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chore(ppu): reimplement background/window/sprite priority

This commit is contained in:
Rekai Nyangadzayi Musuka 2021-07-15 22:29:51 -05:00
parent b9a798d0ad
commit fd9a5b51ba
2 changed files with 79 additions and 64 deletions
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123
src/ppu.rs
View File

@ -8,7 +8,7 @@ use std::convert::TryInto;
pub(crate) use types::PpuMode;
use types::{
BackgroundPalette, GrayShade, LCDControl, LCDStatus, ObjectFlags, ObjectPalette,
ObjectPaletteId, ObjectSize, Pixels, RenderPriority, TileDataAddress,
ObjectPaletteKind, ObjectSize, Pixels, RenderPriority, TileDataAddress,
};
mod dma;
@ -47,7 +47,7 @@ pub struct Ppu {
pub(crate) dma: DirectMemoryAccess,
scan_state: OamScanState,
fetch: PixelFetcher,
fifo: FifoRenderer,
fifo: PixelFifo,
obj_buffer: ObjectBuffer,
frame_buf: Box<[u8; GB_WIDTH * GB_HEIGHT * 4]>,
window_stat: WindowStatus,
@ -282,10 +282,7 @@ impl Ppu {
let tbpp = Pixels::from_bytes(high, low);
let palette = match attr.flags.palette() {
ObjectPaletteId::Zero => self.monochrome.obj_palette_0,
ObjectPaletteId::One => self.monochrome.obj_palette_1,
};
let palette_kind = attr.flags.palette();
let end = Pixels::PIXEL_COUNT - self.fifo.obj.len();
let start = Pixels::PIXEL_COUNT - end;
@ -296,11 +293,11 @@ impl Ppu {
let x = if x_flip { 7 - i } else { i };
let priority = attr.flags.priority();
let shade = palette.shade(tbpp.shade_id(x));
let shade_id = tbpp.shade_id(x);
let fifo_info = ObjectFifoInfo {
shade,
palette,
let fifo_info = ObjPixelProperty {
shade_id,
palette_kind,
priority,
};
@ -368,9 +365,7 @@ impl Ppu {
self.fetch.back.next(SendToFifoTwo);
}
SendToFifoTwo => {
let palette = &self.monochrome.bg_palette;
if let Ok(()) = self.fetch.send_to_fifo(&mut self.fifo, palette) {
if let Ok(()) = self.fetch.send_to_fifo(&mut self.fifo) {
self.fetch.x_pos += 1;
self.fetch.back.next(TileNumber);
self.fetch.back.tile = Default::default();
@ -380,8 +375,6 @@ impl Ppu {
}
if self.fifo.is_enabled() {
use RenderPriority::*;
if self.x_pos == 0 && !self.fifo.back.is_empty() {
let to_discard = self.pos.scroll_x % 8;
@ -391,39 +384,12 @@ impl Ppu {
}
// Handle Background Pixel and Sprite FIFO
let bg_enabled = self.ctrl.bg_win_enabled();
let obj_enabled = self.ctrl.obj_enabled();
let i0_colour = self.monochrome.bg_palette.i0_colour();
// FIXME: Is this the correct behaviour
let rgba_opt = self.fifo.back.pop_front().map(|bg_info| {
let bg_shade = if bg_enabled { bg_info.shade } else { i0_colour };
match self.fifo.obj.pop_front() {
Some(obj_info) => {
if obj_enabled {
match (obj_info.shade, obj_info.priority) {
(Some(obj_shade), BackgroundAndWindow) => match bg_info.shade {
GrayShade::White => obj_shade.into_rgba(),
_ => bg_shade.into_rgba(),
},
(Some(obj_shade), Object) => obj_shade.into_rgba(),
(None, _) => bg_shade.into_rgba(),
}
} else {
bg_shade.into_rgba()
}
}
None => bg_shade.into_rgba(),
}
});
if let Some(rgba) = rgba_opt.as_ref() {
if let Some(rgba) = self.clock_fifo().map(GrayShade::into_rgba) {
let y = self.pos.line_y as usize;
let x = self.x_pos as usize;
let i = (GB_WIDTH * 4) * y + (x * 4);
self.frame_buf[i..(i + rgba.len())].copy_from_slice(rgba);
self.frame_buf[i..(i + rgba.len())].copy_from_slice(&rgba);
self.x_pos += 1;
}
@ -442,6 +408,49 @@ impl Ppu {
pub fn copy_to_gui(&self, frame: &mut [u8]) {
frame.copy_from_slice(self.frame_buf.as_ref());
}
fn clock_fifo(&mut self) -> Option<GrayShade> {
use ObjectPaletteKind::*;
use RenderPriority::*;
let obj_palette_0 = &self.monochrome.obj_palette_0;
let obj_palette_1 = &self.monochrome.obj_palette_1;
match self.fifo.back.pop_front() {
Some(bg_pixel) => match self.fifo.obj.pop_front() {
Some(obj_pixel) if self.ctrl.obj_enabled() => match obj_pixel.priority {
Object | BackgroundAndWindow if obj_pixel.shade_id == 0 => {
Some(self.bg_pixel(bg_pixel.shade_id))
}
BackgroundAndWindow if bg_pixel.shade_id != 0 => {
Some(self.bg_pixel(bg_pixel.shade_id))
}
Object | BackgroundAndWindow => {
let maybe_sprite = match obj_pixel.palette_kind {
Zero => obj_palette_0.shade(obj_pixel.shade_id),
One => obj_palette_1.shade(obj_pixel.shade_id),
};
let sprite = maybe_sprite
.expect("Sprite w/ a colour id of 0 has already been handled");
Some(sprite)
}
},
_ => Some(self.bg_pixel(bg_pixel.shade_id)),
},
None => None,
}
}
fn bg_pixel(&self, shade_id: u8) -> GrayShade {
let bg_palette = &self.monochrome.bg_palette;
if self.ctrl.bg_win_enabled() {
bg_palette.shade(shade_id)
} else {
bg_palette.shade(0)
}
}
}
impl Default for Ppu {
@ -721,7 +730,7 @@ impl PixelFetcher {
tile_data_addr + (offset * 2)
}
fn send_to_fifo(&self, fifo: &mut FifoRenderer, palette: &BackgroundPalette) -> Result<(), ()> {
fn send_to_fifo(&self, fifo: &mut PixelFifo) -> Result<(), ()> {
if !fifo.back.is_empty() {
return Err(());
}
@ -735,9 +744,9 @@ impl PixelFetcher {
let tbpp = Pixels::from_bytes(high, low);
for x in 0..Pixels::PIXEL_COUNT {
let shade = palette.shade(tbpp.shade_id(x));
let shade_id = tbpp.shade_id(x);
let fifo_info = BackgroundFifoInfo { shade };
let fifo_info = BgPixelProperty { shade_id };
fifo.back.push_back(fifo_info);
}
@ -897,27 +906,27 @@ impl Default for FetcherState {
}
#[derive(Debug, Clone, Copy, Default)]
struct BackgroundFifoInfo {
shade: GrayShade,
struct BgPixelProperty {
shade_id: u8,
}
#[derive(Debug, Clone, Copy, Default)]
struct ObjectFifoInfo {
shade: Option<GrayShade>,
palette: ObjectPalette,
struct ObjPixelProperty {
shade_id: u8,
palette_kind: ObjectPaletteKind,
priority: RenderPriority,
}
// FIXME: Fifo Registers have a known size. Are heap allocations
// really necessary here?
#[derive(Debug, Clone)]
struct FifoRenderer {
back: VecDeque<BackgroundFifoInfo>,
obj: VecDeque<ObjectFifoInfo>,
struct PixelFifo {
back: VecDeque<BgPixelProperty>,
obj: VecDeque<ObjPixelProperty>,
enabled: bool,
}
impl FifoRenderer {
impl PixelFifo {
fn is_enabled(&self) -> bool {
self.enabled
}
@ -931,7 +940,7 @@ impl FifoRenderer {
}
}
impl Default for FifoRenderer {
impl Default for PixelFifo {
fn default() -> Self {
Self {
back: VecDeque::with_capacity(8),

20
src/ppu/types.rs
View File

@ -332,7 +332,7 @@ bitfield! {
pub from into RenderPriority, priority, set_priority: 7, 7;
pub y_flip, set_y_flip: 6;
pub x_flip, set_x_flip: 5;
pub from into ObjectPaletteId, palette, set_palette: 4, 4;
pub from into ObjectPaletteKind, palette, set_palette: 4, 4;
}
impl Eq for ObjectFlags {}
@ -368,23 +368,29 @@ impl Default for ObjectFlags {
}
#[derive(Debug, Clone, Copy)]
pub enum ObjectPaletteId {
pub enum ObjectPaletteKind {
Zero = 0,
One = 1,
}
impl From<u8> for ObjectPaletteId {
impl Default for ObjectPaletteKind {
fn default() -> Self {
Self::Zero
}
}
impl From<u8> for ObjectPaletteKind {
fn from(byte: u8) -> Self {
match byte & 0b01 {
0b00 => ObjectPaletteId::Zero,
0b01 => ObjectPaletteId::One,
0b00 => ObjectPaletteKind::Zero,
0b01 => ObjectPaletteKind::One,
_ => unreachable!("{:#04X} is not a valid value for BgPaletteNumber", byte),
}
}
}
impl From<ObjectPaletteId> for u8 {
fn from(palette_num: ObjectPaletteId) -> Self {
impl From<ObjectPaletteKind> for u8 {
fn from(palette_num: ObjectPaletteKind) -> Self {
palette_num as u8
}
}