjectPaletteKind) -> Self {
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palette_num as u8
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}
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}
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