diff --git a/src/ppu.rs b/src/ppu.rs index c59f247..65789e6 100644 --- a/src/ppu.rs +++ b/src/ppu.rs @@ -13,7 +13,6 @@ pub struct Ppu { frame_buf: [u8; GB_WIDTH * GB_HEIGHT * 4], pub stat: LCDStatus, cycles: Cycles, - mode: Mode, } impl Ppu { @@ -23,38 +22,46 @@ impl Ppu { // let tmp: u32 = self.cycles.into(); // println!("Mode: {:?} | Cycles: {}", self.mode, tmp); - match self.mode { - Mode::OAMScan => { + match self.stat.mode() { + Mode::OamScan => { if self.cycles >= 80.into() { - self.cycles %= 80; - self.mode = Mode::Draw; + self.stat.set_mode(Mode::Drawing); } } - Mode::Draw => { + Mode::Drawing => { + // This mode can take from 172 -> 289 Cycles + // Remember: There's no guarantee that we start this mode + // with self.cycles == 80, since we aren't going for an accurate + // emulator + + // TODO: This 172 needs to be variable somehow? if self.cycles >= 172.into() { - // 172 -> 129 Cycles - // self.cycles %= 172; - self.mode = Mode::HBlank; + self.stat.set_mode(Mode::HBlank); } } Mode::HBlank => { - // The 80 comes from the 80 cycles we made disappear in OAMScan above. - if self.cycles >= (456 - 80).into() { - self.cycles %= 456 - 80; + // We've reached the end of a scanline + if self.cycles >= 456.into() { self.pos.line_y += 1; - if self.pos.line_y >= 144 { - self.mode = Mode::VBlank; - } + let next_mode = if self.pos.line_y >= 143 { + Mode::VBlank + } else { + Mode::OamScan + }; + + self.stat.set_mode(next_mode); } } Mode::VBlank => { + // We've reached the end of the screen + if self.cycles >= 456.into() { self.cycles %= 456; self.pos.line_y += 1; - if self.pos.line_y == 154 { - self.mode = Mode::OAMScan; + if self.pos.line_y >= 153 { + self.stat.set_mode(Mode::OamScan); self.pos.line_y = 0; } } @@ -78,19 +85,9 @@ impl Default for Ppu { oam: vec![0; 160].into_boxed_slice(), cycles: 0.into(), frame_buf: [0; GB_WIDTH * GB_HEIGHT * 4], - mode: Mode::OAMScan, } } } - -#[derive(Debug, Clone, Copy)] -enum Mode { - OAMScan, - Draw, - HBlank, - VBlank, -} - bitfield! { pub struct LCDStatus(u8); impl Debug; @@ -98,8 +95,14 @@ bitfield! { pub oam_intr, set_oam_intr: 5; pub vblank_intr, set_vblank_intr: 4; pub hblank_intr, set_hblank_intr: 3; - pub lyc_ly_flag, _: 2; - pub from into LCDMode, mode, _: 1, 0; + pub coincidence, _: 2; // LYC == LY Flag + from into Mode, _mode, set_mode: 1, 0; +} + +impl LCDStatus { + pub fn mode(&self) -> Mode { + self._mode() + } } impl Copy for LCDStatus {} @@ -128,26 +131,32 @@ impl From for u8 { } #[derive(Debug, Clone, Copy)] -pub enum LCDMode { +pub enum Mode { HBlank = 0, VBlank = 1, - Oam = 2, - Transfer = 3, + OamScan = 2, + Drawing = 3, } -impl From for LCDMode { +impl From for Mode { fn from(byte: u8) -> Self { match byte { 0b00 => Self::HBlank, 0b01 => Self::VBlank, - 0b10 => Self::Oam, - 0b11 => Self::Transfer, + 0b10 => Self::OamScan, + 0b11 => Self::Drawing, _ => unreachable!("{:#04X} is not a valid value for LCDMode", byte), } } } -impl Default for LCDMode { +impl From for u8 { + fn from(mode: Mode) -> Self { + mode as u8 + } +} + +impl Default for Mode { fn default() -> Self { Self::HBlank } @@ -270,7 +279,7 @@ impl Default for ObjSize { } #[derive(Debug, Clone, Copy)] -enum GrayShade { +pub enum GrayShade { White = 0, LightGray = 1, DarkGray = 2,