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chore(ppu): refactor small part of bg fetcher

This commit is contained in:
Rekai Nyangadzayi Musuka 2021-05-08 15:52:09 -05:00
parent fd2b64496c
commit e89e89df5b
1 changed files with 30 additions and 32 deletions
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60
src/ppu.rs
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@ -299,11 +299,12 @@ impl Ppu {
match self.fetch.back.state {
TileNumber => {
let x_pos = self.fetch.x_pos;
let window = self.window_stat.should_draw();
let addr = self
.fetch
.bg_tile_num_addr(&self.control, &self.pos, x_pos, window);
self.fetch
.back
.should_render_window(self.window_stat.should_draw());
let addr = self.fetch.bg_tile_num_addr(&self.control, &self.pos, x_pos);
let id = self.read_byte(addr);
self.fetch.back.tile.with_id(id);
@ -313,11 +314,7 @@ impl Ppu {
}
ToLowByteSleep => self.fetch.back.next(TileLowByte),
TileLowByte => {
let window = self.window_stat.should_draw();
let addr = self
.fetch
.bg_byte_low_addr(&self.control, &self.pos, window);
let addr = self.fetch.bg_byte_low_addr(&self.control, &self.pos);
let low = self.read_byte(addr);
self.fetch.back.tile.with_low_byte(low);
@ -326,11 +323,7 @@ impl Ppu {
}
ToHighByteSleep => self.fetch.back.next(TileHighByte),
TileHighByte => {
let window = self.window_stat.should_draw();
let addr = self
.fetch
.bg_byte_low_addr(&self.control, &self.pos, window);
let addr = self.fetch.bg_byte_low_addr(&self.control, &self.pos);
let high = self.read_byte(addr + 1);
self.fetch.back.tile.with_high_byte(high);
@ -411,11 +404,13 @@ impl Ppu {
self.fifo.back.clear();
}
} else {
if self.window_stat.should_draw() {
self.window_stat.set_should_draw(false);
}
}
}
}
}
fn reset(&mut self) {
// FIXME: Discover what actually is supposed to be reset here
@ -652,19 +647,14 @@ impl PixelFetcher {
self.back.vblank_reset();
}
fn bg_tile_num_addr(
&self,
control: &LCDControl,
pos: &ScreenPosition,
x_pos: u8,
window: bool,
) -> u16 {
fn bg_tile_num_addr(&self, control: &LCDControl, pos: &ScreenPosition, x_pos: u8) -> u16 {
let line_y = pos.line_y;
let scroll_y = pos.scroll_y;
let scroll_x = pos.scroll_x;
let is_window = self.back.is_window_tile();
// Determine which tile map is being used
let tile_map = if window {
let tile_map = if is_window {
control.win_tile_map_addr()
} else {
control.bg_tile_map_addr()
@ -675,8 +665,8 @@ impl PixelFetcher {
// Offsets are ANDed wih 0x3FF so that we stay in bounds of tile map memory
// TODO: Is this necessary / important in other fetcher modes?
let scx_offset = if window { 0u16 } else { scroll_x as u16 / 8 } & 0x1F;
let y_offset = if window {
let scx_offset = if is_window { 0u16 } else { scroll_x as u16 / 8 } & 0x1F;
let y_offset = if is_window {
self.back.window_line.count() as u16 / 8
} else {
((line_y as u16 + scroll_y as u16) & 0xFF) / 8
@ -687,14 +677,10 @@ impl PixelFetcher {
tile_map_addr + ((x_offset + y_offset) & 0x3FF)
}
fn bg_byte_low_addr(
&mut self,
control: &LCDControl,
pos: &ScreenPosition,
window: bool,
) -> u16 {
fn bg_byte_low_addr(&mut self, control: &LCDControl, pos: &ScreenPosition) -> u16 {
let line_y = pos.line_y;
let scroll_y = pos.scroll_y;
let is_window = self.back.is_window_tile();
let id = self.back.tile.id.expect("Tile Number unexpectedly missing");
@ -703,7 +689,7 @@ impl PixelFetcher {
TileDataAddress::X8000 => 0x8000 + (id as u16).wrapping_mul(16),
};
let offset = if window {
let offset = if is_window {
self.back.window_line.count() % 8
} else {
(line_y + scroll_y) % 8
@ -757,10 +743,19 @@ struct BackgroundFetcher {
state: FetcherState,
tile: TileBuilder,
window_line: WindowLineCounter,
is_window_title: bool,
enabled: bool,
}
impl BackgroundFetcher {
fn should_render_window(&mut self, value: bool) {
self.is_window_title = value;
}
fn is_window_tile(&self) -> bool {
self.is_window_title
}
fn pause(&mut self) {
self.enabled = false;
}
@ -790,6 +785,8 @@ impl Fetcher for BackgroundFetcher {
fn hblank_reset(&mut self) {
self.reset();
self.is_window_title = false;
self.window_line.hblank_reset();
self.enabled = true;
@ -801,6 +798,7 @@ impl Default for BackgroundFetcher {
Self {
state: Default::default(),
tile: Default::default(),
is_window_title: Default::default(),
window_line: Default::default(),
enabled: true,
}