WIP PPU CGB support

src/bus.rs

@@ -1,6 +1,7 @@
 use std::ops::RangeInclusive;
 use crate::utils::join_bytes;
 use crate::rom::{ROM, load_rom};
+use crate::ram::{RAM, DMGRAM, CGBRAM, WRAM_BANK_SELECT_ADDRESS};
 use crate::ppu::{
     PPU,
     DMA_ADDRESS,
@@ -29,6 +30,7 @@ pub const HIGH_RAM: RangeInclusive<u16>                  = 0xFF80..=0xFFFE;
 pub struct Bus {
     data: [u8; 0x10000],
     pub rom: Box<dyn ROM>,
+    pub ram: Box<dyn RAM>,
     pub ppu: PPU,
     pub joypad: Joypad,
     pub timer: Timer,
@@ -51,10 +53,16 @@ impl Bus {
                 std::process::exit(1);
             },
         };
+        let info = rom.info().clone();
+        let cgb_mode = info.cgb_features() || info.cgb_only();
         let mut bus = Self {
             data: [0x00; 0x10000],
             rom,
-            ppu: PPU::new(),
+            ram: match cgb_mode {
+                true => Box::new(CGBRAM::new()),
+                false => Box::new(DMGRAM::new()),
+            },
+            ppu: PPU::new(cgb_mode),
             joypad: Joypad::new(),
             timer: Timer::new(),
             sound: Sound::new(),
@@ -90,10 +98,14 @@ impl Bus {
     pub fn read(&self, address: u16) -> u8 {
         if BANK_ZERO.contains(&address) || BANK_SWITCHABLE.contains(&address)  || EXTERNAL_RAM.contains(&address) {
             return self.rom.read(address);
+        } else if WORK_RAM_1.contains(&address) || WORK_RAM_2.contains(&address) || address == WRAM_BANK_SELECT_ADDRESS {
+            return self.ram.read(address);
+        } else if ECHO_RAM.contains(&address) {
+            return self.ram.read(WORK_RAM_1.min().unwrap() + ((address - ECHO_RAM.min().unwrap()) & 0x1FFF));
         } else if address == INTERRUPT_ENABLE_ADDRESS || address == INTERRUPT_FLAG_ADDRESS {
             return self.interrupts.read(address);
         } else if VIDEO_RAM.contains(&address) {
-            return self.ppu.read_vram(address);
+            return self.ppu.read_vram_external(address);
         } else if SPRITE_ATTRIBUTE_TABLE.contains(&address) {
             return self.ppu.read_oam(address);
         } else if PPU::is_io_register(address) {
@@ -121,17 +133,12 @@ impl Bus {
             self.rom.write(address, data);
         } else if address == INTERRUPT_ENABLE_ADDRESS || address == INTERRUPT_FLAG_ADDRESS {
             self.interrupts.write(address, data);
-        } else if WORK_RAM_1.contains(&address) || WORK_RAM_2.contains(&address) {
-            self.data[address as usize] = data;
-            // Copy to the ECHO RAM
-            if address <= 0xDDFF {
-                self.data[(ECHO_RAM.min().unwrap() + (address - WORK_RAM_1.min().unwrap())) as usize] = data;
-            }
+        } else if WORK_RAM_1.contains(&address) || WORK_RAM_2.contains(&address) || address == WRAM_BANK_SELECT_ADDRESS {
+            self.ram.write(address, data);
         } else if EXTERNAL_RAM.contains(&address) {
             self.rom.write(address, data);
         } else if ECHO_RAM.contains(&address) {
-            self.data[address as usize] = data;
-            self.data[(WORK_RAM_1.min().unwrap() + (address - ECHO_RAM.min().unwrap())) as usize] = data; // Copy to the working RAM
+            self.ram.write(WORK_RAM_1.min().unwrap() + ((address - ECHO_RAM.min().unwrap()) & 0x1FFF), data);
         } else if Timer::is_io_register(address) {
             self.timer.set_register(address, data);
         } else if Sound::is_io_register(address) {
@@ -140,7 +147,7 @@ impl Bus {
             let byte = self.data[address as usize];
             self.data[address as usize] = (data & 0b11110000) | (byte & 0b00001111);
         } else if VIDEO_RAM.contains(&address) {
-            return self.ppu.write_vram(address, data);
+            return self.ppu.write_vram_external(address, data);
         } else if SPRITE_ATTRIBUTE_TABLE.contains(&address) {
             return self.ppu.write_oam(address, data);
         } else if address == DMA_ADDRESS {

src/lib.rs

@@ -4,6 +4,7 @@ pub mod ppu;
 pub mod timer;
 pub mod sound;
 pub mod rom;
+pub mod ram;
 pub mod bus;
 pub mod interrupts;
 pub mod joypad;

src/ppu.rs

@@ -26,6 +26,7 @@ pub const OBJECT_PALETTE_0_ADDRESS: u16 = 0xFF48;
 pub const OBJECT_PALETTE_1_ADDRESS: u16 = 0xFF49;
 pub const WINDOW_Y_ADDRESS: u16 = 0xFF4A;
 pub const WINDOW_X_ADDRESS: u16 = 0xFF4B;
+pub const VRAM_BANK_SELECT_ADDRESS: u16 = 0xFF4F;
 
 pub const TILE_MAP_ADDRESS: u16 = 0x9800;
 
@@ -126,6 +127,26 @@ pub enum LCDStatus {
     ModeFlag(LCDStatusModeFlag),
 }
 
+struct BgAttributes {
+    bg_to_oam_priority: bool,
+    vertical_flip: bool,
+    horizontal_flip: bool,
+    vram_bank: u8,
+    palette_number: u8,
+}
+
+impl BgAttributes {
+    pub fn new(byte: u8) -> Self {
+        Self {
+            bg_to_oam_priority: get_bit(byte, BitIndex::I7),
+            vertical_flip: get_bit(byte, BitIndex::I6),
+            horizontal_flip: get_bit(byte, BitIndex::I5),
+            vram_bank: get_bit(byte, BitIndex::I3) as u8,
+            palette_number: byte & 0b111,
+        }
+    }
+}
+
 struct Sprite {
     x: u8,
     y: u8,
@@ -136,6 +157,8 @@ struct Sprite {
     y_flip: bool,
     over_bg: bool,
     bit_pixels: Option<[u8; 8]>,
+    vram_bank: u8,
+    palette_number: u8,
 }
 
 impl Sprite {
@@ -229,13 +252,15 @@ pub struct PPU {
     scroll_y: u8,
     window_x: u8,
     window_y: u8,
-    io_registers: [u8; 12],
-    vram: [u8; 0x2000],
+    io_registers: [u8; 16],
+    vram: [u8; 0x2000 * 2],
     oam: [u8; 0xA0],
+    vram_bank: u8,
+    cgb_mode: bool,
 }
 
 impl PPU {
-    pub fn new() -> Self {
+    pub fn new(cgb_mode: bool) -> Self {
         Self {
             state: false,
             background_priority: false,
@@ -256,21 +281,41 @@ impl PPU {
             scroll_y: 0,
             window_x: 0,
             window_y: 0,
-            io_registers: [0; 12],
-            vram: [0; 0x2000],
+            io_registers: [0; 16],
+            vram: [0; 0x2000 * 2],
             oam: [0; 0xA0],
+            vram_bank: 0,
+            cgb_mode,
         }
     }
 
-    pub fn is_io_register(address: u16) -> bool {
-        address >= 0xFF40 && address <= 0xFF4B
+    pub fn set_vram_bank(&mut self, bank: u8) {
+        if self.cgb_mode {
+            self.vram_bank = bank & 1;
+        }
     }
 
-    pub fn read_vram(&self, address: u16) -> u8 {
+    pub fn get_vram_bank(&self) -> u8 {
+        self.vram_bank | 0xFE
+    }
+
+    pub fn is_io_register(address: u16) -> bool {
+        address >= 0xFF40 && address <= 0xFF4F
+    }
+
+    pub fn read_vram_external(&self, address: u16) -> u8 {
+        self.vram[((address + (0x2000 * self.vram_bank as u16)) - 0x8000) as usize]
+    }
+
+    pub fn write_vram_external(&mut self, address: u16, data: u8) {
+        self.vram[((address + (0x2000 * self.vram_bank as u16)) - 0x8000) as usize] = data;
+    }
+
+    fn read_vram(&self, address: u16) -> u8 {
         self.vram[(address - 0x8000) as usize]
     }
 
-    pub fn write_vram(&mut self, address: u16, data: u8) {
+    fn write_vram(&mut self, address: u16, data: u8) {
         self.vram[(address - 0x8000) as usize] = data;
     }
 
@@ -283,7 +328,9 @@ impl PPU {
     }
 
     pub fn get_register(&self, address: u16) -> u8 {
-        if address == LCD_CONTROL_ADDRESS {
+        if address == VRAM_BANK_SELECT_ADDRESS {
+            return self.get_vram_bank();
+        } else if address == LCD_CONTROL_ADDRESS {
             return self.lcd_control;
         } else if address == LCD_Y_ADDRESS {
             return self.lcd_y;
@@ -292,7 +339,9 @@ impl PPU {
     }
 
     pub fn set_register(&mut self, address: u16, data: u8) {
-        if address == LCD_Y_ADDRESS {
+        if address == VRAM_BANK_SELECT_ADDRESS {
+            return self.set_vram_bank(data);
+        } else if address == LCD_Y_ADDRESS {
             return;
         } else if address == LCD_CONTROL_ADDRESS {
             self.lcd_control = data;
@@ -465,11 +514,18 @@ impl PPU {
                 y_flip: get_bit(attributes, BitIndex::I6),
                 over_bg: get_bit(attributes, BitIndex::I7),
                 bit_pixels: None,
+                vram_bank: match self.cgb_mode && get_bit(attributes, BitIndex::I3) {
+                    true => 1,
+                    false => 0,
+                },
+                palette_number: attributes & 0b111,
             });
 
             addr += 4;
         }
-        self.sprite_buffer.sort_by(|a, b| a.x().cmp(&b.x()));
+        if !self.cgb_mode {
+            self.sprite_buffer.sort_by(|a, b| a.x().cmp(&b.x()));
+        }
     }
 
     fn find_sprite_pixel(&mut self) -> Option<(Pixel, bool)> {
@@ -522,12 +578,17 @@ impl PPU {
         self.force_set_register(LCD_STATUS_ADDRESS, byte);
     }
 
-    fn get_tile_bytes(&self, x: u8, y: u8, tilemap_area: u16, default_method: bool) -> (u8, u8) {
+    fn get_tile_bytes(&self, x: u8, y: u8, tilemap_area: u16, default_method: bool) -> (u8, u8, BgAttributes) {
         let index_x = x as u16 / 8;
         let index_y = (y as u16 / 8) * 32;
         let index = index_x + index_y;
-        let tile_line = (y).rem_euclid(8) * 2;
         let tile_number = self.read_vram(tilemap_area + index as u16) as u16;
+        let mut tile_line = (y).rem_euclid(8);
+        let attributes = BgAttributes::new(self.read_vram(tilemap_area + 0x2000 + index as u16));
+        if self.cgb_mode && attributes.vertical_flip {
+            tile_line = 7 - tile_line;
+        }
+        tile_line = tile_line * 2;
         let addr = if default_method {
             0x8000 + tile_line as u16 + (tile_number * 16)
         } else {
@@ -537,7 +598,31 @@ impl PPU {
             (base + tile_line + (tile_number * 16)) as u16
         };
 
-        (self.read_vram(addr), self.read_vram(addr + 1))
+        if !self.cgb_mode {
+            return (self.read_vram(addr), self.read_vram(addr + 1), attributes);
+        }
+        let byte1 = self.read_vram(addr + (0x2000 * (attributes.vram_bank as u16)));
+        let byte2 = self.read_vram(addr + (0x2000 * (attributes.vram_bank as u16)) + 1);
+        if attributes.horizontal_flip {
+            let byte1 = ((byte1 >> 7) & 0b1) |
+                    ((byte1 >> 5) & 0b10) |
+                    ((byte1 >> 3) & 0b100) |
+                    ((byte1 >> 1) & 0b1000) |
+                    ((byte1 << 1) & 0b10000) |
+                    ((byte1 << 3) & 0b100000) |
+                    ((byte1 << 5) & 0b1000000) |
+                    ((byte1 << 7) & 0b10000000);
+            let byte2 = ((byte2 >> 7) & 0b1) |
+                    ((byte2 >> 5) & 0b10) |
+                    ((byte2 >> 3) & 0b100) |
+                    ((byte2 >> 1) & 0b1000) |
+                    ((byte2 << 1) & 0b10000) |
+                    ((byte2 << 3) & 0b100000) |
+                    ((byte2 << 5) & 0b1000000) |
+                    ((byte2 << 7) & 0b10000000);
+            return (byte1, byte2, attributes);
+        }
+        return (byte1, byte2, attributes);
     }
 
     fn get_window_pixel(&mut self) -> Option<Pixel> {
@@ -577,7 +662,7 @@ impl PPU {
                     true  => 0x9C00,
                     false => 0x9800,
                 };
-                let (tile_byte_1, tile_byte_2) = self.get_tile_bytes(x, y, tilemap_area, default_mode);
+                let (tile_byte_1, tile_byte_2, _) = self.get_tile_bytes(x, y, tilemap_area, default_mode);
                 let bit_pixels_array = PPU::get_byte_pixels(tile_byte_1, tile_byte_2);
                 self.current_window_pixels = Some(bit_pixels_array);
 
@@ -614,7 +699,7 @@ impl PPU {
                     true  => 0x9C00,
                     false => 0x9800,
                 };
-                let (tile_byte_1, tile_byte_2) = self.get_tile_bytes(x, y, tilemap_area, default_mode);
+                let (tile_byte_1, tile_byte_2, _) = self.get_tile_bytes(x, y, tilemap_area, default_mode);
                 let bit_pixels_array = PPU::get_byte_pixels(tile_byte_1, tile_byte_2);
                 self.current_background_pixels = Some(bit_pixels_array);
 

src/ram.rs

@@ -0,0 +1,80 @@
+pub const WRAM_BANK_SELECT_ADDRESS: u16 = 0xFF70;
+
+pub trait RAM {
+    fn read(&self, address: u16) -> u8;
+    fn write(&mut self, address: u16, value: u8);
+}
+
+pub struct DMGRAM {
+    data: [u8; 4096 * 2],
+}
+
+impl DMGRAM {
+    pub fn new() -> Self {
+        Self {
+            data: [0; 4096 * 2],
+        }
+    }
+}
+
+impl RAM for DMGRAM {
+    fn read(&self, address: u16) -> u8 {
+        if address == WRAM_BANK_SELECT_ADDRESS {
+            return 0xFF;
+        }
+        self.data[(address - 0xC000) as usize]
+    }
+
+    fn write(&mut self, address: u16, value: u8) {
+        if address == WRAM_BANK_SELECT_ADDRESS {
+            return;
+        }
+        self.data[(address - 0xC000) as usize] = value;
+    }
+}
+
+
+pub struct CGBRAM {
+    data: [u8; 4096 * 8],
+    bank: u8,
+
+}
+
+impl CGBRAM {
+    pub fn new() -> Self {
+        Self {
+            data: [0; 4096 * 8],
+            bank: 1,
+        }
+    }
+
+    fn switch_bank(&mut self, bank: u8) {
+        self.bank = bank;
+        if self.bank > 7 {
+            self.bank = 7;
+        } else if bank == 0 {
+            self.bank = 0;
+        }
+    }
+}
+
+impl RAM for CGBRAM {
+    fn read(&self, address: u16) -> u8 {
+        if address == WRAM_BANK_SELECT_ADDRESS {
+            return self.bank;
+        }
+        if address <= 0xCFFF {
+            return self.data[(address - 0xC000) as usize];
+        }
+        self.data[((address - 0xC000) as usize) * (self.bank as usize)]
+    }
+
+    fn write(&mut self, address: u16, value: u8) {
+        if address == WRAM_BANK_SELECT_ADDRESS {
+            return self.switch_bank(value);
+        } else if address <= 0xCFFF {
+            return self.data[(address - 0xC000) as usize] = value;
+        }
+        self.data[((address - 0xC000) as usize) * (self.bank as usize)] = value;
+    }
+}

src/rom.rs

@@ -41,6 +41,7 @@ pub fn load_rom(_filename: &str) -> std::io::Result<Box<dyn ROM>> {
         filename: "".to_string(),
         publisher: "".to_string(),
         title: "".to_string(),
+        cgb_features: false,
         cgb_only: false,
         sgb_features: false,
         has_ram: false,
@@ -150,6 +151,7 @@ pub struct ROMInfo {
     filename: String,
     publisher: String,
     title: String,
+    cgb_features: bool,
     cgb_only: bool,
     sgb_features: bool,
     has_ram: bool,
@@ -161,6 +163,14 @@ pub struct ROMInfo {
 }
 
 impl ROMInfo {
+    pub fn cgb_features(&self) -> bool {
+        self.cgb_features
+    }
+
+    pub fn cgb_only(&self) -> bool {
+        self.cgb_only
+    }
+
     pub fn set_filename(&mut self, filename: String) {
         self.filename = filename;
     }
@@ -205,6 +215,7 @@ impl ROMInfo {
             },
             publisher: "".to_string(), // TODO: Extract publisher
             title: "".to_string(), // TODO: Extract the game title
+            cgb_features: bytes[CGB_FLAG_ADDRESS as usize] == 0x80,
             cgb_only: bytes[CGB_FLAG_ADDRESS as usize] == 0xC0,
             sgb_features: bytes[SGB_FLAG_ADDRESS as usize] == 0x03,
             has_ram: match rom_type {

src/sound.rs

@@ -1,7 +1,7 @@
 use std::env;
 use std::ops::RangeInclusive;
 use std::sync::{Arc, Mutex};
-use cpal::{Stream, StreamConfig, Device, Sample};
+use cpal::{Stream, StreamConfig, Device, Sample, SampleRate};
 use cpal::traits::{DeviceTrait, HostTrait, StreamTrait};
 use crate::cpu::Cycles;
 use crate::utils::join_bytes;
@@ -34,6 +34,8 @@ pub const NR52_ADDRESS: u16 = 0xFF26;
 
 pub const WAVE_PATTERN_RAM: RangeInclusive<u16> = 0xFF30..=0xFF3F;
 
+pub const SAMPLE_RATE: u32 = 48000;
+
 const WAVE_DUTY_PATTERNS: [[u8; 8]; 4] = [
     [0, 0, 0, 0, 0, 0, 0, 1],
     [0, 0, 0, 0, 0, 0, 1, 1],
@@ -48,25 +50,15 @@ struct ChannelTwo {
     frequency_timer: u16,
     duty_position: usize,
     sample_timer: usize,
-    sample_rate: usize,
     buffer_pos: usize,
 }
 
 impl ChannelTwo {
-    pub fn new(device: &Device, config: &StreamConfig, sample_rate: usize) -> Self {
+    pub fn new(device: &Device, config: &StreamConfig) -> Self {
         let mut count: usize = 0;
-        // let mut count: f32 = 0.0;
-        let buffer = Arc::new(Mutex::new(vec![0.0; sample_rate]));
+        let buffer = Arc::new(Mutex::new(vec![0.0; SAMPLE_RATE as usize]));
         let buffer_clone = buffer.clone();
         let stream = device.build_output_stream(&config, move |data: &mut [f32], _| {
-            /* for sample in data.iter_mut() {
-                let y: f32 = ((count / (sample_rate as f32)) * 440.0 * 2.0 * 3.14159).sin().clamp(-1.0, 1.0);
-                *sample = Sample::from(&y);
-                count += 1.0;
-                if count >= sample_rate as f32 {
-                    count = 0.0;
-                }
-            } */
             let b = buffer_clone.lock().unwrap();
             for sample in data.iter_mut() {
                 *sample = Sample::from(&b[count]);
@@ -84,7 +76,6 @@ impl ChannelTwo {
             duty_position: 0,
             sample_timer: 0,
             buffer_pos: 0,
-            sample_rate,
             buffer,
         }
     }
@@ -114,10 +105,10 @@ impl ChannelTwo {
                 self.duty_position = 0;
             }
         }
-        self.sample_timer = self.sample_timer.saturating_add(self.sample_rate);
+        self.sample_timer = self.sample_timer.saturating_add(SAMPLE_RATE as usize);
         if self.sample_timer >= 4194304 {
             self.update_buffer(duty);
-            self.sample_timer = 0;
+            self.sample_timer -= 4194304;
         }
     }
 }
@@ -148,13 +139,12 @@ impl Sound {
                 .expect("error while querying configs");
             let supported_config = supported_configs_range.next()
                 .expect("no supported config?!")
-                .with_max_sample_rate();
+                .with_sample_rate(SampleRate(SAMPLE_RATE));
             // let err_fn = |err| eprintln!("an error occurred on the output audio stream: {}", err);
-            let sample_rate = supported_config.sample_rate().0;
             let config: StreamConfig = supported_config.into();
             return Self {
                 io_registers: [0; 48],
-                channel_two: Some(ChannelTwo::new(&device, &config, sample_rate as usize)),
+                channel_two: Some(ChannelTwo::new(&device, &config)),
             };
         }